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Title: Florida Tomato Institute proceedings
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Permanent Link: http://ufdc.ufl.edu/UF00089451/00008
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Title: Florida Tomato Institute proceedings
Physical Description: Serial
Language: English
Creator: Gulf Coast Research and Education Center. Institute of Food and Agricultural Sciences.
Publisher: Gulf Coast Research and Education Center. Institute of Food and Agricultural Sciences.
Place of Publication: Wimauma, Fla.
Publication Date: 2009
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Volume ID: VID00008
Source Institution: University of Florida
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Table of Contents
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The Ritz-Carlton, Naples, Florida I September 9,20091 PRO 526

9:00 Welcome Millie Ferrer, UF/IFAS Interim Extension Dean and Director, Gainesville
9:05 State of the Industry Reggie Brown, Florida Tomato Committee, Maitland
9:20 Heating the water used in dump tanks, flumes and washers: Where did this originate? Jerry Bartz, UF/IFAS Plant
Pathology Dept., Gainesville page 6
9:40 Assessment of microbes in tomato packinghouses Fred Bonilla, UF Dept. of Infectious Diseases and Pathology,
Gainesville page 8
10:00 Can we use CRF in tomato production? Monica Ozores-Hampton, UF/IFAS SWFREC, Immokalee page 10
10:15 Sulfur fertilization in tomato production Bielinski Santos, UF/IFAS GCREC, Wimauma page 14
10:30 The effect of TYLCV on tomato yield depends upon age of the plant at time of inoculation M. Lapidot, UF/IFAS Plant
Pathology Dept., Gainesville page 16
10:45 Progress in making TYLCV and bacterial spot resistance breeding more efficient and the latest variety outlook -
Jay Scott, UF/IFAS GCREC, Wimauma page 20
11:05 Breeding for disease resistance in fresh market tomatoes JeremyEdwards, UF/IFAS GCREC, Wimauma
11:25 Lunch (on your own)

1:00 CUE and fumigant assessment update Dan Botts, Florida Fruits and Vegetables Association, Maitland
1:20 Fumigation for tomato today: Methyl bromide alternatives, the future of drip fumigation and outcomes and
impacts of EPA reassessments of soil fumigants Joe Noling, UF/IFAS CREC, Lake Alfred page 22
1:40 Ralstonia solanacearum Race 3 biovar 2 causing bacterial wilt of tomato: Strategies for best management of a
Select Agent pathogen Patrice Champoiseau, UF/IFAS Plant Pathology Dept., Gainesville page 25
2:00 The economic impact of Bacterial Spot on the tomato industry John Vansickle, UF/IFAS Food & Resource
Economics Dept., Gainesville page 30
2:20 Identification of weed reservoirs of tomato yellow leaf curl virus in florida Jane Polston, UF/IFAS Plant Pathology
Dept., Gainesville page 32
2:40 Industry updates Crystal Snodgrass, Manatee County Extension, Palmetto
3:30 Adjourn

Tomato varieties for Florida Steve Olson, UF/IFAS NFREC, Quincy, and Gene McAvoy, UF/IFAS Hendry County Extension, LaBelle
page 34
Water management for tomato Eric Simonne, UF/IFAS Horticultural Sciences Dept., Gainesville page 37
Fertilizer and nutrient management for tomato Eric Simonne, UF/IFAS Horticultural Sciences Dept., Gainesville page 41
Weed control in tomato William Stall, UF/IFAS Horticultural Sciences Dept., Gainesville page 45
Tomato fungicides and other disease management products Garry Vallad, UF/IFAS GCREC, Wimauma page 47
Selected insecticides approved for use on insects that attack tomatoes Susan Webb, Entomology and Nematology
Dept., Gainesville page 49
Nematicides registered for use on Florida tomatoes Joe Noling, UF/IFAS CREC, Lake Alfredpage 52





J. A. Bartz' and S. A. Sargent2
SUniversity of Florida/IFAS, Plant Pathology Dept., Gainesville, FL, softbart@ufl.edu
2 University of Florida/IFAS, Dept. of Horticultural Sciences, Gainesville, FL

In July, 1978 a 30-lb box of packed toma-
toes (variety'lmproved Walter') was sent
from a receiver in Orlando to the posthar-
vest Pathology Laboratory in Gainesville
(Bartz, 1980). The fruit had been grown
and packed in the Quincy region. Since
the area was new to tomato production
back then, ripening rooms had not yet
been constructed. So,this box had not
been gassed.The shipment had been
rejected by the receiver in Orlando due to
progressive decay.When opened a day lat-
er,60% of the fruit in the box had primary
decay lesions.The survivors were stored
at 68F for 1 weekend an additional 5%
of the original contents had developed
lesions. At this point, the survivors were
more or less fully red and were discarded.
An investigation of the shipment revealed:
59% of the lesions observed were
directly beneath or beside the stem scar and
10% of the lesions were adjacent to or
beneath the blossom scar and internal.
29% of the lesions were midway
between the blossom and stem scar and
2% of the lesions were directly connect-
ed with a wound on the fruit surface.
*> 6 different pathogens were isolated
from lesions.
Fruit in the field were not affected.
*Tank capacity was limited in this new
packing shed operation.
Ambient air temperatures were high.
Calcium hypochlorite was periodically
added to the water system but free chlorine
concentration was not measured.
Symptoms could be reproduced if a
suspension of one of the pathogens was
vacuum-infiltrated into fruit.
The pathogens were isolated, identified
and proven to be the causal agents with
Koch's postulates. Each one was strictly a
wound invader; none could penetrate di-
rectly through the tomato cuticle. Since only
2% of the lesions were clearly associated

with wounds,the pathogens had to have
entered the fruit,which is called internaliza-
tion.An infiltration of fruit by dump tank or
washer water was implicated since fruit that
were vacuum infiltrated with water suspen-
sions of bacteria developed symptoms like
those in the outbreak box.
The question then became: how this
could have happened?Tomato fruits are
filled with air-spaces.Mature-green toma-
toes float when dumped into water.They do
not normally absorb water and certainly do
not absorb any through their waxy surfaces.
Gas exchange between the air outside a fruit
and that inside of it is mostly through the
stem scar (Brooks, 1937),which is precisely
where a majority of the lesions began. But
the stem scar surface is normally dry and
does not act like a sponge; on the contrary,
water added to a dry stem scar beads and
does not penetrate. However,according to
the laws of physics, if a fruit is covered with
water and sufficient pressure is exerted on
the water,some will be forced into openings
on the fruit surface. This situation could
occur if the fruit is submerged deeply in a
dump tank,is struck by a pressurized stream
of water or if it cools while submerged.

Aqueous suspensions of microorganisms
have long been used in plant pathology
laboratories and field plots to inoculate
plants with plant pathogens. The water
provides a vehicle that carries the sus-
pended microbe into wounds, stomata or
other openings in the plant surface. Once
in contact with plant cells,the pathogen
begins its attack. As noted above,vacuum
infiltration of tomato fruit with bacteria
isolated from internal lesions in fruit from
a rejected shipment led to a reproduction
of the symptoms (Bartz, 1980).
The concept of internalizing inocula in this
manner was borrowed from Hall et al. (1970)
who evaluated tomato lines for susceptibil-
ity to graywall by vacuum infiltrating the

fruit with aqueous suspensions of bacteria.
However, one of the first reports where
wash water was reported to carry spoilage
bacteria into an agricultural commodity did
not involve tomato fruit, but rather hen's
eggs (Haines and Moran, 1940). The authors
carefully analyzed the egg shell,determined
that it had pores connecting the shell surface
with internal membranes surrounding the
white and yolk. They reasoned that if the
egg cooled while submerged,vacuums
would develop in the air bubble within the
membrane and airspaces within the shell,
which could suckspoilage bacteria into the
egg. Indeed,warm eggs soaked for 1 hour in
cool water containing a spoilage bacterium,
internalized the inocula and spoiled during
subsequent storage. Similar soaks in water at
the same temperature or greater than that of
the egg led to much lower rates of spoilage.
The first report of tomatoes being soaked
in water came from California and involved
the use of warm water in dump tanks during
colder harvest seasons (Kasmire, 1971).The
fruit surfaces were warmed,which reduced
pitting and scuffing during packing opera-
tions. A 1-minute immersion in warm water
(85 to 90oF) led to the least surface damage,
whereas a 30-second dip into hot water
(135oF) exacerbated the damage. He further
noted that tomatoes at 85oF immersed
for 10 minutes in water at 50oF increased
in weight by 0.17%,whereas a similar im-
mersion in water at 85oF did not result in a
weight increase due to water uptake.
Studer and Kader (1977) investigated the
possibility of using water in 10-ton gondolas
or bulk bins to cushion tomatoes that were
mechanically harvested for fresh market.
They found a high degree of splitting (due
to water uptake) in fruit that were immersed
for 2 hours soon after harvest. The splitting
was increased if the water was cooler than
the fruit at the time of submersion. Even
fruits submerged for 15 minutes were sub-
ject to splitting. However, if the fruits were
stored overnight before being dumped into
the water,splitting was not observed.


The initial research related to water up-
take accompanied by an internalization of
suspended bacteria by freshly harvested
tomato fruits focused on temperature
differences between tomato and water
(Bartz and Showalter,1981). Because
decay problems were reported more
frequently when air temperatures were
high, it was reasoned that fruits may have
cooled after being dumped into unheated
water. The research concentrated on
proving that bacteria and fungi could
be forced into tomato fruits if the fruits
cooled while submerged in suspensions
of decay pathogens. Immersion periods
ranged from 10 to 30 minutes.Weight
increases ranged from 0 to 3.6% and were
generally proportional to the temperature
difference between fruits and water as
well as the contact duration. Fruits initially
at the same temperature as the water did
not increase in weight and rarely devel-
oped decay during subsequent storage.
By contrast, when mature green fruits at
104F were submerged into an aqueous
suspension of soft rot bacteria at 68oF
for 10 minutes,a decay incidence rate of
100% was observed within 2 days of stor-
age.Water uptake increased when certain
surfactants were added to the water
(Bartz, 1982). Depth of submersion, period
of submersion and fruit temperature
were also implicated in increasing water
uptake and subsequent decay develop-
ment. Unusually warm fruits were prone to
absorb water when the water was at the
same temperature or even cooler than the
fruit temperature.These observations led
to the recommendation that the water in
dump tanks and flumes be warmed 1 OF
higher than the highest incoming pulp
temperature and that harvested fruits be
kept out of direct sunlight,which could
increase pulp temperatures (Sherman et
al., 1981). Packinghouse managers were
admonished to measure the pulp tem-
perature of each incoming lot of fruit and
not to make assumptions.
Bartz (1981) noted that a 2-minute
immersion of fruit at 98oF in an aqueous
suspension of soft rot bacteria at the same
temperature did not lead to a weight
increase,although 5% of the fruit developed
bacterial soft rot during a subsequent 8-day
period of storage. If the water was 17F
cooler than the pulp temperature, 15% of
the fruit developed soft rot after a 2-minute
exposure and 98% after a 10-minute expo-
sure. Ogawa etal. (1980) reported prelimi-

nary tests where tomatoes contaminated
with spores of Botrytiscinerea (causal agent
of gray mold) were dipped into water at
100 F orat 65F for 3 minutes. More decay
developed among the fruits that had been
treated with the cool as compared with
warm water. Thus,a 3-minute immersion of
a warm tomato in cool water may be long
enough to establish infiltration. The increase
in decay incidence caused by a fungal
pathogen also implied that fungal spores
could be carried into the fruits along with
water. Vigneaultetal.(2000) observed a
100% incidence of Rhizopus rot among fruits
hydrocooled in water containing spores of
Rhizopus stoloniferand then stored for 10
days at 68oF. By contrast, if the hydrocooler
water also contained 50 ppm free chlorine
at pH 7.0,no decay developed. Thus, main-
tenance of a rapidly acting sanitizer in the
water also affects the decay risk associated
with immersing tomatoes in water.

In a visit to several packinghouses,
Mahovic (2007) noted that the residence
times for fruits in dump tanks ranged
from 30 to 120 seconds.Whether water
uptake and subsequent decay risk driven
by a temperature difference could occur
during a 30- to 120-second exposure,
is unclear. However,what is becoming
increasingly clear is that water uptake
by fruit caused by physical phenomena
should not be allowed due to food safety
concerns. Zhuang etal. (1995) noted that
Salmonella could be internalized into stem
scar tissues like soft rot bacteria. Once
inside the fruits,this human pathogen
could not be successfully eliminated with
current sanitation methods. By contrast,
soft rot bacteria must be in living tissues
in order to cause decay; cells that merely
contaminate upper levels of a dry stem
scar are not able to infect the entire fruit.
But, cells of Salmonella in upper levels of
the stem scar are protected from expo-
sure to sanitizers and may survive for
several days.Thus, methods that protect
fruits from postharvest pathogens may
be only partially successful in a sanitation
program for Salmonella. Before the water
temperature requirement can be modi-
fied, evidence must be developed that a
combination of an approved sanitizer and
a short immersion period will preclude
internalization of Salmonella. *

Bartz, J.A. 1981.Ingress of suspensions ofErwinia
carotovora subsp. carotovora into tomato fruit.

Pages 452-460 in: Proc. Int. Conf. Plant Pathog. Bact.
5th.J. C. Lozano, ed. Centro Internacional deAgricul-
tra Tropical, Call. Colombia. 640 pp.

Bartz,J.A. 1982. Infiltration of tomatoes immersed at
different temperatures to different depths in suspen-
sions ofErwinia carotovora subsp. carotovora. Plant
Dis. 66:302-306.

Bartz,J.A., Mahovic, M., Hermle, C.M., Concelmo, D.
2003. Internalization ofmicroorganisms into tomato
fruit through water congested tissues, Abstracts, 8th
International Congress of Plant Pathology,2003,

Bartz,J.A.,andShowalter,R.K. 1981. Infiltration of
tomatoes by bacteria in aqueous suspension. Phyto-

Brooks, C. 1937. Some effects of waxing tomatoes.
Proc. Am. Soc. Hort. Sci. 35:720.

Haines,R.B.,and Moran,T. 1940. Porosity of and
bacterial invasion through, the shell of the hen's egg.
J.Hyg. 40:453-461.

Hall, C. B., Stall, R. E, and Strobel, J. W. 1970. Dif-
ferential graywall development in tomato stocks
infiltrated with bacteria. Proc. Fla. State Hort. Soc.

Kasmire, R. F 1971. Hot water treatments for toma-
toes. Fruit and Veg. Perishables Handling 29:3-4.
Univ. Cal., California Agric. Ext. Serv., Davis.

Mahovic, M. J. 2007. Use of chlorine, chlorine
compounds and alternatives to chlorination in the
sanitation of tomato water flume dump tanks. Ph.D.
dissertation, University of Florida.

Ogawa,J. M., Hoy, M. W, Manji, B. T., and Hall, D. H.
1980. Proper use of chlorine for postharvest decay
control of fresh market tomatoes. Calif Tomatorama
Inf. Bull. No. 27, Fresh Market Tomato Advis. Board,
Bakersfield, CA.

Sherman, M., Showalter, R. K., Bartz,J.A., and Simone,
G.W. 1981. Tomato packinghouse dump tank sanita-
tion. Veg. Crops Fact Sheet VC-31, Fla Coop. Ext. Serv.
Univ. Fla., Inst. FoodAgric. Sci., Gainesville.

Studer,H.E.and Kader,A.A. 1976-1977. Handling
tomatoes in water. Ann. Rep. Fresh Market Tomato
Res. Prog. Fresh Market Tomato Advisory Board,
Bakersfield, CA 93303. p. 84.

Vigneault, C., Bartz, J. A., and Sargent, S. A. 2000.
Postharvest decay risk associated with hydrocooling
tomatoes. PlantDis.84:1314-1318.

Zhuang, R. Y, Beuchat, L. R., andAngulo, FJ. 1995.
Fate of Salmonella montevideo on and in raw toma-
toes as affected by temperature and treatment with
chlorine. Apple. Environ. Microbiol. 61:2127-2131.





J. Alfredo Bonilla' and Gurpal Toor2
SUniversity of Florida, Dept. of Infectious Diseases and Pathology, Gainesville, FL, bonillaja@vetmed.ufl.edu
2 University of Florida/IFAS, GCREC, Wimauma, FL

The United States enjoys one of the safest
food supplies in the world. Nevertheless,
infectious diseases spread through food
and beverages are a common, distressing
and sometimes life-threatening problem
for millions of people in the United States.
The Center for Disease Control and Pre-
vention estimates that 76 million people
suffer from foodborne illnesses in the
United States each year,which accounts
for 325,000 hospitalizations and more
than 5,000 deaths. The economical toll
from foodborne disease is heavy as health
experts estimate a yearly cost of 5 to 6
billion dollars in direct medical expenses
and lost productivity (CDC, 2009).To this
end,food safety programs are important
to address important health issues related
to food sources, production and consump-
The agriculture community has impor-
tant economic reasons to be concerned
and informed about food safety require-
ments and issues (Lynch et al., 2009).To be
accepted in the marketplace, agricultural
products must meet governmental food
safety standards,and maintain a safety
level that inspires continued consumer
confidence.There are more than 250
known foodborne diseases caused by bac-
teria,viruses or protozoa.Some diseases
are caused by toxins from the disease-
causing microbe, others by the human
body's reaction to the microbial infection.
The sources of food contamination are al-
most as numerous and varied as the con-
taminants themselves. Bacteria,and other
infectious organisms,are pervasive in
the environment and foods may become
contaminated at many stages of food
production,including in the home. Of the
numerous human pathogens transmitted
through contaminated food,Salmonella
spp. and Escherichia coli bacteria represent
two of the most common (and often seri-
ous) foodborne infections in the US with
approximately 40,000 and 73,000 cases
of infection reported annually to the CDC

TABLE 1. Summary of analytical techniques used.
Technique Target
mHPC agar Heterotrophic plate count
mTEC agar E. coli
Tetrathionate Broth Salmonella-enrichment prior to PCR
Rappaport-Vassiliadis R10 Broth Salmonella-enrichment prior to PCR
PCR Salmonella spp. hilA and sdiA genes
PCR E. coli 0157:H7 rfbE gene
PCR Universal 16s rRNA gene

(Frenzen etal.,2005,Chang et al.,2009).
The goal of the study was to assess
the microbial concentration in the wash
tanks at two South Florida tomato pack-
inghouses and assay the packinghouse
water samples for specific pathogens
important to the industry using advance
molecular biology techniques. Our first
objective was to assay the water using
traditional membrane filtration methods
and determine the level of total heterotro-
phic bacteria and E.coli in the wash tanks
over a period of 4 to 6 hours of heavy
operation. Secondly, we assayed the water
and grab samples of tomatoes (before
and after packaging) for Salmonella spp.
and E.coli 0157:H7 using the polymerase
chain reaction (PCR) method,a highly
sensitive DNA amplification technique for
specifically identifying the presence of a

Ninety one water samples were collected
over 4 sampling events and analyzed
for total heterotrophic bacteria and
E.coli using standard membrane filtra-
tion methods as described in"Standard
Methods for the Examination of Water and
Wastewater"(APHA,2005;Table 1) and U.S.
Environmental Protection Agency publica-
tions (2000). Briefly,water samples were
collected from wash tanks every 30 min.
and filtered through 47-mm filters with a
0.45-pm pore size to entrap the bacteria.
The filters were placed onto mHPCagar
for the enumeration of total heterotrophic

bacteria (THB) and on mTEC agar for the
enumeration of thermotolerantE.coli. The
agar plates were analyzed at 24 and 48 hrs.
of incubation and the number of colony-
forming units (CFU)/100 ml was deter-
mined. The concentration of chloride was
also determined for every water sample
For the genetic analysis of the water,
25 ml from 32 of the water samples were
filtered through a 250 mm filter with a 0.45
pm pore size,the bacterial population on
the filter was lysed in a SDS/ProK/CTAB
lysis solution,and the DNA was extracted
and purified. Two PCR primer sets for Sal-
monella spp. (targeting the sdiA and hilA
genes), one primer set for E.coli 0157:H7
(targeting the rfbE gene),and one primer
set for'universal'bacteria (16s rRNA gene)
were used as previously described (Guo
et al., 2000; Halatsi et al., 2006; Omiccioli et
al., 2009).
In an attempt to increase the sensitiv-
ity of the PCR detection of Salmonella, 8
of the water samples processed for DNA
analysis as described above were also
subjected to an enrichment procedure.
Bacteria-containing filters were placed
into culture-grade tubes with Rappaport-
Vassiliadis R10 broth and Tetrathionate
broth and incubated overnight at 37oC.
The broth sample was centrifuged at
10,000 x g for 10 min.,the pellet was lysed
in a SDS/ProK/CTAB lysis solution,and the
DNA was extracted and purified.
Grab samples of tomatoes (approxi-
mately 500 g) were collected from the


truck bins prior to dumping (pre-pro-
cessed) and from the final 25-pound
packing boxes (post-processed). A total of
10 tomato samples were analyzed directly
by PCR and by PCR after the enrichment
procedure.The tomatoes were collected
in a sterile bag and 100 ml of phosphate-
buffered saline (PBS) was added. The bag
was shaken and agitated every 5 min.for
30 min.to remove and collect bacteria off
the surface of the tomatoes. The PBS wash
of the pre-processed and post-processed
tomatoes was also analyzed forTHB by
membrane filtration.

Analysis of total heterotrophic bacteria
(THB) and E. coli bacteria. The concen-
trations ofTHB and E. coli enumerated by
the membrane filtration method were
very low in all wash tank samples analyzed
(Fig. 1). ForTHB, less than 10 CFU per 100
ml of wash tank water was detected in
nearly all samples throughout the 5-6
hrs. of tomato processing. While some
samples were positive for presumptive
coliform bacteria, upon confirmation
tests, E.coliwas not detected in any of the
water samples. An initial concern was the
travel time from collection of the sample,
to transport and analysis in the labora-
tory. The samples were analyzed within 8
hrs. of collection. However,to investigate
whether the extended contact time was
affecting the microbial concentration in
the water samples,we decided to process
the water sample for membrane filtration
onto the agar plates at the packinghouses
and immediately after collection. The
results were comparable,with very few
THB CFU/100ml and no E.coli CFU/100ml
detected in the water. Fig. 1 shows the
average CFU/1 00ml of total heterotro-
phic bacteria and the average chloride
levels detected at the 2 packinghouses.
Importantly,the lower chloride levels used
at packinghouse B did not result in an
increase in bacterial levels.
The pre-processed and post-processed
tomato grab samples had detectable lev-
els ofTHB. TheTHB in the pre-processed
tomatoes ranged from 6.1 x 104 to 3.4 x
101 CFU/100ml of the PBS wash used on
-500 g of tomatoes. The post-processed
samples had, on average,an 81% reduc-
tion (range 73% to 93%) in THB concen-
tration. The EPA"acceptable" level for
total heterotrophic bacteria per 100 ml of
drinking water is 5.0 x 104 CFU. Therefore,
the concentrations detected in this study

FIGURE 1.Total heterotrophic bacteria (CFU/100ml) and chloride levels (mg/L) in wash tank
samples collected over 6 hrs at 2 South Florida packinghouses. Each packinghouse was sampled
at least twice and the averages are reported.
35 1000
Packinghouse A
3**. Packinghouse B 800
30 -

20 0

.1. .. .. .v.v 200 |
0 _
0 1 2 3 4 5 6 7 >
10 Hour



0 1 2 3 4 5 6 7

FIGURE 2. Representative samples of 16s rRNA gene fragments isolated from DNA samples. Lane
M, DNA marker. Lanes 1-2, tomato wash samples. Lanes 3-5, sash tank samples. Lane 6, negative

were relatively low,and the presence of
THB did not correlate with the presence of
human pathogens in the absence of other
indicators of fecal contamination. To this
end,there was no E.coli detected in the
final tomato samples by membrane filtra-
tion or PCR (E coil 0157:H7).
PCR analysis of Salmonella spp. and E.
coli0157:H7. Despite the low levels of
bacteria detected in the water samples
by membrane filtration,the PCR reaction
for the universal 16s rRNA gene demon-
strated a robust amplification of this gene
fragment (Fig. 2). The PCR assay is a highly
sensitive assay using a DNA amplifica-

tion procedure to detect the presence of
organism-specific genes. This assay is not
quantitative, but the positive reactions
observed (Fig. 2) demonstrate that there
is not a significant level of PCR inhibition
in the reaction. This is a particularly im-
portant point as environmental samples
can contain numerous inhibitors of PCR
such as humic acids and complex polysac-
charides that can lead to false-negative
results being reported. All of the samples
analyzed by PCR were positive for the 16s
rRNA gene,as would be expected. How-
ever, none of the samples was positive for
Salmonella spp. or E coli 0157:H7 by PCR.



Samples subjected to the Salmonella-en-
richment procedure remained negative
for Salmonella spp. by PCR suggesting that
a direct analysis of 25 ml of water by PCR
is not below a particular detection limit,
but that the sample is truly negative for
Salmonella spp.

APHA.2005. Standard methods for the examination
of water andwWastewater,20th Ed.Am. Public Health
Assoc./Am. Water Works AssocJWater Environment
Fed., Washington, DC.

CDC. 2009. Surveillance for foodborne disease

outbreaks United States, 2006. MMWR Morb Mortal

Chang, M.,S.L. Groseclose,A.A.Zaidi, and C.R. Braden.
2009. An ecological analysis ofsociodemographic
factors associated with the incidence ofsalmonel-
losis, shigellosis, and E. coli 0157:H7 infections in US
counties. Epidemiol Infect 137:810-820.

Frenzen, P. D.,A. Drake, and FJ.Angulo.2005.
Economic cost of illness due to Escherichia coli
0157 infections in the United States. J Food Prot 68:

Guo,X., J. Chen, L.R. Beuchat, and R.E. Brackett. 2000.
PCR detection of Salmonella enterica serotype
Montevideo in and on raw tomatoes using primers

derived from hilA. Apple Environ Microbiol 66:5248-

Halatsi, K., I. Oikonomou, M. Lambiri, G. Mandilara,A.
Vatopoulos, and A. Kyriacou. 2006. PCR detection of
Salmonella spp. using primers targeting the quorum
sensing gene sdiA. FEMS Microbiol. Lett..259:201-207.

Lynch, M. F., R.V. Tauxe, and C.W. Hedberg. 2009. The
growing burden offoodborne outbreaks due to
contaminated fresh produce: Risks and opportunities.
Epidemiol. Infect. 137:307-315.

Omiccioli, E., G. Amagliani, G. Brandi and M. Magnani.
2009. A new platform for Real-Time PCR detection of
Salmonella spp., Listeria monocytogenes and Esch-
erichia coli 0157 in milk. Food Microbiol. 26:615-622.



Monica Ozores-Hampton1, Eric Simonne2, KellyMorgan', Kent Cushman', Shinjiro Sato1,
Chris Albright3, Eric Waldo4, and Amir Polak5
'University of Florida/IFAS,SWFREC, Immokalee, FL, ozores@ufl.edu
2University of Florida/IFAS, Horticultural Sciences Dept., Gainesville, FL
3 Helena Chemical, Ft. Pierce, FL
4Haifa Nutritech, Southeast US
'Haifa Chemicals, Haifa, Israel

Increased environmental concerns and
the development of Best Management
Practices (BMP) for vegetable crops have
emphasized the need to better manage
fertilizer, increase fertilizer efficiency,and
reduce N loss to the environment (Shaviv,
2000). Slow-release and controlled-release
fertilizers (CRF) are recognized in the BMP
manual for vegetables (www.floridaagwa-
terpolicy.com) as one of the main nutrient
BMPs for crops grown with seepage irriga-
tion. Synthetic CRN (controlled-release ni-
trogen) can be separated into two general
groups: 1) those that are slow-release as a
byproduct of a chemical reaction (such as
urea-formaldehyde),and,2) those that are
slow release via a sulfur,wax or resin coat-
ing around the fertilizer prill (Morgan et
al.,2009). If the CRN fertilizer has a release
pattern that matches with crop needs, N
uptake by the growing tomato crop may
become more efficient,thus resulting in
greater yield or reduced need for fertilizer
N (Shaviv, 2000; Simonne and Hutchinson,
2005). Additionally,if CRN can be applied
as a pre-plant application,the need for
multiple applications of soluble N fertil-
izer under leaching rain events would be

eliminated, resulting in reduced production
costs (Hutchison et al., 2003; Hutchison and
Most previous work has focused on use
of sulfur coat urea (SCU) and urea-form-
aldehyde (UF),as they have been in the
fertilizer market for thirty years (Lacascio
and Fiskell, 1979; Csizinszky, 1989; Csizin-
szky et al., 1992; 1993). Recently, research
has evaluated resin-coated products (Du et
al.,2006). In Florida,yields were improved
with CRF compared with multiple soluble
fertilizer application in potato production
(H utchison et al., 2003). However, studies
with tomatoes with older CRF materials
when compared to soluble fertilizer ap-
plication have shown conflicting results
(Csizinszky et al., 1994; Morgan et al., 2003).
Based on available research, benefits of
using CRN fertilizers in tomato production
will come from reduced environmental risk
and savings in production costs (Hutchison
and Simonne,2003). Therefore, testing is
needed to determine sources, rate and
release pattern of N under south Florida
growing conditions before growers can
adapt these slow-release sources of N as
part of their fertilizer BMP programs.

Four trials were conducted with different
combination of CRN sources, bed place-
ment and N rates with seepage irrigation
in southwest Florida at the University of
Florida, Southwest Florida Research and
Education Center (UF/SWFREC and on
commercial farms in the Immokalee area
on Immokalee fine sand and EauGallie fine
sand, respectively. Both soils have sandy
surface layers that are prone to N03-N
leaching. Seepage irrigation is possible in
this area because vertical water movement
is decreased by an impervious Spodic layer
at an average depth of 3 feet resulting in a
perched water table. In each trial,tomatoes
were grown following industry standards
for production practices (Table 1) and
UF/IFAS recommendations for pest and
disease control (Olson et al., 2006a,b).
Trial 1 CRN sources and rates with
placement in the"hot mix" (Spring
2006).This trial was conducted at UF/
SWFREC, Immokalee, FL (Table 1). We com-
pared three CRN sources applied as a hot
mix with a control of soluble ammonium
nitrate placed in two grooves on the bed
shoulders at rates of 160,230 and 300 Ib/A.
The three CRFs sources were Nitamin


TABLE 1. Summary of cultural practices used in testing controlled-release fertilizers rates and
placement effect on tomato grown with seepage irrigation in Southwest Florida.
Cultural practice Trial 1 Trial 2 Trial 3 Trial 4
SWFREC SWFREC Commercial field Commercial field
Variety Hazera 3073 Florida 47 BHN832 BHN 832
Plant spacing (inch) 18 18 20 20
Bed spacing (feet) 6 6 6 6
Methyl Bromide: 67:33@3551b/A 67:33@3551b/A 50:50 @ 1001b/A 50:50 @ 1001b/A
Mulch Black White SilverVIF2 SilverVIF
polyethylene polyethylene
Planted plot length 30 30 400 400
Harvestplotlength 21 21 17 17
Number of 3 3 3 3
beds in plot
Replications 4 4 3 3
Bed width (inch) 42 42 32 32
Transplant date 20 Feb., 2006 7 Sept., 2006 13 Dec., 2007 23 Oct., 2008
Harvest dates 16 May, 24 May, 27 Nov., 11 Dec.,and 20 12 Mar.,26 Mar.,and 9 3 Feb., 19 Feb.,and 5
and 5June,2006 Dec.,2006 April,2008 Mar.,2009

[granular (23-0-0), methylated urea and
derivatives; Georgia-Pacific Resins, Inc.],
Multicote [polymer-coated urea (40-0-0);
Haifa Chemical Ltd.],and AgroCote [poly-
mer-coated sulfur-coated urea (38-0-0);The
Scotts Company]. At bedding,40 Ib/A of
soluble N (mostly ammonium nitrate),64
Ib/acre P205,64 Ib/acre K20,and a blend of
micronutrients were broadcast incorporated
in the bed as a bottom mix. Total fertilizer
N rates were 200,270 and 340 Ib/acre.
Trial 2 CRN (polymer-coated urea)
release time and rates with placement
in the"bottom mix" (Fall 2006).This trial
was conducted at UF/SWFREC, Immokalee,
FL (Table 1).This trial compared one CRN
source, Multicote [polymer-coated urea
(40-0-0); Haifa Chemical Ltd.],with a 2 or4
month release rate,and the combination
of the two release rates at the rates of 120,
180,and 240 Ib/A total N. Total N rates were
a combination of CRN at 100,150 and 200
and soluble (mostly ammonium nitrate)
at 20,30 and 40 Ib/acre of N broadcast
application (bottom mix) before bedding
and were compared with a control hot mix
consisting of ammonium nitrate (Pro-
Source, Immokalee,FL). The bottom mix
also included 64 Ib/acre P205,64 Ib/acre
K20,and a blend of micronutrients.
Trial 3 CRN sources (polymer-coated
urea), release time mix and rates with
placement in the"bottom mix"(Winter
2007).The trial was conducted in a com-
mercial farm near Immokalee,FL (Table 1).
We compared two CRN sources: Polyon,
[polymer-coated urea (43-0-0),Agrium
Advance Technology,AL],and Multicote
Agri [polymer-coated urea (43-0-0), Haifa
Nutritech,FL],in a combination of 50%
2-month and 50% 4-month time release
and at two N rates of 120 and 170 Ib/acre
of CRN. Total N rates were a combination

of CRN plus 30 Ib/A of soluble N (mostly
ammonium nitrate) applied broadcast (bot-
tom mix) before bedding and compared
to a control hot mix consisting of 200 (IFAS
rate) and 266 (grower rate) Ib/A of ammoni-
um nitrate and 390 Ib/acre of K20 (Howard
Fertilizer, Immokalee,FL). The bottom mix
also included 190 Ib/acre P205,40 Ib/acre
K20,and a blend of micronutrients.
Trial 4 Combination of CRN (polymer
coated-potassium nitrate) rates and
soluble N fertilizer with placement in
the"bottom mix"(Winter 2008). The trial
was conducted in a commercial farm near
Immokalee,FL (Table 1).We compared one
CRN source Multicote Agri [polymer-coated
potassium nitrate (12-0-43), Haifa Nutritech,
FL],a combination of 50% 2-month and
50% 4-month time release at three N rates
50,100 and 150 Ib/acre applied broadcast
(bottom mix) before bedding plus 100
Ib/acre of soluble N (ammonium nitrate)
as a hot mix. The total N treatments were
150,200 and 250 Ib/acre and compared to
a control hot mix consisting of 200 (IFAS)
and 266 (Grower) Ib/acre of N (ammonium
nitrate) and 390 Ib/acre of K20,(Howard
Fertilizer, Immokalee,FL). In all treatments
the bottom mixalso included 100 Ib/acre
P205,40 Ib/acre K20,and a blend of micro-
Data collection. On-farm plots were
clearly marked to prevent unscheduled
harvest by commercial crews. Marketable
green and colored tomatoes were graded
in the field according to USDA specifica-
tions of number and weight of extra-large
(5x6), large (6x6),and medium (6x7) green
and colored fuit (USDA, 1997). Cull fruits
were those blemished or defective and
thus unmarketable. Trial 1 and 2 were ana-
lyzed by SAS as a two factor experiment.
Statistical significance were determined

for product, rate, and the product by rate
interaction.Trial 3 and 4 yield data were
subjected to analysis of variance (ANOVA)
and mean separation using LSD (trial 1) and
Duncan's Multiple RangeTest (trial 2,3 and
4) at the 5% level.

Weather conditions during the trials.
Overall,South Florida weather recorded by
the Florida Automated Weather Network
(FAWN) was hot and dry throughout the
fall,and cool and dry during the spring of
2006 (Table 2). The two winter seasons
were cool and dry with one (3 Jan.) and five
(21-23,Jan.,5 Feb.and 3 Mar.) freeze events
during 2007 and 2008, respectively.
Cumulative rainfall amounts during the
2006,2007 and 2008 seasons were 6,5.1,
8.8 and 2.5 inches for spring,fall,and the
two winter seasons, respectively. The IFAS
tomato fertilizer recommendation (Olson
et al., 2006b) and the BMP manual (FDACS,
2005) allow for supplemental N and K fertil-
izer applications after a qualified leaching
rain,a documented"low" plant nutrient
concentration,and during extended
harvest seasons. Under this provision,30
Ib/acre of N and 20 Ibs/A of K20 can be
added for each qualifying leaching rain
event. Based on rainfalls during these trials,
no supplemental application was justified
in these trials.
In seepage irrigated fields,freeze protec-
tion may be done by raising the water table
near the soil surface. During these trials,
water tables were raised 7 to 9 inches dur-
ing freeze events from depths of 19 to 24
inches prior to the freeze events to a depth
12 to 15 inches during the day freezing
temperatures were expected. After the
threat of freeze has past, the water table
were lowered to the original 19-24- inch
depth. This cultural practice is necessary to
protect the crops in circumstances beyond
the control of the grower. After the surge
in water table, some soluble nutrients may
leach (Sato et al.,2009ab),but this is not
considered a qualified event for supple-
mental fertilizer application.
Trial 1. The interactions between fertil-
izer source and N rate were not significant.
Fertilizer sources had a significant effect
on plant biomass,yield,and leaf tissue
nutrient content. CRN sources produced
significantly lower yields in the extra-large
(5X6), large (6X6),and medium (6X7) size
categories,and total yield,compared with
the soluble control (Table 3). Also,grower
standard treatment, using soluble fertilizers,
produced more biomass and higher leaf



TABLE 2. Summary total rainfall and number of leaching rain events in South Florida during the
2006 and 2008 tomato seasons.
Trial Year Season Temperature Temperature Total Number Possiblez
Min (F) Max (F) rainfall leaching and applied
(inch) rainfalls supplemental
N (Iblacre)
Reported Average Reported Average
1 2006 Spring 38.6 54.0 99.5 93.8 6.0 0 0/0
2 2006 Fall 36.8 53.9 95.7 90.6 5.1 0 0/0
3 2007 Winter 29.4 55.0 89.8 81.6 8.8 0 0/0
4 2008 Winter 24.7 49.1 90.3 78.6 2.5 0 0/0

TABLE 3. Effects of CRN sources and rates incorporated as a hot mix on total tomato yields
combined over four harvests and according to size categories of extra-large (5x6),large (6x6),
medium (6x7), total of all size categories of marketable fruit and unmarketable yield during
Spring 2006 (Trial 1).


N source

Rate (Ib/acre)

Total Marketable YieldY
(25-lb boxes/acre)


Soluble 1,531 a 354 a 333 a 2,218 a 463 a
Nitamin 901 b 197 b 204 b 1,303 b 345 a
Multicote 1,020 b 204 b 207 b 1,431 b 385 a
AgroCote 1,087 b 224 b 214 b 1,524 b 345 a
P value 0.006 0.001 0.001 0.002 0.70

200 1,246 a 280 a 258 a 1,784 a 424 a
270 1,172 a 252 ab 238 a 1,663 a 365 a
340 986 a 202 b 222 a 1,410 a 364 a
P value 0.23 0.05 0.45 0.17 0.31

TABLE 4. Effects of CRN [Multicote, polymer-coated urea (40-0-0)] release time and rates incorpo-
rate as a bottom mix on total tomato yields combined over four harvests and according to size
categories of extra-large (5x6), large (6x6), medium (6x7), total of all size categories of marketable
fruit and unmarketable yield during the Fall season 2006 (Trial 2).

Factor Total Marketable Yield (Boxes/acre)' Culls Y
N source Rate (Ib/acre) 5/6 6/6 6/7 Total
Soluble 2,041 a 325 a 410 a 2,776 b 319 a
2-mo/4-mo (Multicote) 2,213 a 328 a 448 a 2,989 ab 276 a
2-month (Multicote) 2,293 a 379 a 502 a 3,179 a 282 a
4-month (Multicote) 2,304 a 387 a 511 a 3,201 a 320 a
P value 0.19 0.50 0.53 0.10 0.18

120 2,093 a 333 a 462 a 2,888 a 293 a
180 2,,209 a 315 a 445 a 2,950 a 297 a
240 2,340 a 416 a 516 a 3,271 a 308 a
P value 0.12 0.07 0.41 0.05 0.79
Linear Contrast (rate)w ns ns ns ns

N content than any of the CRN fertilizers
treatments (data not shown). Nitrogen
rate had little effect on plant growth or
performance. It can be concluded that CRN
fertilizers are not well suited to the type of
placement used in this study. More specifi-
cally,CRN products appeared ineffective
when used as a"hot mix"and placed in

grooves at the top and outside edges of
the plant bed. Hence, CRN were broadcast
incorporated on the cold mix in the other
Trial 2. There were no significant interac-
tions among release time and N rates
(Table 4). Higher total marketable yield (all
harvest and size combined) were produced

with the 2-month or 4-month release
materials alone than with the soluble N
treatment, but the yields with the 50-50
2-month + 4-month combination treat-
ment were not significantly different from
those with either release time alone or the
soluble-N treatments (P < 0.10). Total X-
large (5X6), large (6X6), medium (6X7),and
unmarketable (culls) were not significantly
affected by N release time (2 and 4-months
or the combination of both products).
Total marketable yield (all harvest and size
combined) increased linearly as N rate
increased from 120 to 240 Ib/acre (P< 0.05).
Total X-large (5X6), large (6X6), medium
(6X7),and unmarketable (culls) were not
significantly affected by N rate.
Trial 3. Soluble fertilizer application of
200 (IFAS) and 266 (Grower) Ib/acre of N
resulted in higher extra-large (5X6) fruit at
first harvest than the two CRN products at
120 Ib/acre CRN rate (150 Ib/acre of total N;
[Table 5; P < 0.05). Soluble fertilizer applica-
tion at 266 Ib/acre (grower) rate produced
greater total yield (three harvest and sizes
combined) than the two CRN products
at 120 Ib/acre CRN rate (150 Ib/acre of
total N) but these differences were not
significant (P < 0.10). There were no dif-
ferences between 266 and 200 Ib/acre or
200 Ib/acre and the CRN products in total
yields (P < 0.10).Yield reduction with both
CRN products at 150 Ib/acre of total of N
extra-large (5X6) fruit at first harvest and
total yield was probably due to a smaller
plant biomass and lower petiole sap
N03-N concentrations probably induced
by lower N rates (compared with IFAS and
grower rates) and ammonium (NH4-N)
toxicity (Figure 1). High soil NH4-N levels
of 32 ppm in the center of the bed at 35
days after planting (DAP) compared with
8 ppm from soluble N grower rate of 266
Ib/acre (Figure 1). Ammonium toxicity may
occur when fertilizers containing urea are
applied to cold wet soils that have been
fumigated. The conversion of NH4-N to
N03-N (nitrifcation) is carried out by soil
nitrifying bacteria that may be absent due
to soil fumigation (methyl bromide/chlo-
ropicrin). Secondly, the cool wet soils with
poor aeration due to freeze protection
practices (Table 1) would lead to increased
soil ammonium retention. Also,the utiliza-
tion ofVIP high barrier plastic films to
reduce fumigation rates may have trapped
volatile ammonium in the soil.Ammonium
toxicity can produce symptoms similar to
phosphorous deficiency, primarily reducing
plant biomass and causing extreme toxicity
symptoms that can lead to plant mortality.


TABLE 5. Effects of CRN [Polyon and Multicote@ Agri polymer-coated urea (43-0-0)] sources and
rates incorporated as a bottom mix on total tomato yields over 3 harvests and according to size
categories of extra-large (5x6), large (6x6), medium (6x7), total of all size categories of marketable
fruit and unmarketable yield during winter 2007 (trial 3).z

N program (Ib/acre) Total Marketable Yield (Boxes/acre)
First harvest Second harvest
N CRN Soluble N Total N 5/6 6/6 6/7 Total Culls 5/6 6/6 6/7 Total Culls
Grower 0 266 266 492a 197b 138 828 108 981 652 623 2,256 421
IFAS 0 200 200 515a 233b 128 877 124 984 622 578 2,184 493
Polyon 120x 30 150 370b 304a 154 828 98 672 632 596 1,900 374
Multicote 120x 30 150 434b 282a 174 889 125 810 586 500 1,896 372
P value 0.03 0.04 0.68 0.51 0.52 0.13 0.51 0.19 0.09 0.25
x120 LB/A = 60 LB/A OF A 2-MONTH + 60 LB/A OF A 4-MONTH CRN
FIGURE 1. Center of the bed soil (NH4-N) ammonium content at four inches depth during winter
2007 season.

140 OO4' Grower (266 Ib/acre)
-4--WIFAS (200 Ib/acre)
120 A Polyon-150 Ib/acrez
100 -X- Multicore-150 Ib/acre
E / -0-- Polyon-200 Ib/acre
0 Multicore-200 Ib/acre
60 c
Z 40
S S *

12. 19 I. 3 I. 18 2, 2 2, 17 3. 3 3. 18 4. 2 4. 17
2007 2008 2008 2008 2008 2008 2008 2008 2008
TABLE 6. Effects of combination of CRN [Multicote Agri polymer-coated potassium nitrate (12-0-
43), Haifa Nutritech, FL] rates and soluble N fertilizer on total tomato yields over three harvests
and according to size categories of extra-large (5x6), large (6x6), medium (6x7), total of all size
categories of marketable fruit and unmarketable yield during winter 2008 (trial 4).z

N program (lb/acre) Marketable Yield (Boxes/acre)
N program (Ib/acre) --------i --- - --------
First harvest Second harvest
CRN Soluble N Total N 5/6 6/6 6/7 Total H1+H2 5/6 6/6 6/7 Total Culls
Bottom Hot mix Total
0 255 255 783 359 138 1,280 2,042ab 1,152 837 625 2,614 404
0 200 (IFA) 200 861 286 95 1,243 2,119a 1,182 737 739 2,658 350
50 100 150 791 325 124 1,240 2,042ab 1,170 767 624 2,561 347
100 100 200 877 284 108 1,269 2,209a 1,296 740 580 2,616 399
150 100 250 672 282 117 1,070 1,852b 1,024 703 716 2,443 360
P value 0.25 0.35 0.60 0.08 0.05 0.40 0.33 0.10 0.38 0.82
Contrast Linear (CRN only) 0.23 0.33 0.80 0.08 0.07 0.31 0.30 0.33 0.34 0.83

Higher CRN rate of 170 Ib/acre or 200 Ib/acre
of total N resulted in plant mortality of 54%
for Polyon and 29% for Multicote probably
due to higher NH4-N soil concentration in
the center of the bed of 91 and 75 ppm,
respectively,as compared of 8 ppm NH4-N
where the soluble N grower rate of 266
Ib/acre 35 DAP was applied (Figure 1).
Trial 4. Soluble fertilizer application 200
(IFAS), 266 (Grower) Ib/acre, CRN (Multicote)
at 50 and 100 Ib/acre N rate or 150 and 200
Ib/acre of total N, respectively, resulted in
higher total first harvest than CRN (Multi-
cote) at 150 Ib/acre N rate or 250 Ib/acre of

total N [Table 6 (P< 0.10)].
Soluble fertilizer application 200 (IFAS) and
CRN (Multicote) at 100 or 200 Ib/acre N rate
resulted in higher total first and second
harvest (all sizes combined) than CRN (Mul-
ticote) at 150 Ib/acre N rate or 250 Ib/acre of
total N (Table 6; P < 0.10). There was no re-
sponse to N treatment by other tomato size
categories in any harvest. Total first harvest
(all sizes combined) and total first and sec-
ond harvest (all sizes combined) tended to
increase linearly as CRN (Multicote) rate in-
creased from 50 to 150 Ib/acre of N or 150 to
250 Ib/acre of total N (P< 0.10).There was no

response to CRN treatment by other tomato
size categories in any harvest. Combina-
tion of 50 or 100 Ib/acre of CRN (Multicote)
and 100 Ib/acre of soluble N fertilizer can
produced similar results than 100% soluble
N fertilizer during winter season.

a.When different CRN sources were tested
as a"top mix'their performance was lower
than that of the control soluble fertilizer
(trial 1) most likely because their placement
in the bed reduced the rate of N released
into the soil thereby reducing plant growth
and yield. CRN products may perform better
when placed in the bed and incorporated
into the soil so the CRN particles are in close
contact with soil and soil moisture.
b.In the Fall of 2006,one CRN source
(polymer-coated urea) was thoroughly
mixed with the soil during bedding in what
is commonly called the"bottom mix"(Trial
2). The CRN (polymer-coated urea) per-
formed well in this placement, with yields
greater than or equal to the control or
soluble N treatments.
c.Trial 3 illustrated the need for more
research regarding the use and placement
of polymer-coated urea on mulched crops
during the winter in South Florida because
of risks associated with ammonium toxicity.
In this case,it is possible an extreme cold
temperature event, saturated soil condi-
tions resulting from the use of surface water
as freeze protection,and the reduction of
microbe activity in converting NH4-N due to
fumigation (methyl bromide/chloropicrin)
all worked to increase the risk of plant NH4-
N toxicity. In our trial,two CRN products at
120 Ib/acre (150 Ib/acre of total N) resulted
in lower yield in major tomato categories
compared with soluble N probably due to
lower than optimal N rate and high NH4-N
soil content (32 ppm at the center of the
bed). Higher CRN rates of 170 Ib/acre or 200
Ib/acre total N of the same two products
resulted in plant mortality of 29% and 54%,
probably due to higher NH4-N soil concen-
tration in the center of the bed of 91 and 75
ppm, respectively. This further indicates op-
timum performance of urea-based CRN fer-
tilizers in Fall and Winter tomatoes in South
Florida appears to depend on avoiding
fertilizer placement and other cultural prac-
tices which lead to temperature extremes or
water saturation. Optimal soil temperatures
with a minimum of 50oF and maximum
of 94F are suitable for the conversion of
NH4-N to N03-N (a process called nitrifica-
tion; Sabey et al., 1956),therefore, extreme
temperatures can lead to an accumulation



of excessive and damaging NH4-N in the
soil, especially when used under VIF-type
film. Utilizing other CRN sources,such as
polymer coated potassium nitrate, may lead
to better results.
d.CRN as polymer-coated potassium
nitrate (trial 4) can be a more suitable source
of N for tomato production during the
winter in South Florida to minimize the risk
of high soil NH4-N.Also,the combination
of 50 or 100 Ib/acre of CRN as (polymer-
coated potassium nitrate) broadcast in the
bed and 100 Ib/acre of soluble N fertilizer as
'hot mix'pre-plant produced comparable
yields in the major tomato categories (total
first harvest, total first and second harvest
combined,and total harvest (all sized and
harvest combined). Based on these results,
the use of polymer-coated potassium nitrate
needs to be investigated in multiple winters
and other seasons.*

CsizinszkyA.A. 1994.Yield response of bell pepper and
tomato to controlled release fertilizer on sand.J. Plant

Csizinszky, A. A., C. D. Stasley, and G. A. Clark. 1993.
Evaluation of controlled-release urea for fresh-market
tomato. Proc. Fla. State Hort.Soc. 106:183-187.

Csizinszky, A. A., G.A. Clark and C. D. Stasley. 1992.
Evaluation of methylene urea for fresh-market tomato,
with seepage irrigation. Proc. Fla. State Hort. Soc.


Csizinszky,A.A. 1989. Effect of controlled (slow) release
nitrogen sources on tomato, Lycopersicon esculentum
Mill. cv. 'Solar Set: Proc. Fla. State Hort. Soc. 102:348-

Du, C.,J.Zhou, andA. Shaviv. 2006. Release character-
istic of nutrients from polymer-coated compound con-
trolled release fertilizers. J. Polym. Environ. 14:223-230.

FDACS. 2005. Florida Vegetable and Agronomic Crop
Water Quality and Quantity BMP Manual. Florida
Department ofAgriculture and Consumer Services

Hutchinson, C., E. Simonne, P. Solano,J. Meldrum, and
P. Linvingston-Way. 2003. Testing of controlled release
fertilizers programs for seep irrigated Irish potato
production. J.Plant Nutr. 26:1709-1723.

Hutchinson, C. M. and E.H. Simonne. 2003. Controlled-
release fertilizer opportunities and cost for potato
production in Florida, EDIS HS-941, http://edis.ifas.ufl.

Locascio, SJ. andJ.G. Fiskell. 1979. Pepper response
to sulfur-coated urea, mulch and nitrogen rate. Proc.
Fla. State Hort. Soc. 92:112-115.

Morgan, K., K. Cushman, and S. Sato. 2009. Release
mechanisms for slow- and controlled- release fertil-
izer and strategies for their use in vegetable produc-
tion. J. Hort. Technology 19(1):10-12.

Olson, S.M., E.H. Simonne, W.M. Stall, K.L. Pernezny,
S.E. Webb, T.G. Taylor, SA. Smith, and D.M. Parmenter.

2006a. Pepper production in Florida, pp. 331-343
In:S.M. Olson and E.Simonne (Eds.) 2006-2007
Vegetable Production Handbook for Florida, Vance
Pub., Lenexa, KS.

Olson, S.M., W. M. Stall, M.T. Momol, S.E. Webb, T.G.
Taylor, S.A. Smith, E. H. Simonne, and E. McAvoy.
2006b. Tomato production in Florida, pp. 407-426
In:S.M. Olson and E.Simonne (Eds.) 2006-2007
Vegetable Production Handbook for Florida, Vance
Pub., Lenexa, KS.

Sato, S, K. T. Morgan, M. Ozores-Hampton, and E.H.
Simonne. 2009a. Spatial distributions in sandy soils
with seepage irrigation: Nitrogen. Soil Sci.Soc.Am.J.

Sato, S., K.T. Morgan, M. Ozores-Hampton, and E.H.
Simonne. 2009b. Spatial distributions in sandysoils
with seepage irrigation: Phosphorus and potassium.
Soil Sci.Soc.Am.J.73(3):1053-1060.

Simonne, E.H. and C.M. Hutchinson. 2005. Controlled
release fertilizer for vegetable crops: Teaching new
tricks to an old dog. HortTechnology 15(1):14-24.

USDA. 1997. United States standards for grades of
fresh tomatoes. Agr. Markt. Serv. http://www.ams.

Savey B. R., W.V. Bartholomew, R. Shaw andJ. Pseek.
1956. Influence of temperature on nitrification in soils.
Soil Sci. Soc.Am.J. 20(3)357-360.

Shaviv, A. 2000. Advances in controlled release fertil-
izers. Adv.Agron. 71:1-49.


Bielinski M. Santos and Camille E. Esmel
University of Florida/IFAS, GCREC, Wimauma, FL, bmsantos@ufl.edu

Sulfur (S) is an essential plant nutrient for
crops and it is required for the synthesis of
the amino acids cysteine and methionine,
which are building blocks of certain plant
proteins and enzymes. In the past, S was
supplied indirectly in two ways:a) through
the application of fertilizers, such as triple
superphosphate; and b) through atmo-
spheric deposition from acid rain resulting
from fossil fuel burning. However,this
situation has changed during the last two
decades. Granular and liquid fertilizers no
longer contain high amounts of sulfates,
and stringent federal and state environ-
mental regulations have reduced the inci-
dence of acid rain.Therefore,S deficiencies

are more likely to occur today.
Typical S deficiencies are often
confused with those of other deficient
elements,such as nitrogen (N),and they
show as generalized leaf yellowing or light
green foliage with weak plants. These
symptoms frequently confound the ability
of growers, researchers and Extension
personnel to diagnose correctly S defi-
ciencies. This element occurs in the soil in
both organic and inorganic forms, but in
most soils, the majority of S is in diverse
organic forms. Most plants absorb S
through the roots as the inorganic sulfate
(S04) form,although limited amounts can
be absorbed through the leaf stomata as
the gas S02.

Tomato production in Florida mostly
occurs on deep Spodosols (fine sand) with
low organic matter (<2%) content. These
soils have low capacity for S retention and
thus S leaching is likely to occur before
root absorption takes place. Preliminary
field observations indicated that several
crops, including tomato, bell pepper and
strawberry could respond to S fertilization,
increasing plant vigor and marketable
yields. But more research is needed on the
subject. Hence,a four-year project was ini-
tiated in 2005 at the Gulf Coast Research
and Education Center in Wimauma Florida,
to:a) determine the tomato response to
S fertilization, b) revaluate its sufficiency
range, c) reformulate application rates, d)


examine the effect of S-containing irriga-
tion water on the total S contribution for
tomato,and e) determine a valid analytical
test to determine S availability in soils.

Effects of S source on tomato.This first
study was conducted twice between 2006
and 2007 and examined the impact of
several S-containing fertilizer sources on
tomato yields and leaf S concentrations.
Fertilizer-source treatments were: a) am-
monium nitrate (AN; 34% N) at a rate of
300 Ib/acre of N; b) AN + potassium sulfate
(PS; 23% S and 55% K) at rates of 300 +
343 Ib/acre of N and S; c) ammonium
sulfate nitrate (ASN; 26% N and 14% S) at a
rate of 300 + 343 Ib/acre of N and S; and d)
a non-treated control. Muriate of potash
(KCI,60% K) was used to balance total K
amounts in each treatment to ensure that
this nutrient was non-limiting. Fertilizers
were applied 21 days before transplant-
ing on two,3-inch-deep, 14-inches-apart
bands on bed tops. Planting beds were 32
inches wide at the base, 28 inches wide at
the top,8-inch high,and 5-ft apart. Fin-
ished beds were fumigated with methyl
bromide plus chloropicrin (67:33 v/v) at a
rate of 175 Ib/acre to eliminate soilborne
diseases, nematodes,and weeds. Beds
were covered with 0.6-mil-thick silver-on-
black polyethylene mulch,and drip irriga-
tion tubing was buried 1 inch deep in the
bed center. 'Florida 47'tomato transplants
were established 2-ft apart on single rows
on the center of each bed. Irrigation was
supplied via subsurface irrigation at an
approximate rate of 8,000 gal/acre/day,
and the soil was maintained at field
capacity. The water table was maintained
between 18 and 24 inches deep and
constantly monitored with observations
wells located in the fields. Plant nutrients,
other than N and S,were supplied under
non-limiting conditions. The four treat-
ments were arranged in a randomized
complete block design with four replica-
tions. Experimental units were 30-ft long
with a 10-ft long non-treated buffer zone
at the end of each plot. Recently mature
leaves were collected from each plot 12
weeks after transplanting (WAT) to deter-
mine foliar S concentration. Tomato fruits
were harvested twice (10 and 12 WAT) and
graded as marketable or non-marketable.
Data were analyzed with General Linear
Model procedure of SAS to determine
treatments effects (P=0.05) and treatment
means were separated with single degree-
of-freedom orthogonal contrasts.

TABLE 1. Effects of sulfur (S) fertilizer sources on tomato foliar S concentrations and marketable
Fertilizer sources N rates S rates Foliar S concentrations Marketable yields
(Ib/acre) (%) (ton/acre)
Control 0 0 0.53 b 12.4 c
AN 300 0 0.55 b 18.7 b
AN + PS 300 343 0.79 a 28.2 a
ASN 300 343 0.72 a 27.5 a
FIGURE 1. Effect of preplant sulfur (S) application rates on the foliar S concentration
in mature tomato leaves at 5 weeks after transplanting.



C 0.54


after ti
" 4.6
>- 4.2
M 4.0
2 3.8




y = 0.54 + 0.027*(1- 0.95x), R2 = 0.90
3o S rate vs. S concentration
0 50 100 150 200 250
Sulfer Rate (Ibs/A)

E 2. Effects of preplant sulfur (S) application rates on the early tomato yields at 10 weeks

y = 4.83/(1 + exp(-(-1.20)/1.20))), R2 = 0.88
0 Tomato yield

Sulfer Rate (Ibs/A)

Fertilizer treatments affected tomato
foliar S concentration and marketable fruit
weight. Plots treated with either rate of
AN or non-treated had the lowest foliar
S concentration, ranging between 0.55%
and 0.53% (Table 1). However, plots treat-
ed with S-containing fertilizers caused
significant foliar S concentration increases
when compared with the non-treated
control and AN-treated plots. Average S
concentration was about 0.74%, which
was 40% higher than the concentration in
non-treated control plots.There were no
significant differences on foliar S concen-
tration between AN + PS and ASN when
compared within the same rates (Table 1).
Therefore,adding S to the fertilization pro-

150 200

grams, regardless of S sources, increased S
Marketable fruit weight followed a simi-
lar pattern as that for S concentration in
the tomato leaves (Table 1).There were no
significant marketable yield differences in
plots treated with either AN + PS or ASN,
suggesting that different S sources caused
no different response on tomato produc-
tion. Average marketable yield ranged
between 27.5 and 28.2 ton/acre in the
S-treated plots. In contrast, average yield
in the AN-treated plots was 18.7 ton/acre,
which was 44% and 42% less than the
yields in the AN + PS and ASN-treated
plots. The AN-treated plots had higher
yields than the non-treated control,which



can be attributed to the increased N rates.
It has been indicated that the suffi-
ciency S range for tomato is between 0.3%
and 0.8% on a dry weight basis,which
appears to be excessively wide for specific
S recommendations in tomato. In this
case, there was a positive tomato yield
response as concentration increased from
about 0.53% in the non-treated control to
0.7% in the S-treated plots, demonstrating
that application of S in tomato fertilization
programs is essential to increase market-
able yields.
Influence of S rates on Tomato. This sec-
ond study was conducted twice between
2008 and 2009 to determine the appro-
priate preplant S rate needed to increase
tomato yields. Similar cultural practices

were used as previously described. Ele-
mental S (90% S) was used as the preplant
fertilizer source and it was applied on bed
tops between 15 days before transplant-
ing as described for the previous study.
Application rates were 0,25,50,100,150,
and 200 Ib/acre of S. Other plant nutri-
ents were supplied under non-limiting
conditions. Foliar S concentration was
measured between 4 and 5 WAT using
recently mature leaves. Tomato fruits were
harvested on 10 and 12WATand graded
as marketable or non-marketable. Data
were analyzed using regression analysis.
There was a significant effect of S rates
on foliar S concentrations and early yields,
but not on total yields (data not shown).
Foliar S concentration increased sharply

from 0 to 50 Ib/acre of S, with no sig-
nificant changes afterwards (Fig. 1). Early
total yields increased with the applica-
tion of 25 Ib/acre of S,with no significant
early yield response between 25 and 200
Ib/acre of S (Fig. 2). These results indicated
that there is a significant response of to-
mato to preplant S fertilization, regardless
of the S source utilized. Growers seeking
to include S into their current fertilization
programs might need to explore using
between 25 and 50 Ib/acre of S,depend-
ing on the preplant application procedure
and considering either in-bed or broad-
cast rates of this nutrient. More research is
needed to validate these results in large-
scale plots in grower fields. *




Moshe Lapidot' and David Levy2
'Dept. of Vegetable Research, Institute of Plant Sciences, Agricultural Research Organization,
Volcani Center, Bet Dagan 50250, Israel, lapidotm@volcani.agri.gov.il
2Hazera Genetics, Mivhor, M.P. Lachish Darom, 79134, Israel

Tomato Yellow Leaf Curl Virus (TYLCV)
is currently one of the most devastating
viruses of cultivated tomatoes in tropi-
cal and subtropical regions. Although
originally found in the eastern Mediterra-
nean (Cohen and Harpaz, 1964),it is now a
worldwide problem in tomato cultivation
(Polston and Anderson, 1997; Moriones
and Navas-Castillo, 2000). The virus is a
monopartite begomovirus, transmitted by
the whitefly Bemisia tabaci (Gennadius)
whose severe population outbreaks are
usually associated with high incidence of
the disease. Control measures in infected
regions are traditionally based on limiting
vector populations. Chemical control
has been only partially effective, espe-
cially under high disease pressure,and in
addition to its deleterious effects on the
environment, the vector has been shown
to develop pesticide resistance. The use
of physical barriers such as fine-mesh
screens and UV-absorbing plastic sheets
and screens has become widespread in
the Mediterranean basin as a means of

crop protection (Antignus etal. 2001).
However,these screens also result in
overheating and poor ventilation. Genetic
resistance in the host plant is the best
defence against whitefly-transmitted
viruses,since it requires no chemical input
and/or plant seclusion and may be stable
and long-lasting. Thus,the best way to
reduce the spread ofTYLCV is by breeding
tomatoes that are resistant or tolerant to
the virus (Lapidot and Friedmann, 2002).
Over the last 25 years, extensive effort
has been invested in breeding tomato
cultivars resistant to TYLCV. Since all culti-
vars of tomato (Lycopersicon esculentum)
are extremely susceptible to TYLCV, wild
Lycopersicon species were screened for
their response to the virus to identify
genes for resistance. Breeding programs
have been based on the transfer of resis-
tance genes from accessions of wild ori-
gin into the cultivated tomato. However,
progress in breeding forTYLCV resistance
has been slow, due in part to the complex
genetics of the resistance and the pres-
ence of interspecific barriers between the

wild and domesticated tomato species
(Lapidot and Friedmann, 2002).
Another setback in the development
ofTYLCV resistance is that while most
screening assays rely on severity ofTY-
LCV-induced disease symptoms,the most
relevant evaluation of resistance level is
TYLCV-induced yield reduction (Lapi-
dot et al. 1997,2006). Thus it is recom-
mended that in addition to monitoring
symptoms, the effect of infection on total
yield and yield components be tested
and compared to that in equivalent, non-
infected plants. Usually,tests comparing
different varieties are carried out under
field inoculation,and no comparison is
made to the full yield potential of unin-
fected plants,which has a direct bear-
ing on the yields of the infected plants.
Nevertheless, such expensive and time-
consuming tests can only be carried out
on the most promising resistant varieties,
and not on segregating populations.
Another obstacle in the development
of TYLCV resistance has been the lack of
a standard method for the assessment of


resistance. Variability in assay conditions
has led to contradictory results, where
different resistance levels have been
attributed to the same genetic sources
(Pico et al., 1998;Vidavsky et al., 1998).
The response of a plant to infection
by a pathogen may be affected by test
conditions such as temperature, light,
growth conditions, inoculation pres-
sure and plant age (or developmental
stage) at the time of infection. This latter
phenomenon has been referred to as
age-related or mature-plant resistance
(Loebenstein, 1972). In some instances, it
has been shown that mature plants resist
or tolerate virus infection much better
than plants infected at an early stage of
development, leading to what appears to
be increased viral resistance (Garcia-Ruiz
and Murphy, 2001; Moriones et al. 1998).
In this study,we tested for the possible
effects of plant age on the expression
of genetic resistance to TYLCV. Tomato
plants expressing different levels of resis-
tance to TYLCV were inoculated at three
different ages-1 4,28 and 45 days after
sowing (DAS). Resistance was assayed
mainly by comparing yield components
of inoculated plants to those of control,
non-inoculated plants of the same line or

Virus and whitefly maintenance. Culture
of the Israeli isolate ofTYLCV (GenBank
Acc. No.X15656) were maintained in to-
mato (Lycopersicon esculentum L.) in an in-
sect-proof greenhouse. Whitefly (Bemisia
tabaci, biotype B) colonies were reared
on cotton (Gossypium hirsutum L.) plants
grown in muslin-covered cages main-
tained inside an insect-proof greenhouse.
Plant material. Lines: ATYLCV-susceptible
'Marmande'type tomato line, Rehovot-13
(R-13; Hazera Genetics Ltd., Brurim, Israel),
and a highly TYLCV-resistant tomato line,
TY-199 (Volcani Center),were used.
F1 hybrids.The TYLCV-susceptible
tomato, 144,and TYLCV-resistant to-
matoes-3193,3205 and 3209 (Hazera
Genetics Ltd.),Tyjoco (Sluis & Groot/Syn-
genta, Enkhuizen,The Netherlands) and
Anastasia (Bruinsma Seeds, Enkhuizen,The
Netherlands),were used.
Test plants were sown in 128-cell Todd
Planter Flats (also known as"speedling"
trays) and kept in the trays for 30 days
until transplanted to the field.
TYLCV inoculation. Adult whiteflies were
provided a 48-h acquisition access period

(AAP) on TYLCV-infected tomato source
plants. Following the AAP,whiteflies were
allowed a 24-h inoculation access period
(IAP) on tomato test plants. Tomato plants
inoculated at 14 and 28 DAS were inocu-
lated in the greenhouse,whereas plants
inoculated at 45 DAS were inoculated in
the field.
Greenhouse inoculation.To ensure 100%
infection, inoculation was performed
at a density of about 50 whiteflies per
plant. The different tomato varieties were
inoculated at 14 or 28 DAS. Control, non-
inoculated plants of the same varieties
were exposed to virus-free whiteflies for
24 h. Following the IAP, whiteflies were
removed by treating plants with imidaclo-
prid (Confidor, Bayer, Leverkusen, Ger-
many). The plants were maintained in an
insect-proof greenhouse at 26-32oC prior
to transplant to the field at 30 DAS.
Inoculation in the field. Adult whiteflies
were provided a 48-h AAP on TYLCV-
infected tomato source plants,after
which the source plants containing
the whiteflies were moved into sealed
buckets. In the field, the target plants for
inoculation were covered with non-wo-
ven polypropylene (Agril) sheets (Sodoca,
Biesheim, France) mounted on a wooden
frame. The buckets were taken to the
field, positioned under the Agril sheets
and then opened to release the white-
flies. The whiteflies were allowed a 24-h
IAP on the test tomato plants followed
by application of imidacloprid. The Agril
sheets were removed 24 h after imidaclo-
prid application.
TYLCV symptom-severity rating.
Symptom development was evaluated ac-
cording to the symptom-severity scale de-
scribed by Friedmann etal.(1998):0 = no
visible symptoms, inoculated plants show
same growth and development as non-in-
oculated plants; 1 = very slight yellowing
of leaflet margins on apical leaf; 2 = some
yellowing and minor curling of leaflet
ends; 3 = a wide range of leaf yellowing,
curling and cupping,with some reduction
in size, but plants continue to develop; 4 =
very severe plant stunting and yellowing,
pronounced leaf cupping and curling,and
plant growth stops. Symptom severity
was evaluated in the field,5 weeks after
transplanting. Plant height was measured
a month later.
Field trial. Following controlled in-
oculation in the greenhouse, plants were
treated with imidacloprid before estab-
lishement in the field in April,and grown

through the spring and summer seasons.
Plants of each variety were planted in
paired rows-inoculated and non-in-
oculated (control), on 1-m wide beds,
five plants per row. The within-row and
between-row spacing were 0.5 and 1.2
m, respectively. Each pair of rows served
as a replicate for the experiment,and a
total of 10 randomly distributed replicates
were planted in the field. Imidacloprid
was applied through the drip-irrigation
system on 4 and 8 weeks after transplant-
ing. Fruits were picked three times: in the
first and second harvests, only mature-red
fruits were collected; in the third harvest,
all mature-red and immature green fruits
were collected. Culls were discarded. The
following parameters were assayed:total
yield, total number of fruits and average
fruit weight. Data were taken per row and
were averaged for all rows.

Effect of age on TYLCV-induced yield re-
duction. To test the effect of plant age on
genetic resistance to TYLCV, plants were
inoculated at 14,28 or 45 days after sow-
ing (DAS). At 14 and 28 DAS the plants
were inoculated in the greenhouse,and
at 30 DAS the plants were transplanted in
the field. Inoculation at 45 DAS was done
in the field,following transplanting. The
highest level of resistance,as reflected
by the lowest yield reduction induced by
TYLCV, was expressed by the resistant line
TY-199 (Table 1). Following inoculation at
14 DAS (the first true leaf stage),TY-199
plants showed no disease symptoms, but
nonetheless produced only 45.5% of the
yield of the non-inoculated control plants.
TY-199 was followed by the F1 hybrid
3205 which produced 42% of the yield of
its non-inoculated control.The resistant
F1 hybrids 3193,3209 and'Anastasia'
expressed practically the same level of re-
sistance,which was much lower than that
expressed byTY-199 and 3205, producing
27.4%,26.4% and 25.4%, respectively, of
the yield of their non-inoculated counter-
parts. Of all the resistant varieties tested,
'Tyjoco'showed the lowest level of resis-
tance following inoculation, producing
only 18% of the yield of its non-inoculated
control (Table 1). However,all the resistant
varieties performed much better than the
two susceptible controls, R-13 and 144,
both of which barely produced any fruit
following inoculation (0.0% and 2.6%,
respectively, compared to the yield of their
non-inoculated counterparts). The TYLCV-



TABLE 1.The effect of plant age at time of inoculation with Tomato Yellow Leaf Curl virus on yield
components of selected tomato cultivars.
Cultivar Plant age at inoculation Symptom severity Plant height Yield Fruit weight
(DAS)z scoreY (cm)x (kg/plant) (g/fruit)

R-13 Non-inoculated 0.0 131.0 a 4.2 a 128.5 a
14 4.0 47.8 b 0.0 b 86.3 b
28 4.0 73.5 c 0.1 c 70.3 c
45 4.0 75.6 c 0.9 d 85.4 c
144 Non-inoculated 0.0 150.0 a 6.7 a 94.7 a
14 4.0 52.5 b 0.2 b 52.2 b
28 4.0 85.5 c 0.6 c 60.0 b
45 4.0 92.7 c 1.4 d 68.2 c
TY-199 Non-inoculated 0.0 164.4 a 4.4 a 80.1 a
14 0.1 144.5 b 2.0 b 77.6 a
28 0.1 160.0 a 3.1 c 74.8 a
45 0.0 157.8 a 4.0 a 76.7 a
3205 Non-inoculated 0.0 159.4 a 6.7 a 65.6 a
14 0.7 128.6 b 2.8 b 60.0 a
28 0.3 149.4 c 4.3 c 62.0 a
45 0.0 153.8 a,b 5.5 d 61.7 a
3193 Non-inoculated 0.0 161.9 a 6.2 a 106.0 a
14 1.1 121.9 b 1.7 b 96.7 a
28 1.0 145.0 c 3.4 c 103.8 a
45 0.4 142.5 c 4.4 d 98.4 a
3209 Non-inoculated 0.0 157.5 a 7.2 a 155.9 a
14 1.3 131.3 b 1.9 b 120.2 b
28 1.3 146.3 a,b 3.3 c 118.1 b
45 0.3 151.3 a 5.5 d 146.2 a
Tyjoco Non-inoculated 0.0 154.4 a 6.1 a 95.8 a
14 2.3 113.8 b 1.1 b 62.7 b
28 1.9 131.1 c 2.7 c 75.5 c
45 1.4 142.9 d 3.9 d 74.3 c
Anastasia Non-inoculated 0.0 161.9 a 5.9 a 103.6 a
14 2.4 111.3 b 1.5 b 88.9 b
28 2.2 127.5 c 2.3 c 91.4 b
45 1.9 140.0 d 3.5 d 89.3 b
IDAS = days after sowing; YSymptom severity was evaluated in the field, 5 weeks after transplanting; Xplant height was measured
a month later.
Means with different letters differ significantly at P < 0.05 when analyzed by one-way ANOVA.

induced yield reduction was mainly due
to the strong reduction in the number of
fruits per plant,although in the case of
the susceptible varieties,there was also
a strong reduction in fruit size-ranging
from 57% of the size of the control fruits
for 144 to 66.5% of the size of the control
fruits for R-13. Only two of the resistant
varieties,'Tyjoco'and 3209,suffered a
significant reduction in fruit size following
inoculation:'Tyjoco'fruit size was 69% of
that of its non-inoculated controls,and
3209 fruit size was 77% of that of its non-
inoculated controls. The other resistant
varieties suffered minor reductions in fruit
size due to TYLCV inoculation, ranging

from'Anastasia'which lost only 14% of its
fruit size to TY-199,3205 and 3193, which
showed no significant reduction in fruit
size at all (Table 1).
Disease-severity score was in essence
correlated to yield reduction: the higher
the score, the higher the yield reduction.
Both susceptible varieties had the high-
est disease severity score of 4, followed
by'Anastasia'and'Tyjoco'(2.4 and 2.3,
respectively), 3209 and 3193 (1.3 and 1.1,
respectively),and finally 3205 with 0.7
and TY-199 which showed practically no
disease symptoms (Table 1).
Plant heights of the susceptible plants
were the most affected, both showing a

severe reduction in plant height due to
the virus (only 35% to 36% of the height
of their control counterparts). The most
affected resistant variety was'Anastasia,
which reached 68% of the height of its
control,while the height of the other
resistant varieties ranged from 74% for
'Tyjoco'to 96% (not statistically signifi-
cant) for 3209,3205 and TY-199 (Table 1).
When the different varieties (resistant
and susceptible) were inoculated with
TYLCV at 28 DAS,all produced higher
yields compared to inoculation at 14 DAS.
The yield increase (or actually smaller
TYLCV-induced yield reduction) was
substantial, ranging from 50% forTY-199
and 3205,to 100% or more for 3193 and
'Tyjoco'(Table 1). In all cases, the plants
that were inoculated later were also taller.
However, regardless of the large increase
in yield,the symptom-severity score bare-
ly changed between plants inoculated
at 14 DAS and those inoculated 2 weeks
later (Table 1). A further substantial de-
crease in TYLCV-induced yield reduction
(a yield increase) was achieved by all the
tested varieties (resistant and susceptible
alike) following inoculation at 45 DAS.
The yield increase for the variety express-
ing the highest level ofTYLCV resistance,
TY-199,was from 2 kg/plant following in-
oculation at 14 DAS, 3.1 kg/plant follow-
ing inoculation at 28 DAS, to 4 kg/plant
following inoculation at 45 DAS (Table 1).
For varieties expressing a lower level of
TYLCV resistance, the yield increase was
even greater:'Tyjoco'yield, which was
1.1 kg/plant following inoculation at 14
DAS,more than doubled to 2.7 kg/plant
following inoculation at 28 DAS, and
reached 3.9 kg/plant following inocula-
tion at 45 DAS (Table 1). The susceptible
varieties showed a more marked increase
in yield due to the effect of plant age at
time of infection. R-1 3,which produced
0.01 kg/plant following inoculation at 14
DAS, reached 0.9 kg/plant following in-
oculation at 45 DAS-quite a substantial
increase. The same was true for 144-its
yield increased from 0.2 kg/plant follow-
ing inoculation at 14 DAS to 1.4 kg/plant
following inoculation at 45 DAS (Table 1).

In the present work, we examined wheth-
er plant age at time of inoculation has
any effect on the expression of genetic
resistance toTYLCV. Tomato plants were
inoculated at three different ages-14,28
and 45 DAS. We chose to inoculate at 14


DAS since this is the first true leaf stage-
in practice,the earliest stage for efficient
inoculation ofTYLCV. Inoculation at 28
DAS was selected to represent inoculation
just prior to transplant to the field-trans-
planting tomato plants 30 DAS is a com-
mon agricultural practice. Inoculation at
45 DAS was selected to represent inocula-
tion of plants following transplant to the
field, but not too long after transplant,
since in many whitefly-stricken areas,the
plants are infected shortly after exposure
to open-field conditions. At the two
earlier dates (14 and 28 DAS),inoculation
was performed in the greenhouse,while
at the later date of 45 DAS, the plants were
inoculated in the field.
Six different TYLCV-resistant tomato
varieties,as well as two susceptible
varieties,were tested. Plant age at time of
inoculation had no effect on the disease-
severity score of the susceptible varieties,
and a very small effect (if any) on the
disease-severity score of the resistant
varieties. In contrast, plant age at time of
inoculation had a significant effect on the
total yield of all of the varieties tested,
susceptible and resistant alike. However,
it should be noted that although inocula-
tion of older susceptible plants did result
in increased yield,the yield of the TYLCV-
infected susceptible plants was very low
for all of the ages tested.
The different resistant and suscep-
tible tomato varieties were tested for
TYLCV-induced yield reduction, which is
the ultimate test for viral (or any other
pathogen) resistance. The yield of each
infected entry was compared with that
of its control, uninfected counterpart.
All tested varieties suffered a significant
yield reduction due to inoculation with
TYLCV,at all three tested ages. The low-
est yield was produced by plants inocu-
lated at 14 DAS. The susceptible varieties
produced practically no yield following
inoculation at 14 DAS,whereas the yield
produced by the resistant varieties varied
according to their resistance level, rang-
ing between 18% and 45% of the yield
of their non-inoculated counterparts. A
smaller TYLCV-yield reduction-a sub-
stantial yield increase of between 50%
and 100%, depending on the resistance
level displayed by the tomato variety,was
achieved following inoculation at 28 DAS.
A further decrease in TYLCV-induced
yield reduction (yield increase of 30% to
40%) was achieved following inoculation
at 45 DAS. Moreover,the yield produced

byTYLCV-resistant tomato plants inocu-
lated at 45 DAS was from 100% to 300%
higher than that produced by plants
inoculated at 14 DAS (Table 1).
Like total yield, the number of fruits
produced by the inoculated plants
increased markedly following inoculation
at later age. Plant height was also affect-
ed by plant age at time of inoculation-
all tested varieties that were inoculated
at 28 DAS were taller than their counter-
parts inoculated at 14 DAS. This was not
necessarily the case for plants inoculated
at 45 DAS-four varieties reached the
same height,while two varieties showed
increases in this parameter. Interestingly,
the two varieties showing a statistically
significant effect of inoculation at 45 DAS
on plant height were those showing the
lowest level ofTYLCV resistance (Table 1).
In conclusion,the results from this
study clearly demonstrate the occurrence
of mature-plant resistance in tomato
plants that are susceptible and resistant
toTYLCV. However,while plant age at
time of inoculation had a strong effect on
yield, it barely affected the disease-sever-
ity score. This may indicate that older
plants are not necessarily more resistant
per se to TYLCV than younger plants, but
are merely able to dampen down the
devastating effect of the virus since they
are in an advanced developmental stage,
or are simply stronger than the younger
These results raise another ques-
tion-when is the"correct" or best
time to inoculate tomato plants when
screening for TYLCV resistance? This may
depend on the genetic material being
screened: if segregating populations are
being screened for individual resistant
plants, then it is best to inoculate at the
earliest possible stage, when the effect
of the viral infection is most severe. This
way the selected plants will indeed be
those showing the highest level ofTYLCV
resistance. If,on the other hand, com-
mercial varieties are being tested for level
of resistance, then inoculation at 28 DAS
may be most suitable as it represents
inoculation just prior to transplanting
to the field. Since most commercial to-
mato plants are sown in specialized and
protected nurseries,from an agricultural
point of view, 28 DAS may be the most
relevant stage for testing commercial

This work was supported in part by
USAID-MERC grant no. M21-037 to M.L.

Antignus Y, Nestel D, Cohen S, Lapidot M (2001)
Ultraviolet-deficient greenhouse environment affects
whitefly attraction and flight-behavior. Environ.

Cohen S, Harpaz (1964) Periodic rather than con-
tinual acquisition of a new tomato virus by its vector,
the tobacco whitefly (Bemisia tabaci Gennadius).
Entomol. Exp. andAppl. 7:155-166.

Friedmann M, Lapidot M, Cohen S, Pilowsky M (1998)
A novel source of resistance to tomato yellow leaf curl
virus exhibiting a symptomless reaction to viral infec-
tion.J. Am.Soc. Hortic.Sci. 123:1004-1007.

Garcia-Ruiz H, MurphyJF (2001) Age-related resis-
tance in bell pepper to Cucumber mosaic virus. Ann.
Appl.Biol. 139:307-317.

Lapidot M, Ben Joseph R, Cohen L, Machbash Z, Levy
D (2006) Development of a scale for evaluation of To-
mato yellow leaf curl virus-resistance level in tomato
plants. Phytopathology 96:1404-1408.

Lapidot M, Friedmann M (2002) Breeding for resis-
tance to whitefly-transmitted geminiviruses.Ann.
Appl.Biol. 140:109-127.

Lapidot M, Friedmann M, Lachman 0, YehezkelA,
Nahon S,Cohen S, Pilowsky M (1997) Comparison
of resistance level to tomato yellow leaf curl virus
among commercial cultivars and breeding lines.
Plant Dis.81:1425-1428.

Loebenstein G (1972) Localization and induced resis-
tance in virus-infected plants.Ann. Rev. Phytopathol.

Moriones E, Aramburu J, Riudavets J, Arno J, Lavina
A (1998) Effect of plant age at time of infection by
tomato spotted wilt tospovirus on theyield of field-
grown tomato. Eur.J Plant Pathol. 104:295-300.
Moriones E, Navas-CastilloJ (2000) Tomato yellow
leaf curl virus, an emerging virus complex causing
epidemics worldwide. Virus Res. 71:123-134.

Pico B, Diez M, Nuez F (1998) Evaluation of whitefly-
mediated inoculation techniques to screen Lycoper-
sicon esculentum and wild relatives for resistance to
Tomato yellow leaf curl virus. Euphytica 101:259-271.

Polston JE,Anderson PK(1997) The emergence of
whitefly-transmitted geminiviruses in tomato in the
western hemisphere. Plant Dis. 81:1358-1369.

Vidavsky F Leviatov S, Milo J, Rabinowitch HD, Kedar
N, Czosnek H (1998) Response of tolerant breeding
lines of tomato, Lycopersicon esculentum, originat-
ing from three differentsources (L.peruvianum, L.
pimpinellifolium and L. chilense) to early controlled
inoculation by tomato yellow leaf curl virus (TYLCV).
PlantBreeding 117:165-169.







J.W. Scott, S.F. Hutton, Y. Ji, and J.D. Edwards
University of Florida/IFAS, Gulf Coast Research and Education Center, Wimauma, jwsc@ufl.edu

Of the many tomato (Solanum lycoper-
sicum L.) breeding projects being covered
by the University of Florida,three of the
major priorities are to develop varieties
with resistance to Tomato Yellow Leaf Curl
Virus (TYLCV),tolerance to bacterial spot,
and improved fruit flavor and color. These
projects will be the major focus of this

The TYLCV resistance project started in
1990 and resistance genes have been
introgressed into tomato from the wild
tomato species S.chilense. Several breed-
ing lines have been released in the last
few years to provide seed companies with
germplasm for theirTYLCV resistance
breeding programs. With this material,
a line has to have two resistance genes
to attain a high level of resistance to
TYLCV and to other begomoviruses. It
has been difficult to attain lines with
the horticultural type desired because
some undesirable traits are linked to the
resistance genes (linkage drag). Also, it is
more difficult to incorporate more than
one resistance gene than a single gene.
Multiple disease resistant varieties have
resistance from single dominant genes.
Present TYLCV resistant varieties such as
'Tygress'/SecuriTY 28,and newer ones
have resistance conferred by a dominant
gene Ty-1 orTy-2. So far,these genes
have been effective in Florida but the
virus has overcome these resistances in
some areas of the world. IfTy-1 resistant
varieties were widely deployed in Florida
it is possible that virulent virus strains
would emerge that would render these
varieties susceptible. Thus, development
of improved germplasm with other genes
is necessary to provide long term, durable
resistance. These genes can be used alone
or in combination with existing genes
such asTy-1 orTy-2.

To facilitate the incorporation of our
resistance genes we have been working
intensively with molecular markers since
1996. If molecular markers tightly linked
to resistance genes can be identified,
resistance can be incorporated by marker
assisted selection (MAS). MAS would
accelerate the breeding process four-
fold:without markers we can make one
backcross every two years utilizing disease
inoculation and selection for resistance
in the field; with MAS,one can make four
crosses in two years without growing any
plants in the field. Developing markers
for MAS however has been expensive and
time consuming. The good news is that
there have been tremendous advance-
ments in marker technology and many
things are possible now that were not
available in 1996. So far,we have identi-
fied two resistance genes in our breed-
ing program. From accessions LA2779
and LA1932,theTy-3 gene is located on
chromosome 6 in a region near theTy-1
gene (Ji etal., 2007). More recently,from
some lines derived from LA1932,theTy-4
gene is located on chromosome 3 (Ji et
al.,2009). We have good markers for both
genes and tomato breeders can now use
MAS in their breeding programs forTy-3
and Ty-4. Thus, incorporation of these
genes into acceptable tomato varieties for
Florida will be greatly facilitated. Beyond
this, there are other resistance genes that
we have yet to locate; experiments are
presently underway to find these genes so
they too can be utilized in developing du-
rable resistant varieties. We are also using
molecular markers concentrated near the
Ty-3 gene to fine map the resistance gene
and reduce linkage drag.

Breeding for bacterial spot tolerance
(Xanthomonasspp.) has been a priority
in the breeding program since 1982 and
not a single tolerant variety has yet been

released. This has been discouraging for
the breeder and tomato growers in Florida
who are threatened by this disease which
is ubiquitous in Florida. The first breeding
problem has been that the pathogen has
evolved virulent races even in the absence
of tolerant varieties. There are at least four
races (T1,T2,T3,and T4) of the pathogen
and all butT2 have been prevalent in
Florida. Today, it appears that the major
race is T4 with T3 still present as well. We
need to develop varieties with tolerance
to both these races, and the tolerance
genes should not be race specific, so as to
help prevent the emergence of another
virulent race that overcomes the toler-
ance. Whereas past breeding efforts have
not resulted in an acceptable variety,
knowledge gained has put us in a position
to move forward more expediently. Sam
Hutton studied resistance to race T4 utiliz-
ing three breeding lines with resistance
genes from several accessions including
'Hawaii 7998,'our main sources of resis-
tance to race T1. Other resistance came
from PI 114490 and S. pimpinellifolium
accessions P1128216 and P1126932 (the
two latter accessions having resistance to
race T3). Resistance from each of the three
breeding lines was partial (hence the term
tolerance) and multigenically controlled
by additive, dominant,and epistatic gene
action (Hutton, 2008).
A major effort was also made to find
molecular markers linked to the toler-
ance genes. Markers representing several
chromosomal regions were identified as
being associated with tolerance. Follow-
up experiments were done in fall 2008 to
verify these associations of markers with
tolerance. From this work, markers on
chromosomes 11 and 3 were positively
associated with tolerance while markers
on chromosomes 12 and 7 were associ-
ated with susceptibility. The marker on
chromosome 7 was linked to the 1-3 gene
that confers resistance to fusarium wilt


(Fusarium oxysporum f.sp. lycopersici) race
3. This confirms observations that variet-
ies with fusarium wilt race 3 resistance
have been more susceptible to bacterial
spot than other varieties. We have been
backcrossing bacterial spot tolerance into
fusarium wilt race 3 resistant breeding
lines. In spring 2009,we found one of the
lines being developed did have a high lev-
el of bacterial spot tolerance and that our
markers on chromosomes 3 and 11 were
present in this line. From here we can
use MAS in future backcrossing and this
should greatly facilitate development of
fusarium wilt resistant lines with bacterial
spot tolerance. These markers will also be
used for MAS in other breeding lines. At
present,we are not sure how tightly linked
our markers are with the tolerance genes,
but we will learn more about that as we
proceed. It will be necessary to moni-
tor tolerance along with MAS to insure
the tolerance is not lost to some degree.
If possible, given funding constraints,
we hope to develop more markers to
identify tolerance genes. Useful molecular
markers have been limited in the genetic
material we have been working with, but
we are part of a national USDA project
called SolCap that is developing new
markers. This project should prove useful
in expanding our marker library,and quite
possibly, be of use in verifying the precise
location of bacterial spot tolerance genes.
In summary, breeding for bacterial spot
has been difficult, but we now have better
tools for making progress. In the mean-
time,we have been testing bacterial spot
tolerant hybrids and continue to be inter-
ested in Fla. 8555 which has performed
well in three yield trials so far. Otherwise,
some bacterial spot tolerance has been
evident within the bacterial wilt (Ralstonia
solanacearum) resistance program for rea-
sons we do not yet fully understand. An
inbred that looks interesting as a parent
in initial testing is Fla. 8626. This inbred
has huge fruit along with bacterial disease

Fla. 8153 was released in 2006 as'Tasti-
LeeTM' (Scott et al., 2008) and seed is
now available from Bejo Seeds. For seeds,
contact Greg Styers: G.styers@bejoseeds.
com, phone 805-689-1627. This variety
has been described at previous Tomato
Institutes and details will not be given
here. This crimson variety boasts about

25% more lycopene than the average
tomato variety, providing superior red
interior color. It has performed well in nu-
merous taste panels and was released as
a premium variety to be labeled for better
competition with greenhouse tomatoes in
the supermarket (where Florida tomatoes
have lost market share in recent years). To
ensure maturity and the desired quality
to compete,fruit should be picked at the
breaker stage. Test marketing is underway
this fall and results should be available
at nextyear'sTomato Institute. Growers
with produce stands and/or U-pick opera-
tions might try planting'Tasti-Lee'and see
if they get a positive response from their
customers. It has been a reliable yielder in
numerous trials and on grower farms with
fruit size being a little smaller overall than
varieties typically grown in Florida.
We have identified a fruity-floral flavor
note that is appealing,and we are back-
crossing it into the parents of'Tasti-Lee'
for further flavor improvement of this
hybrid. This flavor note has been difficult
to fix for good expression but one of the
lines in this procedure, Fla. 8629, has been
rated at the top of all four taste panels
where it has been tested. Furthermore,
hybrids heterozygous for Fla. 8629 have
also done well suggesting that'Tasti-Lee'
could be improved for flavor by improving
only one of the parents for the fruity floral
trait. Horticultural improvement is needed
as Fla.8629 needs greater fruit size and
firmness. If'Tasti-Lee'can find a market
niche, we hope to be able to follow it with
a fruity-floral version of the same variety.
Otherwise,emphasis on good flavor is
stressed in the whole breeding program.
One new inbred that has had good flavor
is Fla.8735. This line has large,firm fruit
with excellent locule formation,the latter
likely relating to the ability of this line
to carry a nice acid level (since acids are
more prevalent in locules than pericarp).
Numerous test crosses are being made
with Fla. 8735 to attain improved hybrids
for the Florida market.

This variety (Scott et al., 2009) was tested
as Fla.8363 and Gulf Stream but was
named'Tribeca'due to some trade mark
issues with the name Gulf Stream. Vilmo-
rin Inc. is the seed company producing
seed of this variety. Some germination
problems have delayed seed availability,
but this problem should be resolved by
switching the direction of the cross. Seed

will be available from Caroline Cordier:
Caroline.cordier@vilmorin.com, phone
520-940-1539.The main features of this
variety are that it is resistant to tomato
spotted wilt virus and it has heat-tolerant
fruit setting ability. The major produc-
tion region will be North Florida and the
southeast where tomato spotted wilt is
a problem and where'Tribeca'has done
well in several trials over multiple years.
On the peninsula of Florida, it is suggested
that growers try'Tribeca'in their early fall
plantings for its heat-tolerant setting abil-
ity as it has performed well under these
conditions. Seed should be plentiful for
next fall and JW Scott can be contacted to
obtain smaller seed samples for testing.*

Hutton, S.F. 2008. Inheritance and mapping of
resistance to bacterial spot race T4 (Xanthomonas
perforans) in tomato, and its relationship to race T3
hypersensitivity, and inheritance of race T3 hypersen-
sitivity from P1126932. (PhD dissertation, University

Ji, Y, D.J. Schuster, andJ.W. Scott. 2007. Ty-3, a bego-
movirus resistance locus near the tomato yellow leaf
curl virus resistance locus Ty-1 on chromosome 6 of
tomato. Molecular Breeding 20:271-284.

Ji, Y. J. W. Scott, DJ. Schuster, and D.P. Maxwell. Molecu-
lar mapping ofTy-4, a new tomato yellow leaf curl
virus resistance locus on chromosome 3 of tomato.J.
Amer.Soc.Hort.Sci., 134:281-288.

Scott,J.W., S.M. Olson, andJ.A. Bartz. 2009.'Tribeca'
hybrid tomato; Fla. 8124C and Fla. 8249 breeding
lines. HortScience 44:471-473.

Scott,J.W., EA. Baldwin, H.J. Klee, J.K. Brecht, S.M.
Olson,J.A. Bartz, and C.A. Sims. 2008. Fla. 8153 hybrid
tomato; Fla. 8059 and Fla. 7907 breeding lines. Hort-
Science 43:2228-2230.








J.W. Noling, University of Florida/IFAS, Citrus Research & Education Center, Lake Alfred, FL,jnoling@ufl.edu

Drip fumigation is defined simply as the
application of a soil fumigant through a
drip irrigation system. Some soil fumi-
gants, like Vapam (metam sodium) and
K-Pam (metam potassium),are read-
ily soluble in water and can be applied
directly into irrigation water,while others
require special emulsified concentrate (EC)
formulations for application (Table 1). For
example, chloropicrin and Telone (1,3-
dichloropropene or 1,3-D) are not highly
soluble in water and must be premixed
with special emulsifying agents to en-
hance solubility in water and to promote
the uniform suspension of the fumigant
in water before delivery into the irrigation
lines. Considerable research is currently un-
derway to optimize application technolo-
gies to improve performance consistency
with drip applied alternative fumigants.
In California and Florida,drip applied
chloropicrin EC or Inline (a mixture of
1,3-D and chloropicrin with a emulsiftying
agent) has provided satisfactory soil-borne
pest control and yields of a variety of crops
which were equivalent to that of in-row,
shank applied methyl bromide and chloro-
picrin. Currently, over 55% of the California
strawberry acreage is drip fumigated with
either chloropicrin EC or Inline.

Prior to EPA completion and release of
the Fumigant Re-registration Eligibility
Decisions (RED's) on June 3,2009, drip
fumigation was being proposed as an al-
ternative to chisel application to minimize
fumigant-excluded buffer zones, personal
protective equipment (PPE) and costly
worker certifications,as well as for in-field
monitoring requirements for use of chisel
applied fumigants. It was fortunate for
Florida agriculture that EPA did not ulti-
mately demand such exorbitant standards
and requirement within the fumigant
RED's. This is not to say that drip fumiga-
tion with the alternative fumigants should
not be considered to be an effective, eco-
nomical,and environmental and worker
safe approach to fumigant use compared
to that of standard shank injections. With
drip approaches, fewer, more fuel-efficient
tractor operations are expected to reduce
overall fumigant application and produc-
tion costs. Fewer workers in the field at
the time of application also translates
into a safer environment for workers with
reduced grower liabilities, and with some
fumigants it has the potential to signifi-
cantly reduce costs for PPE (boots, gloves,
coveralls, respirators, etc.) when needed.
Safe and effective drip fumigation re-

TABLE 1. Soil fumigant product dilutions (volume:volume) to achieve various parts per million
(ppm) concentrations in irrigation water'. To achieve 1000 ppm Chloropicrin EC in irrigation
water requires a mixture of 1 gallon Chloropicrin EC into 1507 gallons of irrigation water.
Fumigant Formulation Ib a.i./ gal Product Dilution in Water
(vol. product: vol. water)
500 ppm 1000 ppm 1500 ppm
Chloropicrin EC 94% chloropicrin 12.58 1: 3015 1: 1507 1: 1005
Pic-Clor 60 EC 56.7% chloropicrin 6.73 1: 1613 1: 807 1: 538
37.1% 1,3-D 4.49
Telone EC 93.6% 1,3-D 9.45 1: 2265 1:1133 1: 740
Telone Inline 60.8% 1,3-D 6.57 1:1575 1: 787 1: 540
33.3% chloropicrin 3.73
Vapam HL 42% metam sodium 4.26 1: 1021 1: 510 1: 340
Kpam HL 54% metam potassium 5.8 1: 1390 1: 695 1: 463
zConcentrations of chloropicrin or 1,3-D which exceed 1500 ppm may result in precipitation of the fumigant (when solubility
limits are exceeded -2000 mg/1) and to damage to PVC pipelines of the irrigation system. For this reason, irrigation lines must
be thoroughly flushed of fumigant to prevent damage. Due to product inconsistency and ineffectiveness, none of the above
fumigants should be applied below 500 ppm. Growers assume final responsibility for determining irrigation flow rates and for
achieving desired product concentration irrigation water.

quires an understanding of how different
physical, chemical and environmental fac-
tors affect water and gas phase movement
of the different soil fumigants. Addition-
ally, it requires new chemical injection
equipment with proper safety devices,
a leak-free drip-irrigation system with
uniform water distribution, and fumigant
application and dilution into the proper
amount of water. A brief discussion of
these factors follows.

Most of the soils of peninsular Florida
are Spodosols, defined as poorly drained
fine sands (96%-98% sand,<2% silt, clay,
and organic fractions) with an underlying
impermeable (spodic) horizon 18 to 24
inches below the soil surface. Above the
spodic layer soil water holding capacity
is low, typically in the range of 4% to 8%,
with water permeability of 6 to 20 inches
per hour. Water tables are shallow,and,in
many fields, water may pond or flood after
heavy rains,enforcing the need for a drain-
age system of ditches and canals. Water
movement in soil is principally vertical,
with very little lateral movement. Seep-
age and drip irrigation are the principal
means of irrigation used in the raised bed,
plasticulture system of Florida. The sandy
nature of our soils has constrained our
ability to move and uniformly distribute
a drip fumigant away from its point of

A significant amount of research has been
conducted to characterize the dynamics
of drip irrigation water movement and use
of the drip system for chemical delivery.
These studies have relied upon tracking
the movement and spatial distribution
of water soluble colored dye, introduced
into the irrigation stream. Movements of
water-borne dye and fumigant have been
investigated for varying injection periods
and total water volumes, drip tube num-


bers per bed,flow rates, emitter spacings,
soil compaction regimes,and bed dimen-
sions. The overall results of these studies,
as well as generalized summary of field
results of drip fumigation trials,form the
basis for the following recommendations
for maximizing water phase movement
of alternative fumigants,such asVapam,
K-Pam and chloropicrin ECand Inline. A
separate discussion of gas phase move-
ment will follow.
In general,the results of all of the previ-
ous dye studies have repeatedly shown
that the average width,depth,and cross-
sectional area of the wetted zone gener-
ally increases with irrigation water volume,
typically forming a hemispherical shape
until water fronts from adjacent emitters
along the drip tape collide. As these fronts
collide,a wetted strip of no more than
12 to 15 inches develops parallel to the
drip line. Measured laterally from the drip
emitter, outward water movement was
seldom measured more than 6 to 7 inches.
Depending on the width of the bed,these
studies demonstrated that it was virtually
impossible to wet more than 40% to 60%
of the raised plant bed with a single drip
tube. With two drip tapes, it was pos-
sible to wet from 75% to 95% of the bed.
In general,the wetting front is typically
two- to threefold greater with use of two
drip tubes rather than with a single tube
per bed. But even with two tapes per bed,
it is always more difficult to wet a high
proportion of a wide bed compared to a
narrow bed.
For a given water volume,the use of
two tapes per bed increased spatial distri-
bution of irrigation water simply because
of the spacing between drip tubes and
the increased number of emission points
along the bed. In the overall analysis of
the relationship between total irrigation
water volume and spatial distribution of
the wetted zone, it appears that most bed
wetting occurs in the time to deliver the
first 300 gallons of water per 100 linear
feet of row. If a maximum rooting depth
of 16-20 inches from the top of the bed
is assumed,then irrigation run times re-
quired to deliver water volumes of 100 to
200 gallons per 100 feet of row should not
be exceeded so as to contain the wetting
front within the future rooting zone of the

Upon drip delivery to soil,the fumigant
moves through the soil within a radially

advancing water front. Differences in
soil type can significantly affect water
flow which controls the solution-phase
transport of dissolved soil fumigants.
Faster movement and vertical drainage
of fumigant solutions occurs in our fine
sandy soils compared to other soils with
higher percentages of silts and clays. Soil
air spaces are also restored more quickly
in sandy soils which then promotes earlier
gas diffusion and rates of flow through
open air passages in soil. As water moves
downward in the soil,a corresponding
increase in the volume of soil air space
occurs. In order to restore the dynamic
equilibrium between water and gas phase
concentrations, more molecules of the
fumigant must therefore enter into the va-
por or gas phase. In general,field research
has demonstrated that fumigants move in
gas phase approximately 3 to 5 inches be-
yond the wetting front. Metam products
may only move only a few inches from
the wetted front; whereas, Inline may
move as much as 6 to 8 inches beyond the
wetted zone due to the stronger vapor
pressure of 1,3-D and chloropicrin.
In general,fumigant concentrations
decrease with time after application and
with distance from the drip tapes emit-
ters (Fig. 1). Lowest measured fumigant
concentrations and highest pest survi-
vorship are generally observed at the
bed shoulders, particularly with wide
beds. Higher rates of fumigant applica-
tion which require more water to apply,
in many circumstances are needed to
laterally move the fumigant wetting front
at lethal concentration to the shoulders
of the bed. In many Georgia and Florida
studies on fine sandy soils,the rapid drain-
age and poor lateral movement of Inline
(25-30 gal/acre),Vapam (75 gal/acre) or
K-Pam (60 gal/acre) have resulted in poor
nutsedge control on bed shoulders when
a single drip tape was used. Even with
two tapes per bed, some drip-applied fu-
migants with low vapor pressure and low
diffusivity have failed to control nutsedge
on the bed shoulders or even in areas
between the dual tapes. Nematodes are
usually much easier to kill than nutsedge
and effective control is often observed at
the bed shoulders.
In general, reduced effectiveness and
consistency can be observed with any
fumigant product when applied through a
single drip tape per bed. Increasing rates
of applications have helped to overcome
this problem, but oftentimes not entirely.

Previous research has also demonstrated
that fumigant concentrations (and their
efficacy) could be enhanced across the
bed by using highly retentive mulches,
such as virtually impermeable films (VIF)
or metalized mulches. Fumigant reten-
tion under these mulches are prolonged
at higher concentrations which results in
higher overall exposure to lethal concen-
trations and improve lateral spread of the
fumigant across the bed.

After a fumigant is applied to soil as a
liquid, it then converts into a gas,once
open air passages in the soil redevelop. As
indicated previously,fumigant movement
in soil begins in the water phase,advanc-
ing within the water front, and then after
irrigation is stopped and gravitational
water moves downward to restore soil
air spaces,through gas phase diffusion.
To achieve satisfactory pest control,the
fumigant must remain in contact with
the target pest for sufficient time to kill
the organism. The pesticidal effect of
the fumigant on the target organism is
thus a function of both fumigant con-
centration (C) and time (T). That is to say
that the level of pest control achieved is
related primarily to pesticide concentra-
tion, outward radial movement of both
water and gas phase fumigant,which
determines total treated soil volume,and
residence time of the chemical in the soil.
Unfortunately, lethal concentrations ex-
pressed as fumigant concentrations over
time have not been developed, primarily
due to the high cost and sophistication
required to monitor gas concentrations in
soil,at diverse depths and bed locations.
There also are many different soil factors
and conditions capable of influencing
C xT values, so it may not be possible to
measure their separate influences on pest
control efficacy. In Florida's sandy soils,
Inline is usually applied at rates between
20 and 30 gal/acre,Telone EC at 10 to 12
gal/acre,Vapam at 30 to 35 gal/acre,and
K-pam 25 to 30 gal/acre. Typical dilution
rates result in fumigant concentrations of
500 to 1500 ppm.

Based on grower demonstration trials,
soils and grower production practices dif-
fer markedly,and the resulting differences
in soil type, compaction and depth of re-
strictive layers, can affect water movement
and the final distribution of chemicals



FIGURE 1.Cross-section of a raised plant bed illustrating the results of a grower field chemiga-
tion trial using a Water soluble dye to map the resultant water front.The results illustrate the
principally vertical and very limited lateral spreading of a water front throughout a raised plant
bed as the irrigation run time (volume) is increased from 2 to 6 hours.The results demonstrate
the potential difficulties in achieving pest control efficacy with a chemigated pesticide when less
than 50% of the bed is wetted during a 6 hour injection period.

10 bed bed | >ed

"Inches 5
Ground \ *
Below" -5 Treated
^ Zone

-15 I I
2 hour injection 4 hour injection 6 hour injection
On the Emitter

in soil. This was clearly demonstrated in
some grower trials where only very limited
lateral spreading of the water front oc-
curred as irrigation run time (volume) was
increased from 2 to 6 hours (Fig. 1). Given
the soil characteristics at these sites, it be-
comes apparent that the drip system can-
not be effectively and universally used for
delivery of alternative fumigants, at least
through a single drip tube. To determine
the suitability of any field site, growers
are encouraged to conduct their own dye
studies to optimize the utility of the drip
system for their own purposes. Growers
also should be reminded of the possible
effects of applying such large volumes
of water on bed architecture, leaching
of preplant fertilizers and plant nutrition
and health. Surely, some adjustments in
the fertility program, such as exclusive
reliance on postplant fertigation, must be
developed to minimize nutrient leaching
impacts from use of the drip system for
preplant soil fumigation.
Even though our knowledge and
understanding of the dynamics of drip
water movement in soil increases, it does
not mean that growers,armed with this in-
formation,will achieve immediate success
without cost or change. For example, it
was shown that flaws in irrigation system
design could significantly compromise
treatment efficacy of chemigating com-
pounds such asTelone ECorVapam. The
principal problem involved lack of delivery
uniformity throughout the entire field.
In one field trial,significant drops in drip
line water pressure from one end of the

field to the other, established a gradient of
diminishing volume of water output and
hence of treated soil volume. The results
of this dye trial clearly demonstrated
that use of pressure regulators across
the entire field with adequate water flow
sizing requirements is a must to insure
distribution uniformity. In this regard,the
irrigation system should be designed to
maintain a minimum line pressure of 8
to 10 psi along the entire drip line within
each row to assure uniform delivery of
fumigant product.
The proximity of the plant to the drip
tube has also been demonstrated to
be very important in terms of defining
pest control efficacy and plant growth
response with a drip fumigant. In separate
experiments, it was observed that Vapam
application rates as low as 10-15 gal/acre
could be effectively used for both tomato
and pepper crop destruction purposes, if
established plants were within two inches
of individual drip emitters. Identical stud-
ies with plants positioned 6 to 8 inches
from the drip line required a rate of 20-30
gal/acre and a longer irrigation run to
achieve the same level of plant mortality.
Presumably,a two-fold increase in ap-
plication rate was needed to compensate
for the additional distance required to
contact the primary root zone of the plant.
The problem is even further amplified
when one considers typical production
practice of laying the drip tape on one
side of the bed and planting the crop on
the bed center. On a wide bed (36 inches),
the bed shoulder opposite that of the

drip tape is typically untreated. Ideally
the tape would be placed in the center
of the bed and the crop planted offset of
the tape. Growers also should consider
a change in bed width since narrower
beds could be covered more uniformly
than wider 32-36 inch-wide beds. Given
the sandy nature of Florida soils, narrower
beds, drip tubes with closer drip emitter
spacing (likely in the range of 8-12 inches),
and planting practices which place plants
closer to the drip tube may need to be
adopted to more effectively utilize the
drip tape for application of alternative
fumigants. Unless two tubes per bed are
installed,drip fumigation may be better
suited for crop destruction and pest con-
trol protection of the double crop rather
than as relying upon it as the preplant
fumigant treatment of the primary crop.

Before considering drip fumigation as a
pest management tool,an evaluation of
irrigation system design and distribution
uniformity should be conducted to ensure
even water distribution and operating
pressure uniformity,and thus drip emit-
ter discharge rates within the field and
entire length of row. Any inconsistency in
drip flow will be reflected in variability in
fumigation rates, pest control efficacy,and
crop yield response. Other drip fumigation
considerations include:
* Placard the Field and ensure that the
irrigation system has functional back flow
prevention (required by law).
* Soil Preparation: Properly till the soil and
ensure adequate moisture to construct a
firm, com pressed, raised bed. For seepage-
irrigated fields, some adjustment in water
table after bed formation may be needed
to allow application of additional water.
* Avoid wet soils since the performance
of fumigants are negatively impacted by
excessive soil moisture.
* In fields without seepage irrigation,
consider deep tillage to destroy compact-
ed traffic pan layers to insure fumigant
penetration (both liquid and gas phase)
to depths directly below the raised bed.
In seepage fields,a deep tillage practice
could damage the spodic layer with re-
sultant loss in the ability to perch a water
* Install the drip tape(s) to a depth of 1-2
inches to avoid tape movement (verti-
cal or horizontal) along the row. Drip
tapes subject to heating and cooling
are capable of considerable movement


unless buried to a soil depth of at least
1 inch. Spread the tapes as far apart as
possible to ensure wetting of the bed
center and shoulders. In general, research
has demonstrated that fumigants move
in gas phase 3 to 5 inches beyond the
wetting front. On beds wider than 36
inches, it may not be possible to distribute
fumigant to the bed shoulders even with
2 tapes spaced 12 to 15 inches apart.
* Since pump capacity with irrigation
zones is frequently limiting, two low-flow
drip tapes (0.2 to 0.25 gpm / 100 row feet)
should be used to match previous flows
used for the single drip tape. Use of drip
tape(s) for end of season crop termination
or double cropping treatment requires

proper filtration and tape cleaning pro-
* Install a high barrier/VIF mulch to re-
duce field emissions and to enhance cross
bed diffusion of fumigant gases and pest
control efficacy, particularly of weeds,at
reduced rates of fumigant use.
* Maintain adequate soil moisture prior to
and after application to maintain bio-
logical activity in soil and susceptibility to
fumigant treatment.
* After installation of the drip tape and
plastic mulch, pressurize the irrigation
system and inspect the system for leaks
within irrigation lines, manifold connec-
tions,end drains,or damaged drip tape
within rows causing puddling in the row

middles. Repeat the irrigation process to
avoid problems from developing at the
time of fumigant injection.
* Repeated operation of the irrigation sys-
tem prior to drip fumigation will help to
ensure uniformity of chemical application
across the treated area.
*To ensure water (and fumigant) distribu-
tion uniformity throughout the field and
within individual rows, pressure variation
within the drip tape should be minimized.
Poor pressure and flow uniformity is
generally caused by pressure and flow
variability in drip tape emitters through-
out the field.*






Patrice G. Champoiseau1, Jeffrey B. Jones1, Caitilyn Allen2, and Timur M. Momol
SUniversity of Florida/IFAS, Dept. of Plant Pathology, Gainesville, FL,jbjones@ufl.edu
2 University of Wisconsin-Madison, Dept. of Plant Pathology, Madison, WI
3 University of Florida, District Extension Director, Gainesville, FL

Bacterial wilt caused by Ralstonia sola-
nacearum is one of the major diseases
of tomato and other solanaceous plants
worldwide. Bacterial wilt in commercial
tomato fields may result in significant yield
reductions and even complete losses under
favorable disease conditions (Boshou,2005).
The disease generally occurs in lowlands in
tropical and subtropical areas. In the United
States, R. solanacearum phylotype II (race
1 biovar 1) occurs naturally and causes
bacterial wilt in states south of Maryland,
including Florida (McCarter, 1991).
One subgroup of R.solanacearum desig-
nated race 3 biovar 2 (R3b2) attacks plants at
higher altitudes in tropical, subtropical,and
warm-temperate areas. Initially described as
pathogenic on potato and tomato, R3b2 can
also wilt eggplant, pepper,and geranium
(where it causes Southern wilt disease).
Other solanaceous and non-solanaceous
plants also may act as alternative hosts for
R3b2 (Lemay et al., 2003). This pathogen is
extremely destructive; on potato alone, R3b2

is responsible for an estimated $1 billion
US in losses each year on the global scale
Because of its host range, worldwide
distribution,and aggressiveness, R3b2 is
considered a serious threat to agriculture
production in the US and Canada,where it
is not known to be established. In order to
prevent its introduction and establishment
in the US, R3b2 was listed in 2002 as a"Select
Agent plant pathogen"and is subject to the
strictest biosecurity regulations (Lambert,
2002). R3b2 has been accidentally intro-
duced into the US several times on imported
and infected geranium cuttings, resulting in
millions of dollars in losses due to regulatory
eradication protocols (Kim et al.,2003;Wil-
liamson et al.,2002).
Along with a description of the disease
and causal organism,we will discuss below
diagnostic methods and strategies for best
management of bacterial wilt of tomato and
control of R.solanacearum, with emphasis
on R3b2.These strategies include exclusion-

ary practices to prevent introduction of the
pathogen to disease-free locations and pre-
vent spread from infested to healthy fields,
as well as effective field sanitary cultural
practices for locations where the pathogen
is known to be established.

Symptoms. Symptoms induced by R3b2
cannot be distinguished from wilt symp-
toms caused by other R. solanacearum
strains. The first visible symptom is wilting
of the youngest leaves during the hottest
part of the day, often on just one side of a
leaflet or on a single branch. At this stage,
plants may appear to recover at night when
temperatures are cooler. Under favorable
conditions,the entire plant may wilt quickly,
leading to general wilting and yellowing of
foliage and eventually plant death. Another
common symptom associated with bacte-
rial wilt in the field is plant stunting. This
symptom may appear at any stage of plant
growth;sometimes, infected tomato plants



will not show symptoms until just before
fruit ripening,when they undergo rapid col-
lapse. A longitudinal slice of infected stems
will reveal vascular browning,visible as long,
narrow,dark-brown streaks. In succulent
young plants of highly susceptible varieties,
the stem can collapse,and grey-white bacte-
rial ooze may be visible on stem surfaces
(McCarter, 1991).
Symptom expression is favored by high
temperatures (85-95F). Under cool tem-
peratures or when tolerant or moderately
tolerant tomato cultivars are grown, plants
may remain latently infected (symptom-
less) for extended periods of time. Latent
infections are of major importance in the
epidemiology of the disease as the absence
of visible symptoms makes detection of R.
solanacearum very difficult.
Cycle and epidemiology. R. solanacearum is
primarily a soilborne and waterborne patho-
gen. No aerial spread of the pathogen has
been reported so far. It primarily infects host
plants through their roots, entering through
wounds formed by lateral root emergence
or by root damage caused by soilborne or-
ganisms (e.g.,the root-knot nematode). The
bacterium can also enter plants by way of
stem injuries from insects, handling, or tools.
Once inside the roots or stems,the bacte-
rium colonizes the plant through the xylem
in the vascular bundles (Denny,2006).
R3b2 is most severe on plants between
75 and 95F and decreases in aggressive-
ness when temperatures exceed 95C or
fall below 60F. Active disease at tem-
peratures below 60F is rare (Ciampi and
Sequeira, 1980; Hayward, 1991).
The pathogen can be spread from in-
fested to healthy fields by soil transfer on
machinery and surface runoff water after
irrigation or rainfall. It also can be dis-
seminated from infested ponds or rivers
to healthy fields by flooding or irrigation.
Plant-to-plant infection can occur when
bacteria shed from infected roots move to
roots of nearby healthy plants. Long-dis-
tance spread of the pathogen can occur
with transportation of latently infected
transplants (McCarter, 1991).
The bacterium can survive for days and
up to years in infested water,wet soils or
deep soil layers (> 30 inches),from where it
can be dispersed. Diverse biological (such as
antagonist microorganisms) and environ-
mental factors (mainly temperature,soil
type and moisture) can affect survival of R.
solanacearum in soil and aquatic habitats
In natural habitats, R3b2 can survive mod-
erate winters in plant debris in soil,in weed

TABLE 1. Characteristics of races and their relationship to biovars of Ralstonia solanacearum (from
Denny and Hayward,2001; Daughtrey,2003).
Race Primary hosts Geographical distribution Biovar
1 Wide (tobacco, tomato, solanceous Asia, Australia, 3, 4
and nonsolanaceous weeds, diploid Americas 1
bananas, groundnut, potato, pepper,
eggplant, olive, ginger, straw-
berry, geranium, Eucalyptus, other
2 Triploid bananas, other Musa spp. Caribbean, Brazil, Philippines 1
3 Potato and tomato Worldwide except US and 2 (or 2A)z
4 Ginger Australia, China, Hawaii, India, 4
Japan, Mauritius, South Asia
Unknown India 3
5 Mulberry tree China 5
z Typical race 3 strains are sometimes referred to as biovar 2A. New race 3 strains from the Amazon basin have been placed in
a new biovar, designed as 2T or N2 (their relation to races is unclear).
TABLE 2. Hosts of Ralstoniasolanacearum race 3 biovar 2 (from Floyd, 2008; Lemay,2003).
Primary hosts Lycopersicon esculentum (tomato)
Solanum tuberosum (potato)
Other cultivated hosts Beta vulgaris (beet)
Capsicum spp. (peppers)
Momoridica charantia (bittergourd)
Pelargonium spp. (geraniums)
Phaseolus vulgaris (bean)
Solanum melongena (eggplant)
Weed hosts Brassica spp. (mustards),
Cerastium glomeratum (sticky chickweed)
Chenopodium album (lambsquarters)
Datura stramonium (Jimson weed)
Drymaria cordata (whitesnow)
Melampodium perfoliatum perfoliatee blackfoot)
Polygonum capitatum (pinkhead smartweed)
Portulaca oleracea (purslane)
Solanum carolinense (horsenettle)
Solanum dulcamara (bittersweet or climbing nightshade)
Solanum nigrum (black nightshade)
Stellaria media (common chickweed)
Tropaeolum majus (garden nasturtium)
Urtica dioica (stinging nettle)

hosts or in the rhizosphere of non-host
plants,which act as inoculum reservoirs.
Infected semi-aquatic weeds,such as Sola-
num dulcamara (bittersweet nightshade,
also known as climbing or woody night-
shade) can release large populations of the
bacterium from roots into river water when
temperatures start to increase after winter.

A"species complex" Ralstonia sola-
nacearum (Smith 1986;Yabuuchi et al., 1996;
formerly called Pseudomonas solanacearum)
is considered a"species complex,"due
to significant variation within the group
(Fegan and Prior,2005). Itwas historically
subdivided into five races, based loosely on
host range,and five biovars, based on the
different ability of R. solanacearum strains to
produce acid from a panel of 5 to 8 carbo-
hydrate substrates, including disaccharides
and sugaralcohols (Table 1).There are no
laboratory tests to define the"race"of an iso-
late because host ranges of strains are broad
and often overlap. Recently,a phylogeneti-
cally meaningful classification scheme was
developed based on DNA sequence analysis

(Prior and Fegan,2005).This scheme divides
the species complex into four major groups
called phylotypes that broadly reflect the
ancestral relationships and geographical
origins of the strains.
R.solanacearum R3b2 strains belong
to phylotype II and sequevars 1 and 2
(Fegan and Prior,2005). The R3b2 strains
distributed outside South America belong
to sequevar 1.
Culture, identification and conserva-
tion. R. solanacearum is a Gram-negative,
rod-shaped, largely aerobic bacterium that
is 0.5-0.7 x 1.5-2.0 pm2 in size. Liquid and
solid (agar) growth media are commonly
used for culturing the bacterium. For most
strains,the optimal growth temperature is
between 82 and 90F (Denny and Hayward,
2001; Hayward, 1991). R3b2 strains have a
lower optimal growth temperature of 80.5oF.
On solid agar media,individual bacterial
colonies are usually visible after 36 to 48
hours of growth at 82oF,and colonies of the
normal or virulent type are white or cream-
colored, irregularly shaped, highly fluidal,
and opaque. Occasionally, colonies of the
mutant or non-virulent type appear; these


TABLE 3. USDA-APHIS validated test kids for
Ralstonia solanacearum (from Floyd,2007).

Rs Immunostrip Test
Agdia Inc.
30380 County Road 6
Elkhart, IN 46514
Website: http://www.agdia.com
Phone: 800-622-4342
Potato Brown Rot Pocket '"Diagnostic
Central Science Laboratory (CSL)
Sand Hutton, York, Y041 1 LZ
Website: http://www.csl.gov.uk
Phone: 44 1904 462600
Ralstonia solanacearum SPOTCHECK LF'"
Adgen, Ltd.
Nellie's Gate, AYR
Scotland, KA6 5AW
Website: http://www.agden.co.uk
Phone: 44 1292 525275

are uniformly round,smaller,and butyr-
ous (or dry). A tetrazolium chloride (TZC)
medium (Kelman,1999) can differentiate the
two colony types. On this medium,virulent
colonies appear white with pink centers and
non-virulent colonies are a uniform dark red.
R. solanacearum can be stored for many
years at room temperature in sterilized
tap,distilled or deionized water. Itwill also
survive long-term at-80C in liquid culture
broth containing 40% glycerol (Denny and
Hosts. R. solanacearum race 3 biovar 2 has
a smaller host range than race 1 (Denny,
2006).Although primary hosts of the
pathogen are potato and tomato, R3b2 also
was shown to induce symptoms on egg-
plant,geranium,and pepper. Some other
solanaceous and non-solanaceous plants
can be hosts of R3b2 (Table 2).
Sign. Bacterial streaming is a common
sign of R.solanacearum (McCarter, 1991).
When cut stem sections from infected
plants are placed in water,threads of
a viscous white slime can be observed
streaming from the cut end of the stem
within minutes. These threads are bacterial
ooze exuding from the infected xylem
vascular bundles. This streaming test is a
valuable diagnostic tool for quick detection
of bacterial wilt diseases in the field. How-
ever it may not be useful early in disease
Detection and identification. The first step
in pathogen identification consists of obser-
vation of sign and disease symptoms. Symp-
tomatic plants in the field or in the green-
house can be tested for R.solanacearum
using screening tests that can facilitate early
detection of the pathogen.These screening
tests include bacterial streaming, plating on
a semi-selective medium such as modified
SMSA (Elphinstone, 1996),and immuno-
diagnostic assays using species-specific
antibodies. The USDA-APHIS-PPQ has tested

and recommends the use of commercially
available immunostrips for rapid detection
of R.solanacearum in the field or lab (Table
3).Screening tests are inexpensive, fast and
require minimum equipment. However,
they cannot be used to identify the"race"or
Several microbiological and molecular
methods can be used to identify R.sola-
nacearum at the sequevar, race and biovar
level,following recovery from asymptom-
atic plants, or from water or soil samples.
These methods include immunodiagnostic
assays using species-specific antibodies,
polymerase chain reaction (PCR) with spe-
cies-specific primers,and biovar test (Denny,
The biovar test,a bacteriological as-
say based on the differential ability of R.
solanacearum strains to produce acid from
a panel of disaccharides and sugar alco-
hols,requires specialized media and takes
several weeks (Denny and Hayward,2001).
Unequivocal identification of R3b2 must rely
on at least two distinct methods, including
the biovar test and one of the DNA-based
tests that use PCR to amplify an R3b2-specif-
ic DNA fragment. Because of current United
States regulations,the only laboratory
legally permitted to conclusively identify
R3b2 is the USDA-APHIS-PPQ National Plant
Germplasm and Biotechnology Labora-
tory in Beltsville,MD. A diagnostician who
identifies R.solanacearum in samples from
tomato, potato or geranium should consider
the possibility thatthe strain may be R3b2
and immediately contact the APHIS-PPQ lab
in Beltsville.
USDA-APHIS-PPQ-National Plant
Germplasm and Biotechnology Laboratory
Powder Mill Road Beltsville,MD 20705
301-504-7100 Fax: 301-504-8539

Because R.solanacearum is a soilborne
pathogen and host resistance is limited,
bacterial wilt is very difficult to control
(Hayward, 1991; Saddler,2005). Moreover, R.
solanacearum is widely distributed and has
an unusually broad host range (Denny 2006;
Hayward, 1991). Thus, no single strategy
has shown 100% efficiency in control of the
In locations where the pathogen is pres-
ent or established. In locations where R.
solanacearum is established, some level of
bacterial wilt control is possible by using a
combination of diverse control methods.
These methods should be used as part of an

FIGURE 1. Effect of the integrated applica-
tion of Actigard (acibenzolar-S-methyl) and
Thymol on bacterial wilt of tomato after ar-
tificial inoculation of three tomato cultivars
in a field experiment (2006) in North Florida
100 Control
S90 Thymol
80 U Thymol + Actigard
C. 70
C 60
= 50 _______ _______ ______
S40 _______ ______ ______
( 30
0 1
Phoenix FL7514 BHN669
Tomato cultivars

integrated management strategy for most
effective control of the disease,and include:
Host resistance. Some level of bacterial
wilt control is possible using resistant or
moderately resistant tomato cultivars,
such as'FL7514'and'BHN 466' Resistance
in these cultivars may vary with location
and temperature, because of strain dif-
ferences (Hanson et al., 1996;Wang et al.,
Grafting susceptible tomato cultivars
onto resistant tomato or other solana-
ceous rootstocks is effective against Asian
strains of R.solanacearum and is used on
the commercial scale in different locations
worldwide (Saddler, 2005). Effectiveness of
grafting for use against R3b2 has not been
tested yet. Additionally, some reports sug-
gest that bacterial wilt-resistant tomato
cultivars and breeding lines may have
poor resistance to R3b2 (P. Prior, personal
Chemical control and soil treatment.
Chemical control by soil fumigation or
application of phosphorous acid has been
reported to be effective for controlling
bacterial wilt of tomato in the field (Chellemi
et al.,1994;Ji et al.,2007). Similarly, soil treat-
ments,such as modification of soil pH,heat
treatment by solarization,and the applica-
tion of stable bleaching powder have been
shown to reduce bacterial populations and
disease severity on a small scale (Saddler,
Drawbacks of these methods may
include environmental damage,cost,
and high labor input. Additionally, most
of these methods still have to be tested
against R3b2 strains of R. solanacearum.
When used,chemical control should be
integrated with other methods to reduce
selection pressure for pathogen resistance.
Recently, the use ofThymol,a plant-



TABLE 4. Recommended management strate-
gies for bacterial wilt on tomato caused by
Ralstonia solanacearum (from Momol, 2005).
Before Consider an effective weed control
planting program for use in and around tomato
fields and for aquatic weed control
around irrigation ponds.
Apply 3-4 years rotation and cover
crops for infested fields to reduce R.
solanacearum, weeds and nematodes.
Do not irrigate rotation and cover
crops with R. solanacearum contami-
nated pond or surface water, avoid
Use well drained and leveled fields
and do not use low-lying areas of the
Raise soil pH to 7.5-7.6 and increase
available calcium limingg).
Consider using infested fields (after
3-4 years rotation) during cooler
months for tomato production (i.e.,
spring season for north Florida).
During Exclude the pathogen by applying
production strict sanitation practices (pathogen-
free irrigation water, transplants,
stakes, machinery, etc.).
Chlorinate irrigation water continu-
ously when surface water or R. sola-
nacearum infested pond water is used.
Continue an effective weed control in
and around tomato fields and irrigation
Irrigate based on water need, avoid
over irrigation.
Apply plant resistance inducer, such
as Actigard (Syngenta) if you are using
moderately resistant cultivars (i.e., FL
7514). Actigard enhances resistance
against this disease if it is used in
combination with moderately resistant
After Exclude the pathogen by applying
harvest strict sanitation practices (pathogen
free irrigation water, transplants,
stakes, machinery, etc.).
Chlorinate your irrigation water
continuously if you are using surface
water or R. solanacearum infested
pond water.
Continue an effective weed control in
and around tomato fields and irrigation
Irrigate based on water need, avoid
over irrigation.
derived volatile biochemical (currently
not commercially available),was shown
to reduce disease incidence and increase
yield in field experiments in Florida (Ji et al.,
2005). Similarly,the application of the plant
resistance inducer,acibenzolar-S-methyl
(Actigard,Syngenta),in combination with
moderately resistant cultivars,was shown to
enhance resistance against bacterial wilt of
tomato in the field (Anith et al.,2004; Prad-
hanang et al.,2005). In a 2006 field experi-
ment in Quincy,FL, integrated application of
Thymol and Actigard showed significant re-
duction in the percentage of wilted tomato
plants,on cultivars that showed susceptibil-
ity to the disease after artificial inoculation
with the pathogen (TM. Momol, personal
communication; Fig. 1).
Biological control. Biological control based
on suppressive soils or known R.sola-
nacearum antagonists has shown promising
results in small scale experiments, but still
needs to be validated on a larger scale and

FIGURE 2. Regulatory procedure pathway for identification of Ralstonia solanacearum race 3
biovar 2 in the United States (from Floyd, 2008).

Detection surveys for greenhouse, Field crop diagnostic
nursery or field area Field crop diagnositc
Regulatory officials First dectores, diagnosticians
Regulatory officials

SSubmission of plant-exhibiting wilt symptoms
Intrastate or interstate transfer
-C -------------------------- -------
S Approved diagnostic screening laboratories (PPQ permit)
Must notify at sample reception a r ----------- r-------- --------.
State plant regulatory official, or --Sfa I Cooperative I NPDN Private
State plant health director and .......... I nu r1v I I netw rk a I uthnrzed I
-PPQregional office n authomedo .
S- Sanmple destruction
S R. solanacearum positive sample within 7 days in presence
-- -R -s p i -i -m - ofa PPQ representative
-- - -'- -[o
Identification of the i USDA-APHIS-PPQ-National Plant Germplasm
-race 3 blovar 2 and Biotechnology Laboratory
Beltsville, MD
T I t
Must Inform a representative of ( R. solanacearum race 3 biovar 2
HIS-Select Agent program positive identification

against R3b2 (Saddler,2005).
Phytosanitation and cultural practices.
The best strategy for controlling bacterial
wilt in the field consists primarily of phyto-
sanitation and cultural practices. In regions
where bacterial wilt of potato is endemic or
in locations where R.solanacearum is pres-
ent but not yet established, these methods
may be effective. These practices include
crop rotation with non-host plants such as
grasses, intercropping, control of weed and
root-knot nematode populations, planting
at non-infested production sites, removal
of weeds or crop residue where inoculum
persists, selection of appropriate planting
time to avoid heat, deep plowing of crop
residues,satisfactory soil drainage,and early-
and late-season irrigation management
(Hayward,1991; Saddler,2005). Recommen-
dations for best management of bacterial
wilt of tomato are listed in Table 4.
In locations where the pathogen is not
present. In US tomato-producing states, it
is important to prevent introduction and, if
inadvertently introduced,subsequent move-
ment of race 1 of R.solanacearum from in-
fested to healthy locations or fields. Effective
cultural sanitation practices are critical to
keep non-infested areas clean. Sanitation ef-
forts include planting only certified disease-
free plantlets,disinfesting all equipment
before moving it between fields, controlling
floodwater flow,and never using surface wa-
terfor irrigation. Atthe greenhouse, sanitary
practices for tomato transplant production
may include avoidance of sub-irrigation,
wide separation of greenhouses from field
production areas, disinfestation of all frames,
trays and tools,use of pathogen-free soils or

potting mix, control of weeds,and limited
handling of plants (Mc Carter, 1991)
Because of its status as a Select Agent,
government regulations in the US include
zero tolerance for R3b2. This zero toler-
ance includes reinforcement of quarantine
regulations, exclusionary practices, sanitary
protocols,and inspections designed to
prevent introduction of infected geranium
cuttings produced off-shore. A"New pest
response guidelines for R.solanacearum race
3 biovar 2"(Floyd, 2008) presents current
information for detection, control, contain-
ment,and eradication of this pathogen in
compliance with regulations. APHIS-PPQ
(2005) also developed "Minimum sanitation
protocols for offshore geranium cutting
production"for use by off-shore geranium
suppliers. It mandates implementation of
sanitation procedures to prevent accidental
introduction of R3b2 and to ensure that, if it
is introduced,the pathogen does not spread
within greenhouses, or on equipment or
In addition to establishing exclusionary
strategies, growers should monitor poten-
tially infested sites for early detection and
subsequent eradication of R3b2. Key sites
for monitoring include soils in which R3b2-
infected plants have been identified, rivers
and other surface water used for irrigation,
particularly when infected weed hosts may
be presentand tomato production fields
in the vicinity of geranium production
Regulatory response to detection of R3b2
in the US. Confirmed infestations of tomato
(or other solanaceous crops) by R3b2 will
require quarantine of fields,tomato trans-


plants,seedlings,or other plant material
associated with infested lots, including
processing facilities,storage bins, means of
conveyance,soil,and irrigation water. Host
removal and destruction is required along
with disinfestation,as well as several years
of non-host production in infested fields or
associated growing areas before the quar-
antine can be removed. In case of contami-
nation of water by the pathogen, irrigation
with surface water should be prohibited,
and water treatments, such as filtration or
chemical disinfection, may be applied under
control of legal authorities. Any permission
to irrigate would be subject to results from
sampling and testing water samples.
According to government regulations,
any positive detection of R. solanacearum
from a diagnostic screening laboratory
following detection survey by a regulatory
official should be sent to the USDA-APHIS-
PPQ NPGB Laboratory in Beltsville for identi-
fication of the race and biovar (Floyd,2008).
Upon receiving the sample,a state plant
regulatory official (or a state plant health in-
spector) and the PPQ regional office should
be notified as requested (Fig.2).

R3b2 is an important crop pathogen in both
developing and industrialized countries, re-
sponsible for millions of dollars losses yearly
and the direct cause of hunger and econom-
ic hardship in the tropical highlands of Asia,
Africa,and South/Central America.Therefore,
effective management of bacterial wilt
diseases worldwide is critical and requires
additional research for development of new
diagnostic tools for R3b2. It also requires
effective training of growers, official regula-
tors,diagnosticians and other individuals
responsible for first detection and manage-
ment of this pathogen. Hence,a Ralstonia
solanacearum/bacterial wilt dedicated
website (http://plantpath.ifas.ufl.edu/rsol/)
that aims to provide up-to-date information
on R.solanacearum for best management of
the diseases it causes on potato, tomato, and
geranium,is now available. *

The authors gratefully acknowledge mon-
etary support from USDA-CSREES Plant
Biosecurity Award 2007-55605-17843.

Anith, K. N., Momol, M. T, Kloepper, J. W, Marois, J.
J, Olson S. M., and Jones, J. B. 2004. Efficacy of plan t
growth-promoting rhizobacteria, acibenzolar-S-meth-
yl, and soil amendment for integrated management of
bacterial wilt on tomato. Plant Dis. 88:669-673.

APHIS-PPQ. 2005. Minimum sanitation protocols for
offshore geranium cutting production 2005. Issued
Dec. 1, 2005. USDA-APHIS-PPQ Pest Detection and
Management Programs, Riverdale, MD.

Boshou, L. 2005.A broad review and perspective
on breeding for resistance to bacterial wilt. Pages
225-238 in: Bacterial Wilt Disease and the Ralstonia
solanacearum Species Complex. C. Allen, P. Prior,
and A. C. Hayward, eds.American Phytopathological
Society, St. Paul, MN.

Chellemi, D. 0., Olson, S. M., and Mitchell, D. J. 1994.
Effects of soil solarization and fumigation on survival
ofsoilborne pathogens of tomato in north Florida.
Plant Dis.78:1167-1172.

Ciampi, L., and Sequeira, L. 1980. Influence of tem-
perature on virulence of Race 3 strains ofPseudomo-
nas solanacearum.Am. Potato J. 57:307-317.

Daughtrey, M. 2003. New and Re-emerging Diseases
in 2003. Department of Plant Pathology, Cornell
University, Long Island Horticultural Research &
Extension Center.

Denny, T. P.2006. Plantpathogenic Ralstonia species.
Pages 573-644 in: Plan t-associated bacteria. S. S.
Gnanamanickam, ed. Springer Publishing, Dordrecht,
The Netherlands.

Denny, T. P. and Hayward,A. C. 2001. Gram-negative
bacteria: Ralstonia. Pages 151-174 in: Laboratory
guide for identification of plant pathogenic bacteria,
3rd ed. Schaad, N. W.,Jones, J. B., and Chun, W., eds.
APS Press, St. Paul, MN.

Elphinstone,J. G. 2005. The current bacterial wilt
situation:A global overview. Pages 9-28 in: Bacterial
Wilt: The Disease and the Ralstonia solanacearum
Species Complex. C. Allen, P. Prior, and A. C. Hayward,
eds.American Phytopathological Society, St. Paul, MN.

Elphinstone,J. G, Hennessey, J., Wilson, J. K., and
Stead,D.E. 1996. Sensitivity of different methods for
the detection of Ralstonia solanacearum in potato
tuber extracts. EPPO Bull. 26:663-678.

Fegan, M., and Prior, P. 2005. How complex is the
"Ralstonia solanacearum species complex"? Pages
449-461 in: Bacterial Wilt Disease and the Ralstonia
solanacearum Species Complex. C. Allen, P. Prior,
and A. C. Hayward, eds.American Phytopathological
Society, St. Paul, MN.

Floyd,J. 2008. New Pest Response Guidelines: Ral-
stonia solanacearum race 3 biovar 2. USDA-APHIS-
PPQ-Emergency and Domestic Programs, Riverdale,
Maryland. http://www.aphis.usda.gov/import_ex-

Hanson, P. M., Wang, J. F, Licardo, 0., Hanudin, Mah,
S. Y, Hartman, G. L, Lin, Y C., and Chen,J. T. 1996.
Variable reactions of tomato lines to bacterial wilt
evaluated atseveral locations in SoutheastAsia.
HortScience 31:143-146.

Hayward,A.C. 1991. Biology and epidemiology of
bacterial wilt caused by Pseudomonas solanacearum.
Ann. Rev. Phytopathol. 29:65-87.

Ji, P., Momol, T., Olson, S., Meister, C., Norman, D., and

Jones,J.2007. Evaluation of phosphorous acid-
containing products for managing bacterial wilt of
tomato. Phytopathology 97:552.

Ji, P., Momol, M. T., Olson, S. M., and Pradhanang, P. M.
2005. Evaluation of thymol as biofumigant for con-
trol ofbacterial wilt oftomato under field conditions.
Plant Dis. 89:497-500.

Kelman, A. 1954. The relationship ofpathogenicity of
Pseudomonas solanacearum to colony appearance
in a tetrazolium medium. Phytopathology 44:693-

Kim, S. H., Olson, T. N., Schaad, N. W, and Moorman, G.
W. 2003. Ralstonia solanacearum Race 3, biovar 2, the
causal agent of brown rot ofpotato, identified in ge-
ranium in Pennsylvania, Delaware, and Connecticut.
Plant Dis.87:450.

Lambert, C. D. 2002. Agricultural Bioterrorism Protec-
tion Act of 2002: Possession, Use, and Transfer of
Biological;Agents and Toxins; Interim and Final Rule
(7 CFR Part331). Federal Register 67:76908-76938.

Lemay, A., Redlin, S., Fowler, G, and Dirani, M. 2003.
Pest data sheet: Ralstonia solanacearum race 3
biovar2. Published Feb., 12. USDA-APHIS-PPQ. Center
for plant health science and technology. Plant epide-
miology and risk analysis laboratory, Raleigh, NC.

McCarter, S. M. 1991. Bacterial wilt. Pages 28-29 in:
Compendium of tomato diseases.Jones, J. B.,Jones,J.
P., Stall, R. E., andZitter, TA., eds.APS Press Publisher:
St. Paul, MN.

Momol, T., Ji, P.,Jones, J., and Olson, S. 2005. Recom-
mended management strategies for bacterial wilt on
tomato caused by Ralstonia solanacearum. NFREC
Extension Report No: 2005-8.

Pradhanang, P.M.,Ji,P., Momol, MT., Olson,S.M.,
Mayfield,J. L. and Jones, J.B. 2005.Application of
acibenzolar-S-methyl enhances host resistance in
tomato against Ralstonia solanacearum. Plant Dis.
89: 989-993.

Prior, P., and Fegan, M. 2005. Recent developments
in the phylogeny and classification of Ralstonia
solanacearum.Acta Hort. 695:127-136.

Saddler, G. S. 2005. Management of bacterial wilt dis-
ease. Pages 121-132 in: Bacterial Wilt Disease and the
Ralstonia solanacearum Species Complex. C. Allen, P.
Prior, and A. C. Hayward, eds.American Phytopatho-
logical Society, St. Paul, MN.

Wang,J. F., Hanson, P, and Barnes,J.A. 1998. World-
wide evaluation of an internationalset of resistance
sources to bacterial wilt in tomato. Pages 269-275 in:
Bacterial Wilt Disease: Molecular and Ecological As-
pects. P. Prior, C.Allen, andJ. Elphinstone, eds. Springer
Verlag, Berlin, Germany.

Williamson, L., Hudelson, B. D., and Allen, C. 2002. Ral-
stonia solanacearum strains isolated from geranium
belong to Race 3 and are pathogenic on potato. Plant





John VanSickle and Richard Weldon
University of Florida/IFAS, Food& Resource Economics Dept., Gainesville, FL, sickle@ufl.edu

Bacterial spot on tomatoes is a serious
disease that is caused by a mobile bacte-
rium Xanthomonas campestrispv. vesicatoria
(Xcv). Disease development is favored by
temperatures of 24-32C, high humidity and
rain (Momol etal.,2008). Disease symptoms
include dark brown and circular spots on the
leaves, stems and fruit spurs. Fruit lesions
caused by the disease will cause the fruit
to not be marketable. The disease causes
serious problems every year on tomatoes in
Bacterial spot will impact the productivity
of the crop and could result in additional
expenses to control its development. The
impact of this disease is significant given the
regularity with which it impacts the Florida
tomato industry and the severity of its im-
pact in fields that suffer from it. It could have
effects that range from a modest impact on
marketable fruit yield to total plant collapse
and total crop loss. It is important to under-
stand these impacts to estimate the severity
of the disease and the potential returns
to programs that lead to its control. It is
important that growers understand the risk
associated with this disease and the impact
the disease can have on the profitability of
their farming operation.
This research estimates the impact of
bacterial spot on tomatoes fora represen-
tative farm in southwest Florida. Budgets
developed at the University of Florida (Van-
Sickle et al., 2009) were used to model a farm
that grows 272 acres of fresh-market, round
tomatoes. This representative farm model
is a risk-based model that accounts for risk
associated with yield and price. For this
project,the risk that bacterial spot adds to
yield risk is accounted for by estimating the
incidence and impact of bacterial spot on
farms in southwest Florida from the 1998/99
to 2007/08 seasons.Those disease incidence
measures are then correlated with yield to
develop the risk-based model that is used to
estimate the impact of bacterial spot on the
returns to growing tomatoes over a 10 year
period. The model allows us to estimate

a baseline foran operation that does not
suffer from bacterial spot and to compare
actual experience with that baseline.

A representative farm model for a grower of
fresh-market, round tomatoes in southwest
Florida was developed to assess the impact
of bacterial spot in Florida. The model was
developed using Simetar@ (Richardson,et
al.,2006),an Excel add-in that was devel-
oped explicitly for stochastic simulation
modeling. Here,Simetaris used to model
the representative activities of a Florida
tomato grower located in Southwest Florida.
The model simulates the farm's financial
results over a ten-year period based on
production costs estimated byVanSickle
and Smith (2009) for a fall tomato crop of
272 acres. This grower is expected to incur
variable costs of $6,400.52 for growing
tomatoes in 2007/08 and harvest and mar-
keting costs of $5,235 per acre for a yield of
1,500 25-lbs cartons per acre. Based on an-
nual cash operating and fixed costs and ex-
pected prices and yields an annual income
statement,an annual cash flow statement,
and balance sheets are forecast. Since this
is a stochastic simulation, pseudo-random
prices and yields are drawn from a multi-
variate empirical distribution. The random
yields and prices are correlated based on
historical correlations. Yields are estimated
forthe simulation based on recorded yields
as reported by a growerwho produced on
19 different fields in southwest Florida from
1998/99 to 2007/08. Because fields were
not always planted and also because of
missing data, the total number of observa-
tions provided by the grower was 71. The
grower also provided scouting data for the
incidence of bacterial spot in the fields over
the course of the crop in each of these fields.
The data allowed us to estimate a probabil-
ity distribution function for bacterial spot
in fresh market tomatoes and to correlate
bacterial spot with yields within those fields.
The scouting data provided by the

TABLE 1. Bacterial spot index as related to the
Horsfall Barratt (HB) scale for measuring the
incidence of plant disease.
BS Index HB Scale Relative Leaf
Area Affected
0 1 0
0.25-1 2 0 to 3
1.25-1.5 3 3 to 6
1.75-2 4 6 to 12
2.25-2.5 5 12 to 25
2.75-3.25 6 25 to 50
3.5-3.75 7 50 to 75
4 8 75 to 87
4.25-4.5 9 87 to 94
4.75-5 10 94 to 97
5 11 97 to 100
5 12 100

grower provided a measure of incidence
and severity for bacterial spot in the fields. A
Bacterial Spot (BS) index of 0 to 5 was used
to measure the severity of bacterial spot
incidence in the field (Table 1). The index
corresponds to the Horsfall Barrattt scale
for measuring plant disease (Horsfall and
Barrett, 1945). Weekly measures were ob-
served for 1 to 6 weeks after planting. These
measures were used to estimate a slope
coefficient for the spread of bacterial spot in
the field over the first six weeks after plant-
ing. The slope coefficients ranged in value
from -0.0002 (meaning a small incidence
was reported that was not present at the
end of the six weeks) to 0.614,with an aver-
age value of 0.2174. Yield data in the fields
ranged from 483 to 2,319 25-lbs cartons per
acre,with an average yield overthis period
of 1,454 cartons/acre.
Correlation coefficients were estimated
for yield with both the slope coefficient
and the absolute scouting index measure
for the sixth week after planting. The cor-
relation coefficient for the slope measure
was -0.397 while the correlation coef-
ficient for the sixth week scouting index
measure was -0.416. For purposes of the
impact analysis the sixth week scouting
measure was used to simulate the inci-


dence and severity of bacterial spot.
Prices for fresh market tomatoes are mod-
eled from price data for southwest Florida
provided by the Florida Tomato Committee
(Florida Tomato Committee,Annual Reports
1999 2008). A probability distribution
function for price was estimated from this
data and correlated with yields to produce
price and yield estimates for a simulation of
the grower's returns over 10 year horizon
given the state of technology that evolved
from 1998/99 to 2007/08.
The simulation provides an estimate of
the networth provided by growing toma-
toes given the current state of technology
and incidence of bacterial spot. The model
is then altered to remove the incidence of
bacterial spot to provide an estimate of net
worth should the farmer operate with no
risk associated with bacterial spot. The dif-
ference between the simulations provides
an estimate of the cost of bacterial spot
within this representative farm.

A simple regression of yield on trend and
the sixth week scouting measure indicates
that yields will decrease by 214.7 cartons per
acre for each unit increase in the sixth week
scouting index for bacterial spot (Table 1).
The average bacterial spot measure in this
data is 1.05 (Fig. 1),indicating that bacte-
rial spot has caused an average decrease
in yields of 225 cartons per acre over the
period 1998/99 to 2007/08 (equal to the
BS scout parameter 214.7 multiplied by
the average BS index observation of 1.05).
Given average prices of $13.71/25-lb carton
experienced in 2007/08,the total revenues
lost from this type of impact was $3,090 per
acre. A representative grower with 272 acres
who experienced an average incidence of
bacterial spot in 2007/08 lost $892,704 in
total revenues from this disease.
The simulation for the 272 acre farm that
grows tomatoes with the risk of bacterial
spot continuing shows that the change in
TABLE 2. Regression results for field yield
regressed on sixth week bacterial spot index.
Coefficient Parameter Standard t-test
estimate error
Intercept 1,675 74.7 22.43
BS Index -214.7 57.2 -3.75
R2 0.173

FIGURE 1. Probability distribution for observed bacterial spot (BS) index for farm operating in
southwest Florida.
PDF Approximation

0.000 0.500 1.000 1.500 2.00 2.500 3.000 3.500
Series 1

the net present value of net worth is ex-
pected to be a loss of $172,190. The model
indicates that there is an 87% probability
that this grower will lose net worth if he
continues to grow 272 acres over the next
10 years. If the risk of bacterial spot is elimi-
nated, then that expected loss in net worth
is reduced to $51,037,a gain of $121,190 for
this representative grower. The risk of losing
net worth is still significant at 62%, but the
probability is lowered by 25% as a result of
removing bacterial spot as a threat.
The simulation was also used to evaluate
the investment that could be made to elimi-
nate the threat of bacterial spot in tomatoes.
The model was run with increased costs
where the threat of bacterial spot is elimi-
nated, but where the financial result (change
in net worth) is the same as with the threat
of bacterial spot. The results indicate that
a farm could invest as much as $537.50 per
acre in technology and production practices
to eliminate the threat of bacterial spot,
with the expected outcome on net worth
as good as or better than it is without any
new technology or production practice that
eliminates the threat that exists today.

Bacterial spot is a serious threat to fresh
tomato growers in Florida. The objective of
this study was to estimate the cost of bacte-
rial spot to a representative tomato grower
in southwest Florida. A stochastic farm level
simulation model was used to model the
production and financial activities of a rep-
resentative grower over a ten-year horizon,
using production budgets developed from
growers in southwest Florida,and scouting
data for incidence of bacterial spot on farms
in southwest Florida. The results suggest

there is an incentive to implement produc-
tion practices and technology that could
control the incidence of bacterial spot in to-
mato production. A farm could absorb up to
$537.50 in added production costs to control
bacterial spot and be equally as well off as
they are without that investment. Not only
will the farmer likely experience an increase
in net worth as a result of technology that
controls bacterial spot, but the risk of suffer-
ing negative returns in the operation would
be diminished with this technology. The
results indicate that the threat of losing net
worth in the operation is reduced by 25% by
eliminating the threat to this disease.*

The authors wish to acknowledge the con-
tributions of Diana Horvath of Two Blades
Foundation and Dr. Charles Mellinger of
Glades Crop Care, Inc. for providing the
data required to estimate the risk of bacte-
rial spot in southwest Florida tomatoes
and its impact on yield.

Florida Tomato Committee. 1999-2008."Florida tomato
committee annual report' Florida Tomato Committee,

Horsfall,J.G.andR.W.Barratt. 1945.An improved grading
system for measuring plant disease (abstract). Phytopa-

Momol, T.,J.Jones,S. Olson,A. Obradovic, B.Balogh and P
King.2008. Integrated management ofbacterialspot on
tomato in Florida."UF/IFAS EDIS PP 192. Gainesville, FL.

Richardson J.W., K.D.Schumann, and PA. Feldman.2006.
Simetar simulation for applied risk management, Ver-
sion 2006 TexasA&M University, College Station, TX.

VanSickle,John,ScottSmith and Eugene McAvoy.2009.
Production budget for tomatoes in the Southwest Florida
area,2007/08. UF/IFAS EDIS (submitted), Gainesville, FL.






Jane E. Polston1, David J. Schuster2 and James E. Taylor2
SUniversity of Florida/IFAS, Dept. of Plant Pathology, Gainesville, FL, jep@ufl.edu
2 University of Florida/IFAS, GCREC, Wimauma, FL

The recognition of wild plant reservoirs
can be a very important component of
the management of plant viruses. The
role and relative importance of weed
reservoirs in virus ecology varies with
the virus,the crop and the location. The
ecology of Tomato Yellow Leaf Curl virus
(TYLCV),a virus which appeared in Florida
in 1997 (Polston et al., 1997),is not well
understood. The whitefly vector has a
very wide reported range of plants upon
which it will feed (more than 500 plant
species). While we do know that there
are alternative crop hosts forTYLCV,we
do not know if wild plant species play
any role as reservoirs. This information
is important for the improvement of the
management ofTYLCV. One option that
has been proposed is a crop-free period
in the summer, between the spring and
fall crops. This crop-free period will not
be effective if there are wild plant species
present during the summer that will serve
as reservoirs ofTYLCV.
We conducted a survey of possible
TYLCV reservoirs and collected plants in
2008-2009. This is a challenging project
because there are hundreds of wild plant
species in the Manatee-Hillsborough
Counties area. Many species are widely
dispersed. In addition,we are expecting
that only a small percent of the plants of a
susceptible species would be infected. To
focus our collection and keep within the
budget allotted,we did not collect from
grasses or plants known not to be hosts
of the whitefly vector. Most of the plant
species were selected based on their abil-
ity to serve as hosts for whiteflies,and/or
the presence of virus-like symptoms. We
were looking for plants that could serve as
sources of virus for young tomato plants.

Different species of wild plants are pres-
ent at different times of the year so we
collected samples from plants at the early
part of the spring season,and then at the
end of the spring season in the Ruskin
tomato production region. Five sites in
Manatee Co.and one in Hillsborough Co.
were sampled. Plants were sampled in
and around tomato fields and came from
the following types of locations: tomato
field, ditch bank,edges of tomato fields,
edges of other fields,woody field edge,
fallow fields,and fence rows. The sites se-
lected were those where we had observed
TYLCV-infected tomatoes early in the
season,and therefore where it was likely a
weed host might exist.

Samples were collected, identified,and
frozen for laboratory analyses for the pres-
ence ofTYLCV. All samples were assayed
for the presence ofTYLCV using a nucleic
acid spot hybridization assay (NASHA).
Briefly, nucleic acid was extracted from
frozen samples, blotted onto nylon mem-
branes,and hybridized with a radioactive-
ly-labeled probe made from the genome
ofTYLCV. While this assay allows the rapid
processing of many samples, it is known
to give false positive results, especially on
plant samples that have a lot of latex and
polysaccharides (present in many tropical
wild plants). Therefore,the more specific
and sensitive polymerase chair reaction
(PCR) using primers which will amplify
TYLCV,was conducted on all samples
that gave a positive result in the NASHA.
DNA was extracted from samples that
were positive in the dot spot assay and
a PCR was run using appropriate prim-
ers. Samples positive by this assay will be

retested using a different set of primers to
confirm the first results.
Between February 2008 and February
2009,we collected 1,920 plants from 45
known species of wild plants from 15
different plant families (Table 1). We are
in the process of identifying the species of
approximately 227 of those samples. All of
the samples have been tested by NASHA
for the presence ofTYLCV. Approximately
326 samples gave a positive result in the
NASHA. Of those 103 have already been
tested by PCR and the rest are in the
process of being tested. TYLCV was not
detected in any of the plants tested. We
conclude that the samples which were
positive by NASHA were probably the
result of non-specific binding of the probe
to the sample.
This study will be completed within the
next few months. As of today, we do not
have any evidence that would suggest
that there is a wild plant species that is an
important reservoir forTYLCV in the sum-
mer months. If our data continue along
this trend, it would suggest that there are
no obvious impediments,in terms of wild
plant species, to the success of a tomato-
free period. This is not to say that there
are no wild plant hosts, since our study
was not exhaustive, but that we did not
find any likely candidates. At this point, it
might be worth implementing a host free
period in the summer months on a trial

Polston,J.E., R.J. McGovern, and L.G. Brown. 1999. In-
troduction of Tomato yellow leaf curl virus in Florida
and implications for the spread of this and other
geminiviruses of tomato. Plant Disease 83:984-988.


TABLE 1. Wild plants sampled from the fields and tested for presence of TYLCV in and around tomato fields in Manatee and Hillsborough Counties,

Family Species Common Name County No. of No. Positive by NASHA
Samples Tested
Amaranthaceae Amaranthus viridis Slender amaranth Manatee 40 10
Amaranthus. spp. 10 0
Anacardiaceae Schinus terebinthifolius Brazilian pepper Manatee 20 0
Asteraceae Ambrosia artemisiifolia Common ragweed Manatee 50 0
Bidens pilosa L. Spanish needle Manatee, Hillsborough 170 0
Bidens spp. Manatee 61 0
Heterotheca subaxillaris Camphorweed Manatee 40 0
Lactuca canadensis Wild lettuce Manatee 20 0

Pseudognaphalium sp. cudweed Manatee 20 0
Chenopodiaceae Chenopodium album L. Lambs quarters Manatee 19 0
C. ambrosioides L. Mexican tea Manatee 80 0

C. sp. chenopodium Manatee 40 0
Commelinaceae Commelina diffusa Burm. f. Spreading dayflower Manatee 20 0
Euphorbaceae Euphorbia hirta L. Garden spurge Manatee 10 0
Euphorbia spp. spurge Manatee 40 0
Poinsettia cyanthophero (Mur- Wild poinsettia Manatee 30 0
ray) Bartling
Ricinus communis L. Castorbean Manatee 14 0

Fabaceae Crotalaria spectabilis Roth showy crotalaria Manatee 10 0
Indigofera hirsuta L Hairy indigo Manatee, Hillsborough 127 71
Melilotus alba White sweet clover Manatee 40 0
Phaseolus sp. (narrow leaf) phasebean 20 0
Phaseolus sp. (broad leaf) phasebean 10 7
Sesbania sp. Scop Hemp sesbania Manatee 71 40
Trifolium sp. Clover sp. Manatee 21 0
Lythraceae Lagerstroemia sp. Crape myrtle Manatee 11 0
Malvaceae Abutilon permolle coastal indian mallow Manatee 7 0
Abutilon sp. Indian mallow Manatee 20 0
Sida spinosa L. Sida Manatee 31 0
S. rhombifolia L. Indian hemp Manatee 20 1
Sida. sp. Sida Manatee, Hillsborough 50 0
Urena lobata Caesar-weed Manatee 111 23

Myricaceae Myrica cerifera wax myrtle Manatee 5 4
Onagraceae Ludwigia peruviana Primrose willow Manatee, Hillsborough 70 20
Ludwigia spp." Hillsborough 63 26
Oenothera laciniata Cutleaf primrose Manatee 60 3
Polygonaceae Rumex crispus curly dock Manatee 20 20
Rubiaceae Richardia brasiliensis Brazilian pusley Manatee 30 0
R. scabra L. Florida pusley Manatee, Hillsborough 65 10
Solanaceae Physalis spp. Manatee 20 0
Solanum americanum Mill. Nightshade Manatee 42 0
Solanum esculentum L. Cultivated tomato Manatee 10 10

S. ptycanthum Dun. Eastern nightshade Manatee 21 0
S. viarum Dunal Tropical soda apple Manatee 10 0
Verbenaceae Lantana sp. Lantana Manatee 28 0
Phyla nodiflora Mat lippia Manatee 10 0
Unknown Unknown unknown Manatee 233 80




Stephen M. Olson1 and Eugene McAvoy2
SUniversity of Florida/IFAS, NFREC, Quincy, FL, smolson@ufl.edu
2 Hendry County Extension, University of Florida, LaBelle, FL

Variety selections, often made several
months before planting,are one of the
most important management decisions
made by the grower. Failure to select the
most suitable variety or varieties may lead
to loss of yield or market acceptability. The
following characteristics should be consid-
ered in selection of tomato varieties for use
in Florida.
Yield. The variety selected should have
the potential to produce crops at least
equivalent to varieties already grown. The
average yield in Florida is currently about
1400 25-pound cartons per acre. The
potential yield of varieties in use should
be much higher than average.
Disease Resistance. Varieties selected
for use in Florida must have resistance to
Fusarium wilt, race 1,race 2 and in some
areas race 3;Verticillium wilt (race 1); Gray
leaf spot; and some tolerance to Bacte-
rial soft rot. Available resistance to other
diseases may be important in certain
situations,such as Tomato Yellow Leaf Curl
in south and central Florida and Tomato
spotted wilt and Bacterial wilt resistance
in northwest Florida.
Horticultural Quality. Plant habit, stem
type and fruit size, shape, color, smooth-
ness and resistance to defects should all
be considered in variety selection.
Adaptability. Successful tomato variet-
ies must perform well under the range of
environmental conditions usually encoun-
tered in the district or on the individual
Market Acceptability. The tomato
produced must have characteristics ac-
ceptable to the packer,shipper,wholesaler,
retailer and consumer. Included among
these qualities are pack out,fruit shape,
ripening ability,firmness,and flavor.

Many tomato varieties are grown com-
mercially in Florida, but only a few rep-
resent most of the acreage. In years past

we have been able to give a breakdown
of which varieties are used and predomi-
nantly where they were being used but
this information is no longer available
through the USDA Crop Reporting Service.

Table 1 shows results of Spring 2008 to-
mato trial conducted at the North Florida
Research and Education Center.

The following varieties are currently popu-
lar with Florida growers or have done well
in university trials. It is by no means a
comprehensive list of all varieties that may
be adapted to Florida conditions. Growers
should try new varieties on a limited basis
to see how they perform for them.

Amelia. Vigorous determinate, main
season,jointed hybrid. Fruit are firm and
aromatic suitable for green or vine ripe.
Good crack resistance. Resistant:Verticil-
lium wilt (race 1), Fusarium wilt (race 1,2,3),
root-knot nematode,Gray leaf spot and
Tomato spotted wilt. (Harris Moran).
Bella Rosa. Midseason maturity. Heat
tolerant determinate type. Produces large
to extra-large,firm, uniformly green and
globe shaped fruit. Variety is well suited for
mature green or vine-ripe production. Re-
sistant:Verticillium wilt (race 1), Fusarium
wilt (race 1,2),Tomato spotted wilt. (Sakata)
BHN 586. Midseason maturity. Fruit are
large to extra-large,deep globed shaped
with firm, uniform green fruits well suited
for mature green or vine-ripe production.
Determinate, medium to tall vine. Resis-
tant:Verticillium wilt (race 1),Fusarium wilt
(race 1,2) Fusarium crown rot and root-knot
nematode. (BHN)
BHN 602. Early-midseason maturity.
Fruit are globe shape but larger than BHN

640,and green shouldered. Resistant:
Verticillium wilt (race 1), Fusarium wilt (race
1,2,3) and Tomato spotted wilt. (BHN).
BHN 640. Early-midseason maturity.
Fruit are globe shape but tend to slightly
elongate,and green shouldered. Resistant:
Verticillium wilt (race 1), Fusarium wilt (race
1,2,3) and Tomato spotted wilt. (BHN).
Crista. Midseason maturity. Large,deep
globe fruit with tall robust plants. Does
best with moderate pruning and high
fertility. Good flavor, color and shelf-life.
Resistant:Verticillium wilt (race 1),Fusarium
wilt (race 1,2,3),Tomato spotted wilt and
root-knot nematode. (Harris Moran)
Crown Jewel. Uniform fruit have a deep
oblate shape with good firmness, quality
and uniformly-colored shoulders. Deter-
minate with medium-tall bush. Resistant:
Verticillium wilt (race 1),Fusarium wilt (race
1,2) Fusarium crown rot,Alternaria stem
canker and Gray leaf spot. (Seminis)
Fletcher. Midseason maturity. Large,
globe to deep oblate fruit with compact
plants. Does best with moderate prun-
ing and high fertility. Good flavor, color
and shelf-life. For vine ripe use only due
to nipple characteristic on green fruit.
Replacement for'Mountain Spring'where
Tomato spotted wilt is a problem. Resis-
tant:Verticillium wilt (race 1), Fusarium wilt
(race 1,2,3),Tomato spotted wilt and root-
knot nematode.
Flora-Lee. It was released for the
premium tomato market. A midseason,
determinate,jointed hybrid with moderate
heat-tolerance. Fruit are uniform green
with a high lycopene content and deep
red interior color due to the crimson gene.
Resistant: Fusarium wilt (race 1,2,3),Verticil-
lium wilt (race 1),and Gray leaf spot. For
Florida 47. A late midseason,determi-
nate,jointed hybrid. Uniform green,globe-
shaped fruit. Resistant: Fusarium wilt (race
1,2),Verticillium wilt (race 1),Alternaria
stem canker,and Gray leaf spot. (Seminis).


Florida 91. Uniform green fruit borne
on jointed pedicels. Determinate plant.
Good fruit setting ability under high tem-
peratures. Resistant:Verticillium wilt (race
1),Fusarium wilt (race 1,2),Alternaria stem
canker,and Gray leaf spot. (Seminis)
HA 3073. A midseason, determinate,
jointed hybrid. Fruit are large,firm, slightly
oblate and are uniformly green. Resistant:
Resistant:Verticillium wilt (race 1),Fusarium
wilt (race 1,2), Gray leaf spot,Tomato yellow
leaf Curl and Tomato mosaic. (Hazera)
Linda. Main season. Large round,
smooth, uniform shouldered fruit with
excellent firmness and a small blossom end
scar. Strong determinate bush with good
cover. Resistant:Verticillium wilt (race 1),
Fusarium wilt (race 1,2),Alternaria stem
canker and Gray leaf spot. (Sakata)
Phoenix. Early mid-season. Fruit are
large to extra-large, high quality,firm,
globe-shaped and are uniformly-colored.
"Hot-set"variety. Determinate, vigorous
vine with good leaf cover for fruit protec-
tion. Resistant:Verticillium wilt (race 1),
Fusarium wilt (race 1,2),Alternaria stem
canker and Gray leaf spot. (Seminis)
Quincy. Full season. Fruit are large to
extra-large, excellent quality,firm, deep
oblate shape and uniformly colored. Very
strong determinate plant. Resistant:Verti-
cillium wilt (race 1), Fusarium wilt (race 1,2),
Alternaria stem canker,Tomato spotted wilt
and Gray leaf spot. (Seminis)
RPT 6153. Main season. Fruit have
good eating quality and fancy appearance
in a large sturdy shipping tomato and are
firm enough for vine-ripe. Large determi-
nate plants. Resistant:Verticillium wilt (race
1), Fusarium wilt (race 1,2) and Gray leaf
spot. (Seedway)
Sanibel. Main season. Large,firm,
smooth fruit with light green shoulder and
a tight blossom end. Large determinate
bush. Resistant:Verticillium wilt (race 1),
Fusarium wilt (race 1,2), root-knot nema-
todes, Alternaria stem canker and Gray leaf
spot. (Seminis)
Sebring. A late midseason determinate,
jointed hybrid with a smooth,deep oblate,
firm,thick walled fruit. Resistant:Verticil-
lium wilt (race 1),Fusarium wilt (race 1,2,3),
Fusarium crown rot and Gray leaf spot.

SecuriTY 28. An early season determi-
nate variety with a medium vine and good
leaf cover adapted to different growing
conditions. Produces extra large, round and
firm fruit. Resistant: Alternaria stem canker,
Fusarium wilt (race 1 and 2),Gray leaf spot,
Tomato yellow leaf curl and Verticillium wilt
(race 1). (Harris Moran)
Solar Fire. An early, determinate,jointed
hybrid. Has good fruit setting ability under
high temperatures. Fruit are large, flat-
round, smooth, firm,light green shoulder
and blossom scars are smooth. Resistant:
Verticillium wilt (race 1), Fusarium wilt
(race 1,2 and 3) and gray leaf spot. (Harris
Solimar. A midseason hybrid produc-
ing globe-shaped, green shouldered fruit.
Resistant:Verticillium wilt (race 1), Fusarium
wilt (race 1 and 2),Alternaria stem canker,
gray leaf spot. (Seminis).
Soraya. Full season. Fruit are high qual-
ity, smooth and tend toward large to extra-
large. Continuous set. Strong, large bush.
Resistant:Verticillium wilt (race 1), Fusarium
wilt (race 1,2,3), Fusarium crown rot and
Gray leaf spot. (Syngenta, Rogers Seed)
Talladega. Midseason. Fruit are large
to extra-large,globe to deep globe shape.
Determinate bush. Has some hot-set abil-
ity. Performs well with light to moderate
pruning. Resistant:Verticillium wilt (race
1), Fusarium wilt (race 1,2),Tomato spotted
wilt and Gray leaf spot. (Syngenta, Rogers
Tygress. A midseason,jointed hybrid
producing large,smooth firm fruit with
good packouts. Resistant: Verticillium wilt
(race 1), Fusarium wilt (race 1 and 2),gray
leaf spot,Tomato mosaic and Tomato yel-
low leaf curl. (Seminis).

BHN 410. Midseason. Large,smooth,
blocky,jointless fruit tolerant to weather
cracking. Compact to small bush with
concentrated high yield. Resistant:Verticil-
lium wilt (race 1), Fusarium wilt (race 1,2),
Bacterial speck (race 0) and Gray leaf spot.
(BHN Seed)
BHN 411. Midseason. Large,smooth,
jointless fruit is tolerant to weather cracks
and has reduced tendency for graywall.
Compact plant with concentrated fruit set.

Resistant:Verticillium wilt (race 1),Fusarium
wilt (race 1,2), Bacterial speck (race 0) and
Gray leaf spot. (BHN Seed)
BHN 685. Midseason. Large to extra-
large, deep blocky, globe shaped fruit.
Determinate, vigorous bush with no prun-
ing recommended. Resistant:Verticillium
wilt (race 1), Fusarium wilt (race 1,2,3) and
Tomato spotted wilt. (BHN Seed)
Mariana. Midseason. Fruit are predomi-
nately extra-large and extremely uniform in
shape. Fruit wall is thick and external and
internal color is very good with excellent
firmness and shelf life. Determinate,small
to medium sized plant with good fruit set.
Resistant:Verticillium wilt (race 1),Fusarium
wilt (race 1,2), root-knot nematode, Alter-
naria stem canker and tolerant to Gray leaf
spot. (Sakata)
Monica. Midseason. Fruit are elongated,
firm,extra-large and uniform green color.
Vigorous bush with good cover. Resistant:
Verticillium wilt (race 1), Fusarium wilt (race
1,2), Bacterial speck (race 0) and Gray leaf
spot. (Sakata)
Plum Dandy. Medium to large determi-
nate plants. Rectangular,blocky, defect-free
fruit for fresh-market production. When
grown in hot, wet conditions, it does not
set fruit well and is susceptible to bacterial
spot. For winter and spring production in
Florida. Resistant:Verticillium wilt, Fusarium
wilt (race 1), Early blight,and rain checking.
(Harris Moran).
Sunoma. Main season. Fruit are
medium-large,elongated and cylindrical.
Plant maintains fruit size through multiple
harvests. Determinate plant with good
fruit cover. Resistant:Verticillium wilt (race
1), Fusarium wilt (race 1,2), Bacterial speck
(race 0), root-knot nematodes,Tomato
mosaic and Gray leaf spot. (Seminis)

BHN 268. Early. An extra firm cherry
tomato that holds, packs and ships well.
Determinate, small to medium bush with
high yields. Resistant: Verticillium wilt (race
1),Fusarium wilt (race 1). (BHN Seed)
Camelia. Midseason. Deep globe,
cocktail-cherry size with excellent firm-
ness and long shelf life. Indeterminate
bush. Outdoor or greenhouse production.
Verticillium wilt (race 1), Fusarium wilt (race



TABLE 1. Tomato variety trial results, Spring, 2008. North Florida Research and Education Center,
Marketable Yield (251b cartons/A) Marketable Fruit Size
Entry Source Extra Large Extra Large (%) (oz)
Tous 91 Hazera Seeds 2108 a 2179 a 75.9 a-c 8.4 a
Inbar Hazera Seeds 1365 b 1996 a 75.7 a-c 6.0 de
BHN 602 BHN 1001 b-d 1478 b 77.2 a 6.0 de
*Quincy Seminis 912 c-e 1463 bc 77.7 a 6.0 de
Fla. 8363 GCREC 1147 bc 1438 bc 78.1 a 6.5 b-d
NC 086 NCS 928 c-e 1280 b-d 70.4 a-d 6.1 c-e
Finishline Syngenta 928 c-e 1225 b-d 71.1 a-d 6.5 b-d
Nico Harris Moran 792 c-e 1216 b-d 71.1 a-d 5.7 e
Red Defender Harris Moran 811 c-e 1215 b-d 73.1 a-d 6.1 c-e
NC 07246 NCS 893 c-e 1198 b-d 76.5 ab 6.2 c-e
Amelia Harris Moran 903 c-e 1186 b-d 74.5 a-d 6.2 c-e
Mountain Glory NCS 834 c-e 1148 b-d 72.5 a-d 6.2 c-e
Redline Syngenta 874 c-e 1139 b-d 74.9 a-d 6.3 c-e
SecuriTY 28 Harris Moran 890 c-e 1058 b-d 72.2 a-d 7.1 b
Fla. 8153 GCREC 653 d-f 1029 b-d 72.7 a-d 5.7 e
NC 07235 NCS 666 d-f 1014 b-d 73.0 a-d 5.7 e
Fla. 8612 GCREC 836 c-e 995 cd 75.1 a-c 6.8 bc
Fletcher NCS 692 d-f 992 cd 72.6 a-d 5.9 de
Bella Rosa Sakata 700 d-f 923 de 67.4 b-d 6.3 c-e
NC 0694 NCS 553 ef 894 de 70.3 a-d 5.7 e
Crista Harris Moran 501 ef 802 de 71.1 a-d 5.7 e
Florida 47 Seminis 326 f 496 e 66.8 cd 5.9 de
Fla. 8413 GCREC 308 f 492 e 65.6 d 5.8 e
zMean separation by Duncan's Multiple Range Test, 5% level. Comments: In-row spacing 20 inches, 6-ft between-row spacing.
Trickle irrigation under blackpolyethylene mulch. Fertilizer applied 196-56-196 Ib/A N-P205-K20. Seeded: 18 February,
transplanted: 7 April, 3 harvests between 24 June and 9 July.

1) and Tobacco mosaic. (Siegers Seed)
Cherry Blossom. 70 days. Large cherry,
holds and yields well. Determinate bush.
Resistant:Verticillium wilt (race 1),Fusarium
wilt (race 1,2), Bacterial speck (race 0), root-
knot nematodes, Alternaria stem canker
and Gray leaf spot. (Seedway)
Mountain Belle. Vigorous,determinate
type plants. Fruit are round to slightly
ovate with uniform green shoulders borne
on jointless pedicels. Resistant: Fusarium
wilt (race 2),Verticillium wilt (race 1). (Syn-
genta Rogers Seed).
Shiren. Compact plant with high yield
potential and nice cluster. Resistant: Fu-
sarium wilt (race 1,2), root-knot nematodes
and Tomato mosaic. (Hazera)
Super Sweet 100 VF. Produces large
clusters of round uniform fruit with high
sugar levels. Fruit somewhat small and may
crack during rainy weather. Indeterminate
vine with high yield potential. Resistant:

Red Grape. 68 days. Vigorous indeter-
minate bush. Firm excellent shaped fruit
weighing 8-15 g.
Santa. 75 days. Vigorous indeterminate
bush. Firm elongated grape-shaped fruit
with outstanding flavor and up to 50 fruits
per truss. Resistant:Verticillium wilt (race 1),
Fusarium wilt (race 1), root-knot nematodes
and Tobacco mosaic. (Thompson and
St. Nick. Mid-early season. Indetermi-
nate bush. Oblong,grape-shaped fruit with
brilliant red color and good flavor. Up to
10% brix. (Siegers Seed)
Smarty. 69 days. Vigorous, indetermi-
nate bush with short internodes. Plants are
25% shorter than Santa. Good flavor, sweet
and excellent flavor. (Seedway)
Sweethearts. Indeterminate bush with
intermediate internodes. Brilliant red,firm,
elongated grape-shaped fruit. Matures
between 70 and 75 days. Good flavor, crack-
resistant and high brix. Resistant:Tobacco
mosaic virus.
Tami G. Early season. Indeterminate,
medium tall. Small fruits with nice shape.*

Verticillium wilt (race 1) and Fusarium wilt
(race 1). (Siegers Seed, Seedway)

Brixmore. Very early. Indeterminate.
Very uniform in shape and size,deep glossy
red color with very high early and total
yield. High brix and excellent firm flavor.
Resistant:Verticillium wilt (race 1), root-knot
nematodes and Tomato mosaic. (Harris
Cupid. Early. Vigorous, indeterminate
bush. Oval-shaped fruit have an excellent
red color and a sweet flavor. Resistant:
Fusarium wilt (race 1,2), Bacterial speck
(intermediate resistance race 0) and Gray
leaf spot. (Seminis)
Jolly Elf. Early season. Determinate
plant. Extended market life with firm,
flavorful grape-shaped fruits. Average 10%
brix. Resistant:Verticillium wilt (race 1), Fu-
sarium wilt (race 2) and cracking. (Siegers



University of Florida/IFAS, Horticultural Sciences Dept., Gainesville, FL, esimonne@ufl.edu

Water and nutrient management are two
important aspects of tomato production
in all production systems. Water is used for
wetting the fields before land preparation,
transplant establishment,and irrigation.
The objective of this article is to provide an
overview of recommendations for tomato
irrigation management in Florida. Irrigation
management recommendations should be
considered together with those for fertilizer
and nutrient management.
Irrigation is used to replace the amount
of water lost by transpiration and evapo-
ration. This amount is also called crop
evapotranspiration (ETc). Irrigation schedul-
ing is used to apply the proper amount
of water to a tomato crop at the proper
time. The characteristics of the irrigation
system,tomato crop needs,soil properties,
and atmospheric conditions must all be
considered to properly schedule irrigations.
Poor timing or insufficient water application
can result in crop stress and reduced yields
from inappropriate amounts of available
water and/or nutrients. Excessive water
applications may reduce yield and quality,
are a waste of water,and increase the risk of
nutrient leaching.
A wide range of irrigation scheduling
methods is used in Florida,which corre-
spond to different levels of water manage-
ment (Table 1). The recommended method
to schedule irrigation for tomato is to use
together an estimate of the tomato crop
water requirement that is based on plant
growth,a measurement of soil water status
and a guideline for splitting irrigation (water
management level 5 in Table 1;Table 2). The
estimated water use is a guideline for ir-
rigating tomatoes. The measurement of soil
water tension is useful for fine tuning irriga-
tion. Splitting irrigation events is necessary
when the amount of water to be applied is
larger than the water holding capacity of
the root zone.

Tomato water requirement (ETc) depends

TABLE 1. Levels of water management and corresponding irrigation scheduling methods for

Water Management Irrigation scheduling method
Level Rating
0 None Guessing (no specific rule is followed to irrigate)
1 Very low Using the "feel and see" method
2 Low Using systematic irrigation (example: 2 hrs every day from transplanting to
3 Intermediate Using a soil moisture measuring tool to start irrigation
4 Advanced Using a soil moisture measuring tool to schedule irrigation and apply amounts
based on a budgeting procedure
5 Recommended Using together a water use estimate based on tomato plant stage of growth, a
measurement of soil moisture, determining rainfall contribution to soil moisture,
having a guideline for splitting irrigation and keeping irrigation records.

TABLE 2. Summary of irrigation management guidelines for tomato.

Irrigation management component Irrigation system
Seepagey Dripx
1- Target water application rate Keep water table between 18 and 24 Historical weather data or crop
inch depth evapotranspiration (ETc) calculated
from reference ET or Class A pan
2- Fine tune application with soil Monitor water table depth with Maintain soil water tension in the
moisture measurement observation wells root zone between 8 and 15 cbar
3- Determine the contribution of Typically, 1 inch rainfall raises the Poor lateral water movement on
rainfall water table by 1 foot sandy and rocky soils limits the
contribution of rainfall to crop water
needs to (1) foliar absorption and
cooling of foliage and (2) water
funneled by the canopy through the
plan hole.
4- Rule for splitting irrigation Not applicable Irrigations greater than 12 and 50
gal/lOOft (or 30 min and 2 hrs for
medium flow rate) when plants are
small and fully grown, respectively
are likely to push the water front
being below the root zone
5-Record keeping Irrigation amount applied and total Irrigation amount applied and total
rainfall received" rainfall received"
Days of system operation Daily irrigation schedule
z Efficient irrigation scheduling also requires a properly designed and maintained irrigation systems
Y Practical only when a spodic layer is present in the field
x On deep sandy soils
* Required by the BMPs

on stage of growth,and evaporative de-
mand. ETc can be estimated by adjusting
reference evapotranspiration (ETo) with a
correction factor call crop factor (Kc; equa-
tion [1]). Because different methods exist
for estimating ETo, it is very important to
use Kc coefficients which were derived us-
ing the same ETo estimation method as will
be used to determine ETc. Also, Kc values
for the appropriate stage of growth and
production system (Table 3) must be used.
By definition, ETo represents the water

use from a uniform green cover surface,ac-
tively growing,and well watered (such as a
turf or grass covered area). ETo can be mea-
sured on-farm using a small weather sta-
tion. When daily ETo data are not available,
historical daily averages of Penman-method
ETo can be used (Table 4). However,these
long-term averages are provided as guide-
lines since actual values may fluctuate by as
much as 25%,either above the average on
hotter and drier than normal days, or below
the average on cooler or more overcast



TABLE 3. Crop coefficient estimates (Kc) for tomato'.
Tomato Growth Stage Corresponding Weeks After TransplantingY Kc for Drip-Irrigated Crops
1 1-2 0.30
2 3-4 0.40
3 5-11 0.90
4 12 0.90
5 13 0.75
SActual values will vary with time of planting, length of growing season and other site-specific factors. Kc values should be used
with ETo values in Table 2 to estimated crop evapotranspiration (ETc)
Y For a typical 13-week-long growing season

TABLE 4. Historical Penman-method reference
acre per day)z.

z Assuming water application over the entire area with 100% efficier

days than normal. As a result,SWT or soil
moisture should be monitored in the field.
Eq.[1] Crop water requirement = Crop
coefficient x Reference evapotranspira-
ETc = Kc x ETo
Tomato crop water requirement may also
be estimated from Class A pan evaporation
Eq. [2] Crop water requirement = Crop
factor x Class A pan evaporation
ETc = CF x Ep
Typical CF values for fully-grown
tomato should not exceed 0.75 (Locascio
and Smajstrla,1996). A third method for
estimated tomato crop water require-
ment is to use modified Bellani plates also
known as atmometers. A common model
ofatmomter used in Florida is the ETgage.
This device consists of a canvas-covered
ceramic evaporation plate mounted on a
water reservoir. The green fabric creates a
diffusion barrier that controls evaporation
at a rate similar to that of well water plants.
Water loss through evaporation can be read
on a clear sight tube mounted on the side
of the device. Evaporation from the ETgage

ET (ETo) for four Florida locations (in gallons per

(ETg) was well correlated to ETo except on
rainy days, but overall,the ETgage tended
to underestimate ETo (Irmak et al.,2005).
On days with rainfall less than 0.2 inch/day,
ETo can be estimated from ETg as: ETo =
1.19 ETg.When rainfall exceeds 0.2 inch/day,
rain water wets the canvas which interferes
with the flow of water out of the atmom-
eters,and decreases the reliability of the

Irrigation systems are generally rated with
respect to application efficiency (Ea),which
is the fraction of the water that has been
applied by the irrigation system and that
is available to the plant for use. In general,
Ea is 20% to 70% for seepage irrigation
and 90% to 95% for drip irrigation. Applied
water that is not available to the plant may
have been lost from the crop root zone
through evaporation, leaks in the pipe
system, surface runoff, subsurface runoff,or
deep percolation within the irrigated area.
When dual drip/seepage irrigation systems
are used, the contribution of the seepage

system needs to be subtracted from the
tomato irrigation requirement to calculate
the drip irrigation need. Otherwise, exces-
sive water volume will be systematically
applied. Tomato irrigation requirement are
determined by dividing the desired amount
of water to provide to the plant (ETc), by Ea
as a decimal fraction (Eq. [3]).
Eq. [3] Irrigation requirement = Crop
water requirement / Application ef-
IR = ETc/Ea

For seepage-irrigated crops, irrigation
scheduling recommendations consist of
maintaining the water table near the 18-
inch depth shortly after transplanting and
near the 24- inch depth thereafter (Stanley
and Clark,2003). The actual depth of the
water table may be monitored with shal-
low observation wells (Smajstrla, 1997).
Irrigation scheduling for drip irrigated to-
mato typically consists in daily applications
of ETc, estimated from Eq.[1] or [2] above.
In areas where real-time weather informa-
tion is not available, growers use the"1,000
gal/acre/day/string" rule for drip-irrigated
tomato production. As the tomato plants
grow from 1 to 4 strings, the daily irrigation
volumes increase from 1,000 gal/acre/day
to 4,000 gal/acre/day. On 6-ft centers,this
corresponds to 15 gal/i 001bf/day and 60
gal/1001bf/day for 1 and 4 strings, respec-

Soil water tension (SWT) represents the
magnitude of the suction (negative pres-
sure) the plant roots have to create to free
soil water from the attraction of the soil
particles,and move it into its root cells.
The dryer the soil,the higher the suction
needed, hence, the higher SWT. SWT is
commonly expressed in centibars (cb) or
kiloPascals (kPa; 1 cb = I kPa). For tomatoes
grown on the sandy soils of Florida, SWT
in the rooting zone should be maintained
between 6 (field capacity) and 15 cb.
The two most common tools available
to measure SWTin the field are tensiom-
eters and time domain reflectometry (TDR)
probes,although other types of probes


Month Tallahassee Tampa West Palm Beach Miami
January 1,630 2,440 2,720 2,720
February 2,440 3,260 3,530 3,530
March 3,260 3,800 4,340 4,340
April 4,340 5,160 5,160 5,160
May 4,890 5,430 5,160 5,160
June 4,890 5,430 4,890 4,890
July 4,620 4,890 4,890 4,890
August 4,340 4,620 4,890 4,620
September 3,800 4,340 4,340 4,070
October 2,990 3,800 3,800 3,800
November 2,170 2,990 3,260 2,990
December 1,630 2,170 2,720 2,720

are now available (Muhoz-Carpena,2004).
Tensiometers have been used for several
years in tomato production. A porous cup
is saturated with water,and placed under
vacuum. As the soil water content changes,
water comes in or out of the porous cup,
and affects the amount of vacuum inside
the tensiometer. Tensiometer readings
have been successfully used to monitor
SWT and schedule irrigation for tomatoes.
However, because they are fragile and
easily broken by field equipment, many
growers have renounced to use them. In
addition, readings are not reliable when
the tensiometer dries, or when the contact
between the cup and the soil is lost.
Depending on the length of the access
tube,tensiometers cost between $40 and
$80 each. Tensiometers can be reused as
long as they are maintained properly and
remain undamaged.
It is necessary to monitor SWTattwo
soil depths when tensiometers are used. A
shallow 6-inch depth is useful at the begin-
ning of the season when tomato roots are
near that depth. A deeper 12-inch depth is
used to monitor SWT during the rest of the
season. Comparing SWT at both depths
is useful to understand the dynamics of
soil moisture. When both SWT are within
the 4-8 cb range (close to field capacity),
this means that moisture is plentiful in
the rooting zone. This may happen after
a large rain, or when tomato water use is
less than the irrigation applied. When the
6-inch-depth SWT increases (from 4-8 cb
to 10-15cb) while SWT at 12-inch depth
remains within 4-8 cb,the upper part of
the soil is drying,and it is time to irrigate.
If the 6-inch-depth SWT continues to rise
above 25cb,a water stress will result; plants
will wiltand yields will be reduced. This
should not happen under adequate water
A SWTat the 6-inch depth remaining
with the 4-8 cb range, but the 12-inch
depth reading showing a SWT of 20-25cb
suggest that deficit irrigation has been
made: irrigation has been applied to re-wet
the upper part of the profile only. The
amount of water applied was not enough
to wet the entire profile. If SWT at the
12-inch depth continues to increase,then
water stress will become more severe

TABLE 5. Estimated maximum water application (in gallons per acre and in gallons/1001fb) in one
irrigation event for tomato grown on 6-ft centers (7,260 linear bed feet per acre) on sandy soil
(available water holding capacity 0.75 in/ ft and 50% soil water depletion). Split irrigations may
be required during peak water requirement.

Wetting width (ft)


Gal/lOOft to
wet depth of

Gal/lOOft to
wet depth of

and it will become increasingly difficult to
re-wet the soil profile. The sandy soils of
Florida have a low water holding capacity.
Therefore, SWT should be monitored daily
and irrigation applied at least once daily.
Scheduling irrigation with SWT only can
be difficult at times.Therefore, SWT data
should be used together with an estimate
of tomato water requirement.
Time domain reflectometry (TDR) is an-
other method for measuring soil moisture.
The availability of inexpensive equipment
($400 to $550/unit) has recently increased
the potential of this method to become
practical for tomato growers. ATDR unit is
comprised of three parts:a display unit,a
sensor,and two rods. Rods may be 4 inches
or 8 inches in length based on the depth
of the soil. Long rods may be used in all
the sandy soils of Florida,while the short
rods may be used with the shallow soils of
Miami-Dade county.
The advantage ofTDR is that probes
need not be buried permanently,and
readings are available instantaneously. This
means that, unlike tensiometers,TDR can
be used as a hand-held, portable tool.
TDR actually determines percent soil
moisture (volume of water per volume of
soil). In theory,a soil water release curve
has to be used to convert soil moisture in
to SWT. However, because TDR provides
an average soil moisture reading over the
entire length of the rod (as opposed to the
specific depth used for tensiometers),it is
not practical to simply convert SWT into
soil moisture to compare readings from
both methods. Tests with TDR probes have
shown that best soil monitoring may be
achieved by placing the probe vertically,
approximately 6 inches away from the drip
tape on the opposite side of the tomato
plants. For fine sandy soils, 9% to 15% ap-
pears to be the adequate moisture range.
Tomato plants are exposed to water stress
when soil moisture is below 8%. Excessive

to wet depth
of 2 ft

Gal/acre to
wet depth
of 1 ft

Gal/acre to
wet depth of

Gal/acre to
wet depth
of 2 ft

irrigation may result in soil moisture above

For sandy soils,a one square foot verti-
cal section of a 100-ft long raised bed
can hold approximately 24 to 30 gallons
of water (Table 5). When drip irrigation
is used, lateral water movement seldom
exceeds 6 to 8 inches on each side of the
drip tape (12 to 16 inches wetted width).
When the irrigation volume exceeds the
values in Table 5, irrigation should be split
into 2 or 3 applications. Splitting will not
only reduce nutrient leaching, but it will
also increase tomato quality by ensuring
a more continuous water supply. Uneven
water supply may result in fruit cracking.

When overhead and seepage irrigation
were the dominant methods of irrigation,
acre-inches or vertical amounts of water
were used as units for irrigations recom-
mendations. There are 27,150 gallons in 1
acre-inch; thus,total volume was calcu-
lated by multiplying the recommendation
expressed in acre-inch by 27,150. This unit
reflected quite well the fact that the entire
field surface was wetted.
Acre-inches are still used for drip irriga-
tion,although the entire field is not wetted.
This section is intended to clarify the con-
ventions used in measuring water amounts
for drip irrigation. In short,water amounts
are handled similarly to fertilizer amounts,
i.e.,on an acre basis. When an irrigation
amount expressed in acre-inch is recom-
mended for plasticulture,it means that the
recommended volume of water needs to
be delivered to the row length present in a
one-acre field planted at the standard bed
spacing. So in this case, it is necessary to
know the bed spacing to determine the ex-



act amount of water to apply. In addition,
drip tape flow rates are reported in gallons/
hour/emitter or in gallons/hour/100 ft of
row. Consequently, tomato growers tend to
think in terms of multiples of 100 linear feet
of bed, and ultimately convert irrigation
amounts into duration of irrigation. It is
important to correctly understand the units
of the irrigation recommendation in order
to implement it correctly.

How long does an irrigation event need to
last if a tomato grower needs to apply 0.20
acre-inch to a 2-acre tomato field? Rows
are on 6-ft centers and a 12-ft spray alley is
left unplanted every six rows;the drip tape
flow rate is 0.30 gallons/hour/emitter and
emitters are spaced 1 foot apart.
1. In the 2-acre field,there are 14,520 feet
of bed (2 x 43,560/6). Because of the alleys,
only 6/8 of the field is actually planted. So,
the field actually contains 10,890 feet of
bed (14,520x 6/8).
2.A 0.20 acre-inch irrigation corresponds
to 5,430 gallons applied to 7,260 feet of
row,which is equivalent to 75gallons/
100feet (5,430/72.6).
3.The drip tape flow rate is 0.30 gal-
lons/hr/emitter which is equivalent to 30
gallons/hr/1 O0feet. It will take 1 hour to
apply 30 gallons/1 00ft,2 hours to apply
60gallons/100ft,and 2.2 hours to apply 75
gallons. The total volume applied will be
8,168 gallons/2-acre (75 x 108.9).

As an effort to clean impaired water
bodies,federal legislation in the 70's,fol-
lowed by state legislation in the 90's and
state rules since 2000 have progressively
shaped the Best Management Practices
(BMP) program for vegetable production
in Florida. Section 303(d) of the Federal
Clean Water Act of 1972 required states to
identify impaired water bodies and estab-
lish Total Maximum Daily Loads (TMDL)
for pollutants entering these water bodies.
In 1987,the Florida legislature passed the
Surface Water Improvement and Manage-
ment Act requiring the five Florida water
management districts to develop plans

to clean up and preserve Florida lakes,
bays, estuaries, and rivers. In 1999,the
Florida Watershed Restoration Act defined
a process for the development ofTMDLs.
The"Water Quality/quantity Best Manage-
ment Practices for Florida Vegetable and
Agronomic Crops" manual was adopted
by reference and by rule 5M-8 in the Flor-
ida Administrative Code on Feb. 8,2006
(FDACS,2005).The manual (available at
www.floridaagwaterpolicy.com) provides
background on the state-wide BMP pro-
gram for vegetables, lists all the possible
BMPs, provides a selection mechanism for
building a customized BMP plan,out-
lines record-keeping requirements,and
explains how to participate in the BMP
program. By definition, BMPs are specific
cultural practices that aim at reducing nu-
trient load while maintaining or increasing
productivity. Hence, BMPs are tools to
achieve the TMDL.Vegetable growers who
elect to participate in the BMP program
receive three statutory benefits: (1) a
waiver of liability from reimbursement
of cost and damages associated with the
evaluation, assessment, or remediation of
contamination of ground water (Florida
Statutes 376.307); (2) a presumption of
compliance with water quality standards
(F.S. 403.067 (7)(d)),and (3); an eligibility
for cost-share programs (F.S. 570.085 (1)).
BMPs cover all aspects of tomato pro-
duction: pesticide management, conserva-
tion practices and buffers, erosion control
and sediment management, nutrient and
irrigation management,water resources
management,and seasonal or temporary
farming operations. The main water qual-
ity parameters of importance to tomato
and pepper production and targeted by
the BMPs are nitrate, phosphate and total
dissolved solids concentration in surface or
ground water.All BMPs have some effect
on water quality, but nutrient and irrigation
management BMPs have a direct effect on
it. *

Cantliffe,D., P.Gilreath, D. Haman, C. Hutchinson,
Y. Li, G. McAvoy, K. Migliaccio, T. Olczyk, S. Olson, D.
Parmenter, B. San tos, S. Shukla, E. Simonne, C. Stanley,
and A. Whidden. 2009. Review of nutrient manage-
ment systems for Florida vegetable producers. EDIS
HS1156, http://edis.ifas.ufl.edu/HS 1156.

FDACS.2005. Florida Vegetable andAgronomic Crop
Water Quality and Quantity BMP Manual. Florida
Department ofAgriculture and Consumer Services

Irmak,S., M.Asce, M.D. Dukes, and J.M.Jacobs. 2005.
Using modified Bellani plate evapotranspiration
gauges to estimate short canopy reference evapo-
transpiration. J. Irr. Drainage Eng. (2):164-175.

Locascio,SJ. andA.G.Smajstrla. 1996. Water applica-
tion scheduling by pan evaporation for drip-irrigated
tomato.J.Amer. Soc.Hort.Sci. 121 (1):63-68
Munoz-Carpena, R. 2004. Field devices for monitoring
soil water content. EDIS Bul.343. http://edis.ifas.ufl.

Simonne, E.H., D.W.Studstill, R.C. Hochmuth, G. McA-
voy, M.D. Dukes and S.M. Olson. 2003. Visualization
of water movement in mulched beds with injections
of dye with drip irrigation. Proc. Fla. State Hort. Soc.

Simonne, E.H., D.W.Studstill, T.W. Olczyk, and R.
Munoz-Carpena.2004. Water movement in mulched
beds in a rockysoil ofMiami-Dade County. Proc. Fla.
State Hort. Soc 117:68-70.

Simonne, E. and B. Morgan. 2005. Denitrification in
seepage irrigated vegetable fields in South Florida,
EDIS, HS 1004, http://edis.ifas.ufl.edu/HS248.

Simonne, E.H., D.W. Studstill, R.C. Hochmuth, JT.Jones
and C. W. Starling. 2005. On-farm demonstration of
soil water movement in vegetables grown with plasti-
culture, EDIS,HS 1008, http://edis.ifas.ufl.edu/HS251.

Simonne, E.H. and M.D. Dukes. 2009. Principles of
irrigation management for vegetables, pp. 17-23. In:
S.M. Olson and E. Simonne (eds) 2009-2010 Vegetable
Production Handbook for Florida, Vance Publ.,
Lenexa, KS.

Smajstrla,A.G. 1997. Simple water level indicator for
seepage irrigation. EDIS Circ. 1188, http://edis.ifas.ufl.

Stanley, C.D. and G.A. Clark. 2003. Effect of reduced
water table and fertility levels on subirrigated tomato
production in Southwest Florida. EDIS SL-210, http://





Eric H. Simonne
University of Florida/IFAS, Horticultural Sciences Dept., Gainesville, FL, esimonne@ufl.edu

Fertilizer and nutrient management are
essential components of successful com-
mercial tomato production. This article
presents the basics of nutrient manage-
ment for the different production systems
used for tomato in Florida.

Prior to each cropping season, soil tests
should be conducted to determine fertil-
izer needs and eventual pH adjustments.
Obtain a UF/IFAS soil sample kit from the
local agricultural Extension agent or from
a reputable commercial laboratory for this
purpose. If a commercial soil testing labo-
ratory is used, be sure the laboratory uses
methodologies calibrated and extractants
suitable for Florida soils. When used with
the percent sufficiency philosophy, routine
soil testing helps adjust fertilizer applica-
tions to plant needs and target yields. In
addition,the use of routine calibrated soil
tests reduces the risk of over-fertilization.
Over fertilization reduces fertilizer effi-
ciency and increases the risk of groundwa-
ter pollution. Systematic use of fertilizer
without a soil test may also result in crop
damage from salt injury.
The crop nutrient requirements of
nitrogen, phosphorus, and potassium
(designated in fertilizers as N,P205,and
K20, respectively) represent the optimum
amounts of these nutrients needed for
maximum tomato production (Table 1).
Fertilizer rates are provided on a per-acre
basis for tomato grown on 6-ft centers.
Under these conditions,there are 7,260
linear feet of tomato row in a planted acre.
When different row spacings are used, it
is necessary to adjust fertilizer applica-
tion accordingly. For example,a 200 Ibs/A
N rate on 6-ft centers is the same as 240
Ibs/A N rate on 5-ft centers and a 170

TABLE 1. Fertilization recommendations for tomato grown in Florida on sandy soils testing very
low in Mehlich-1 potassium (K20).
Production Nutrient Recommended base fertilization Recommended supplemental
system fertilization
l P Injectedx Leaching Measured Extended
Total Preplant- rainrs low plant harvest
Ibs/A (Ibs/A) (Ibs/A/day) nutrient seasons
Weeks after transplanting
1-2 3-4 5-11 12 13
Drip irrigation, N 200 0-50 1.5 2.0 2.5 2.0 1.5 n/a 1.5 to 2 1.5-2 Ibs/A/
raised beds, and Ibs/A/day for dayp
polyethylene 7dayst
K20 220 0-50 2.5 2.0 3.0 2.0 1.5 n/a 1.5-2 1.5-2 Ibs/A/
Ibs/A/day for dayp
Seepage irriga- N 200 200' 0 0 0 0 0 30 30 Ibs/At 30 Ibs/Ap
tion, raised beds, Ibs/Aq
and polyethylene
K,0 220 220' 0 0 0 0 0 20 20 Ibs/At 20 Ibs/Ap
1 A = 7,260 linear bed feet per acre (6-ft bed spacing); for soils testing "very low" in Mehlich 1 potassium (K20).
y applied using the modified broadcast method (fertilizer is broadcast where the beds will be formed only, and not over the entire
field). Preplant fertilizer cannot be applied to double/triple crops because of the plastic mulch; hence, in these cases, all the fertil-
izer has to be injected.
x This fertigation schedule is applicable when no N and K20 are applied preplant. Reduce schedule proportionally to the amount
of N and K20 applied preplant. Fertilizer injections may be done daily or weekly. Inject fertilizer at the end of the irrigation event
and allow enough time for proper flushing afterwards.
w For a standard 13 week-long, transplanted tomato crop grown in the Spring.
SSome of the fertilizer may be applied with a fertilizer wheel though the plastic mulch during the tomato crop when only part of the
recommended base rate is applied preplant. Rate may be reduced when a controlled-release fertilizer source is used.
" Plant nutritional status may be determined with tissue analysis or fresh petiole-sap testing, or any other calibrated method. The
"low" diagnosis needs to be based on UF/IFAS interpretative thresholds.

Ibs/A N rate on 7-ft centers. This example
is for illustration purposes,and only 5 and
6 ft centers are commonly used for tomato
production in Florida.
Fertilizer rates can be simply and ac-
curately adjusted to row spacings other
than the standard spacing (6-ft centers) by
expressing the recommended rates on a
100 linear bed feet (Ibf) basis, rather than
on a real-estate acre basis. For example,
in a tomato field planted on 7-ft centers
with one drive row every six rows, there
are only 5,333 Ibf/A (6/7 x 43,560 / 7). If the
recommendation is to inject 10 Ibs of N
per acre (standard spacing),this becomes
10 Ibs of N/7,260 Ibf or 0.141bs N/100
Ibf. Since there are 5,333 Ibf/acre in this
example,then the adjusted rate for this
situation is 7.46 Ibs N/acre (0.14 x 53.33).
In other words,an injection of 10 Ibs of N

to 7,260 Ibf is accomplished by injecting
7.46 Ibs of N to 5,333 Ibf.

The optimum pH range for tomato is
6.0-6.5. This is the range at which the
availability of all the essential nutrients
is highest. Fusarium wilt problems are
reduced by liming within this range, but
it is not advisable to raise the pH above
6.5 because of reduced micronutrient
availability. In areas where soil pH is basic
(>7.0), micronutrient deficiencies may be
corrected by foliar sprays.
Calcium and magnesium levels should
be also corrected according to the soil
test. If both elements are"low'and lime is
needed, then broadcast and incorporate
dolomitic limestone (CaCO3,MgCO3).
Where calcium alone is deficient,"hi-cal"



(CaCO3) limestone should be used. Ad-
equate calcium is important for reducing
the severity of blossom-end rot. Research
shows that a Mehlich-1 (double-acid) index
of 300 to 350 ppm Ca would be indicative
of adequate soil-Ca. On limestone soils,
add 30-40 pounds per acre of magnesium
in the basic fertilizer mix. It is best to ap-
ply lime several months prior to planting.
However, if time is short, it is better to ap-
ply lime any time before planting than not
to apply it at all. Where the pH does not
need modification, but magnesium is low,
apply magnesium sulfate or potassium-
magnesium sulfate.
Changes in soil pH may take several
weeks to occur when carbonate-based
liming materials are used (calcitic or
dolomitic limestone). Oxide-based liming
materials (quick lime -CaO- or dolomitic
quick lime -CaO, MgO-) are fast reacting
and rapidly increase soil pH. Yet, despite
these advantages, oxide-based liming
materials are more expensive than the
traditional liming materials,and therefore
are not routinely used.
The increase in pH induced by liming
materials is not due to the presence of
calcium or magnesium. Instead, it is the
carbonate (CO3) and oxide (0) part of
CaCO3 and CaO, respectively, that raises
the pH. Through several chemical reac-
tions that occur in the soil, carbonates and
oxides release OH- ions that combine with
H+ to produce water. As large amounts of
H+ react, the pH rises. A large fraction of
the Ca and/or Mg in the liming materials
gets into solution and binds to the sites
that are freed by H+ that have reacted
with OH-.

Blossom-End Rot. Growers may have
problems with blossom-end-rot, espe-
cially on the first or second fruit clusters.
Blossom-end rot (BER) is a Ca deficiency in
the fruit, but is often more related to plant
water stress than to Ca concentrations in
the soil. This is because Ca movement into
the plant occurs with the water stream
(transpiration). Thus,Ca moves preferen-
tially to the leaves. As a maturing fruit is

not a transpiring organ, most of the Ca is
deposited during early fruit growth.
Once BER symptoms develop on a
tomato fruit,they cannot be alleviated
on this fruit. Because of the physiologi-
cal role of Ca in the middle lamella of cell
walls, BER is a structural and irreversible
disorder. Yet, the Ca nutrition of the plant
can be altered so that the new fruits
are not affected. BER is most effectively
controlled by attention to irrigation and
fertilization, or by using a calcium source
such as calcium nitrate when soil Ca is
low. Maintaining adequate and uniform
amounts of moisture in the soil are also
keys to reducing BER potential.
Factors that impair the ability of tomato
plants to obtain water will increase the
risk of BER.These factors include damaged
roots from flooding, mechanical damage
or nematodes, clogged drip emitters, inad-
equate water applications,alternating dry-
wet periods,and even prolonged overcast
periods. Other causes for BER include high
fertilizer rates, especially potassium and
Calcium levels in the soil should be ad-
equate when the Mehlich-1 index is 300 to
350 ppm,or above. In these cases,added
gypsum (calcium sulfate) is unlikely to
reduce BER. Foliar sprays of Ca are unlikely
to reduce BER because Ca does not move
out of the leaves to the fruit.
Gray Wall. Blotchy ripening (also called
gray wall) of tomatoes is characterized by
white or yellow blotches that appear on
the surface of ripening tomato fruits,while
the tissue inside remains hard.The af-
fected area is usually on the upper portion
of the fruit. The etiology of this disorder
has not been fully established, but it is
often associated with high N and/or low
K,and aggravated by excessive amount of
N. This disorder may be at times confused
with symptoms produced by the tobacco
mosaic virus. Gray wall is cultivar specific
and appears more frequently on older
cultivars. The incidence of gray wall is less
with drip irrigation where small amounts
of nutrients are injected frequently,than
with systems where all the fertilizer is ap-
plied pre-plant.
Micronutrients. For acidic sandy soils cul-

tivated for the first time ("new ground"), or
sandy soils where a proven need exists,a
general guide for fertilization is the addi-
tion of micronutrients (in elemental Ibs/A)
manganese -3, copper -2, iron -5,zinc -2,
boron -2,and molybdenum -0.02. Micro-
nutrients may be supplied from oxides or
sulfates. Growers using micronutrient-
containing fungicides need to consider
these sources when calculating fertilizer
micronutrient needs.
Properly diagnosed micronutrient de-
ficiencies can often be corrected by foliar
applications of the specific micronutrient.
For most micronutrients,a very fine line
exists between sufficiency and toxicity.
Foliar application of major nutrients (ni-
trogen, phosphorus,or potassium) has not
been shown to be beneficial where proper
soil fertility is present.

Mulch Production with Seepage Irriga-
tion. Under this system,the crop may be
supplied with all of its soil requirements
before the mulch is applied (Table 1). It is
difficult to correct a deficiency after mulch
application,although a liquid fertilizer
injection wheel can facilitate sidedressing
through the mulch. The injection wheel
will also be useful for replacing fertilizer
under the used plastic mulch for double-
cropping systems. A general sequence of
operations for the full-bed plastic mulch
system is:
1. Land preparation, including develop-
ment of irrigation and drainage systems,
and liming of the soil, if needed.
2. Application of"cold" mix comprised of
10% to 20% of the total N and potassium
seasonal requirements and all of the need-
ed phosphorus and micronutrients. The
cold mix can be broadcast over the entire
area prior to bedding and then incorpo-
rated. During bedding,the fertilizer will be
gathered into the bed area.An alternative
is to use the"modified broadcast"tech-
nique for systems with wide bed spacings.
Use of modified broadcast or banding
techniques can increase phosphorus and
micronutrient efficiencies, especially on
alkaline (basic) soils.
3. Formation of beds, incorporation of


herbicide,and application of mole cricket
4.The remaining 80% to 90% of the
N and potassium is placed in one or two
narrow bands 9 to 10 inches to each side
of the plant row in furrows. This"hot mix"
fertilizer should be placed deep enough
in the grooves for it to be in contact with
moist bed soil. Bed presses are modified
to provide the groove. Only water-soluble
nutrient sources should be used for the
banded fertilizer. A mixture of potassium
nitrate (or potassium sulfate or potassium
chloride),calcium nitrate,and ammonium
nitrate has proven successful. Research
has shown that it is best to broadcast
incorporate controlled-release fertilizers
(CRF) in the bed with bottom mix than in
the hot bands.
5. Fumigation, pressing of beds,and
mulching.This should be done in one
operation, if possible. Be sure that the
mulching machine seals the edges of the
mulch adequately with soil to prevent
fumigant escape.
Water management with the seep
irrigation system is critical to successful
crops. Use water-table monitoring devices
and tensiometers orTDRs in the root zone
to help provide an adequate water table
but no higher than required for optimum
moisture. It is recommended to limit
fluctuations in water table depth since this
can lead to increased leaching losses of
plant nutrients. An in-depth description
of soil moisture devices may be found in
Muhoz-Carpena (2004).
Mulched Production with Drip Irriga-
tion. Where drip irrigation is used,drip
tape or tubes should be laid 1 to 2 inches
below the bed soil surface prior to mulch-
ing.This placement helps protect tubes
from mice and cricket damage. The drip
system is an excellent tool with which to
fertilize tomato. Where drip irrigation is
used,apply all phosphorus and micronu-
trients,and 20 percent to 40 percent of
total nitrogen and potassium preplant
in the bed. Apply the remaining N and
potassium through the drip system in
increments as the crop develops.
Successful crops have resulted where

the total amounts of N and K20 were nitrogen sources may be used to supply a
applied through the drip system. Some portion of the nitrogen requirement. One-
growers find this method helpful where third of the total required nitrogen can be
they have had problems with soluble- supplied from sulfur-coated urea (SCU),
salt burn. This approach would be most isobutylidene diurea (IBDU),or polymer-
likely to work on soils with relatively high coated urea (PCU) fertilizers incorporated
organic matter and some residual potas- in the bed. Nitrogen from natural organic
sium. However, it is important to begin and most controlled-release materials
with rather high rates of N and K20 to is initially in the ammoniacal form, but
ensure young transplants are established is rapidly converted into nitrate by soil
quickly. In most situations,some preplant microorganisms.
N and Kfertilizers are needed. Normal superphosphate and triple
Suggested schedules for nutrient superphosphate are recommended for
injections have been successful in both phosphorus needs. Both contribute
research and commercial situations, but calcium and normal superphosphate
might need slight modifications based contributes sulfur.
on potassium soil-test indices and grower All sources of potassium can be used for
experience (Table 1). tomato. Potassium sulfate, sodium-potas-
sium nitrate, potassium nitrate, potassium
SOURCES OF N-P205-K20. chloride,monopotassium phosphate,
About 30% to 50% of the total applied N and potassium-magnesium sulfate are all
should be in the nitrate form for soil treat- good K sources. If the soil test predicted
ed with multi-purpose fumigants and for amounts of K20 are applied, then there
plantings in cool soil. Controlled-release should be no concern for the K source or
TABLE 2. Deficient, adequate, and excessive nutrient concentrations for tomato
[most-recently-matured (MRM) leaf (blade plus petiole)].
Stage of Growth N P K Ca Mg S Fe Mn Zn B Cu Mo
............... % ............. .. ...... ppm ...........
Tomato MRM 5-leaf Deficient <3.0 0.3 3.0 1.0 0.3 0.3 40 30 25 20 5 0.2
leaf stage
Adequate 3.0 0.3 3.0 1.0 0.3 0.3 40 30 25 20 5 0.2
range 5.0 0.6 5.0 2.0 0.5 0.8 100 100 40 40 15 0.6
High >5.0 0.6 5.0 2.0 0.5 0.8 100 100 40 40 15 0.6
MRM First Deficient <2.8 0.2 2.5 1.0 0.3 0.3 40 30 25 20 5 0.2
leaf flower
Adequate 2.8 0.2 2.5 1.0 0.3 0.3 40 30 25 20 5 0.2
range 4.0 0.4 4.0 2.0 0.5 0.8 100 100 40 40 15 0.6
High >4.0 0.4 4.0 2.0 0.5 0.8 100 100 40 40 15 0.6
Toxic (>) 1500 300 250
MRM Early Deficient <2.5 0.2 2.5 1.0 0.25 0.3 40 30 20 20 5 0.2
leaf fruit set
Adequate 2.5 0.2 2.5 1.0 0.25 0.3 40 30 20 20 5 0.2
range 4.0 0.4 4.0 2.0 0.5 0.6 100 100 40 40 10 0.6
High >4.0 0.4 4.0 2.0 0.5 0.6 100 100 40 40 15 0.6
Toxic (>) 250
Tomato MRM First ripe Deficient <2.0 0.2 2.0 1.0 0.25 0.3 40 30 20 20 5 0.2
leaf fruit
Adequate 2.0 0.2 2.0 1.0 0.25 0.3 40 30 20 20 5 0.2
range 3.5 0.4 4.0 2.0 0.5 0.6 100 100 40 40 10 0.6
High >3.5 0.4 4.0 2.0 0.5 0.6 100 100 40 40 10 0.6
MRM During Deficient <2.0 0.2 1.5 1.0 0.25 0.3 40 30 20 20 5 0.2
leaf harvest
Adequate 2.0 0.2 1.5 1.0 0.25 0.3 40 30 20 20 5 0.5
range 3.0 0.4 2.5 2.0 0.5 0.6 100 100 40 40 10 0.6
High <2.0 0.2 1.5 1.0 0.25 0.3 40 30 20 20 5 0.2



its associated salt index.

While routine soil testing is essential in
designing a fertilizer program,sap tests
and/or tissue analyses reveal the actual
nutritional status of the plant. Therefore
these tools complement each other, rather
than replace one another.
When drip irrigation is used,analysis
of tomato leaves for mineral nutrient
content (Table 2) or quick sap test (Table
3) can help guide a fertilizer management
program during the growing season or
assist in diagnosis of a suspected nutrient
For both nutrient monitoring tools,
the quality and reliability of the mea-
surements are directly related with the
quality of the sample. A leaf sample
should contain at least 20 most recently,
fully developed, healthy leaves. Select
representative plants, from representative
areas in the field.

In practice, supplemental fertilizer applica-
tions allow vegetable growers to numeri-
cally apply fertilizer rates higher than the
standard UF/IFAS recommended rates
when growing conditions require doing
so. Applying additional fertilizer under the
three circumstances described in Table
1 (leaching rain,'low'foliar content,and
extended harvest season) is part of the
current UF/IFAS fertilizer recommenda-
tions and nutrient BMPs.

Based on the growing situation and the
level of adoption of the tools and tech-
niques described above,different levels
of nutrient management exist for tomato
production in Florida. Successful produc-
tion and nutrient BMPs requires manage-
ment levels of 3 or above (Table 4).*

Cantliffe, D, P. Gilreath, D. Haman, C. Hutchinson,
Y. Li, G. McAvoy, K. Migliaccio, T Olczyk, S. Olson, D.

Parmenter, B. Santos, S. Shukla, E. Simonne, C. Stanley,
andA. Whidden.2009. Review ofnutrientmanage-
ment systems for Florida vegetable producers. EDIS
HS1156, http://edis.ifas.ufl.edu/HS 1156.

Florida Department ofAgriculture and Consumer
Services. 2005. Florida Vegetable andAgronomic Crop
Water Quality and Quantity BMP Manual.

Gazula, A., E.Simonne and B. Boman. 2007. Update
and outlook for2007 ofFlorida=s BMP program for
vegetable crops, EDIS Doc.367, http://edis.ifas.ufl.

Hochmuth, G., D. Maynard, C. Vavrina, E. Hanlon, and
E.Simonne.2004. Plant tissue analysis and interpreta-
tion for vegetable crops in Florida. EDIS http://edis.

Munoz-Carpena, R. 2004. Field devices for monitoring
soil water content. EDIS. Bul 343. http://edis.ifas.ufl.

Olson, S.M., W.M. Stall, G.E. Vallad, S.E. Webb, T.G.
Taylor, S.A. Smith, E.H. Simonne, E. McAvoy, and B.M.
Santos. 2009. Tomato production in Florida, pp. 291-
312. In:S.M.Olson and E.Simonne (Eds.) 2009-2010
Vegetable Production Handbook for Florida, Vance
Pub., Lenexa, KS.

Simonne, E.H. and GJ. Hochmuth. 2009. Soil and
fertilizer management for vegetable production in
Florida, pp. 3-15. In:S.M. Olson and E. Simonne (Eds.)
2009-2010 Vegetable Production Handbook for
Florida, Vance Pub., Lenexa, KS.

Simonne, E., D. Studstill, B. Hochmuth, T. Olczyk, M.
Dukes, R. Munoz-Carpena, and Y. Li. 2002. Drip irriga-
tion: The BMP era -An integrated approach to water
and fertilizer management in Florida, EDIS HS917,
http://edis.ifas.ufl.edu/HS 172.

Studstill, D., E. Simonne, R. Hochmuth, and T. Olczyk.
2006. Calibrating sap-testing meters. EDISHS 1074,

TABLE 3. Recommended nitrate-N and K
concentrations in fresh petiole sap for round

Sap concentration (ppm)
Stage of growth N03-N K
First buds 1000-1200 3500-4000
First open flowers 600-800 3500-4000
Fruits one-inch diameter 400-600 3000-3500
Fruits two-inch diameter 400-600 3000-3500
First harvest 300-400 2500-3000
Second harvest 200-400 2000-2500

TABLE 4. Progressive levels of nutrient man-
agement for tomato production.'
Nutrient Management Description
Level Rating
0 None Guessing
1 Very low Soil testing and still
2 Low Soil testing and
implementing "a"
3 Intermediate Soil testing, under-
standing IFAS recom-
mendations, and cor-
rectly implementing
4 Advanced Soil testing, under-
standing IFAS recom-
mendations, correctly
implementing them,
and monitoring crop
nutritional status
5 Recommended Soil testing, under-
standing IFAS recom-
mendations, correctly
implementing them,
monitoring crop
nutritional status, and
practice year-round
nutrient management
and/or following BMPs
(including one of the
recommended irriga-
tion scheduling




William M. Stall, University of Florida/IFAS, Horticultural Sciences Dept., Gainesville, FL, wmstall@ufl.edu

Although weed control has always been
an important component of tomato produc-
tion, its importance has increased with the
introduction of the sweet potato whitefly
and development of the associated irregular
ripening problem. Increased incidence
of several viral disorders of tomatoes also
reinforces the need for good weed control.
Common weeds,such as the difficult-to-
control nightshade,and volunteer tomatoes
(considered a weed in this context) are hosts
to many tomato pests, including sweet
potato whitefly, bacterial spot,and viruses.
Control of these pests is often tied,at least in
part,to control of weed hosts. Most growers
concentrate on weed control in row middles;
however, peripheral areas of the farm should
not be neglected. Weed hosts and pests
may flourish in these areas and serve as
reservoirs for re-infestation of tomatoes by
various pests. Thus,it is important for grow-
ers to think in terms of weed management
on the entire farm, not just the actual crop
Total farm weed management is more
complex than row middle weed control
because several different sites and possible
herbicide label restrictions are involved.
Often weed species in row middles differ
from those on the rest of the farm,and this
might dictate different approaches. Sites
other than row middles include roadways,
fallow fields,equipment parking areas,well
and pump areas,fence rows and associated
perimeter areas,and ditches.
Disking is probably the least expensive
weed control procedure for fallow fields.
Where weed growth is mostly grasses,clean
cultivation is not as important as in fields
infested with nightshade and other disease
and insect hosts. In the latter situation,
weed growth should be kept to a minimum
throughout the year. If cover crops are
planted,they should be plants which do
not serve as hosts for tomato diseases and
insects. Some perimeter areas are easily
disked, but berms and field ditches are not
and some form of chemical weed control
may have to be used on these areas. We are

not advocating bare ground on the farm
as this can lead to other serious problems,
such as soil erosion and sand blasting of
plants; however,where undesirable plants
exist, some control should be practiced, if
practical,and replacement of undesirable
species with less troublesome ones, such as
bahiagrass, might be worthwhile.
Certainly fence rows and areas around
buildings and pumps should be kept weed-
free, if for no other reason than safety. Her-
bicides can be applied in these situations,
provided care is exercised to keep them
from drifting onto the tomato crop.
Field ditches and canals present special
considerations because many herbicides are
not labeled for use on aquatic sites. Where
herbicidal spray may contact water and be
in close proximity to tomato plants,for all
practical purposes,growers probably would
be wise to use Diquat only. On canals where
drift onto the crop is not a problem and
weeds are more woody,Rodeo,a systemic
herbicide, could be used. Other herbicide
possibilities exist,as listed in Table 1. Grow-
ers are cautioned against using Arsenal on
tomato farms because tomatoes are very
sensitive to this herbicide. Particular caution
should be exercised if Arsenal is used on
seepage irrigated farms because it has been
observed to move in some situations.
Use of rye as a windbreak has become a
common practice in the spring; however,in
some cases,adverse effects have resulted. If
undesirable insects such as thrips build up
on the rye,contact herbicide can be applied
to kill it and eliminate it as a host,yet the
remaining stubble could continue serving as
a windbreak.
The greatest row middle weed problem
confronting the tomato industry today is
nightshade. Nightshade has developed
varying levels of resistance to some post-
emergent herbicides in different areas of the
state. Best control with post-emergence (di-
rected) contact herbicides is obtained when
the nightshade is 4 to 6 inches tall, rapidly
growing and not stressed. Two applications
in about 50 gallons per acre using a good

surfactant are usually necessary.
With post-directed contact herbicides,
several studies have shown that volumes
above 60 gallons per acre will actually dilute
the herbicides and therefore reduce efficacy.
Good leaf coverage can be obtained with
volumes of 50 gallons or less per acre. A
good surfactant can do more to improve
the wetting capability of a spray than can in-
creasing the water volume. Many adjuvants
are available commercially. Some adjuvants
contain more active ingredient than others
and herbicide labels may specify a minimum
active ingredient rate for the adjuvant in
the spray mix. Before selecting an adjuvant,
refer to the herbicide label to determine the
adjuvant specifications.

Additionally important is good field sanita-
tion with regard to crop residue. Rapid
and thorough destruction of tomato vines
at the end of the season always has been
promoted; however, this practice takes on
new importance with the sweet potato
whitefly. Good canopy penetration of
pesticidal sprays is difficult with conven-
tional hydraulic sprayers once the tomato
plant develops a vigorous bush due to foliar
interception of spray droplets. The sweet
potato whitefly population on commercial
farms was observed to begin a dramatic,
rapid increase about the time of first harvest
in the spring of 1989. This increase appears
to continue until tomato vines are killed. It
is believed this increase is due,in part,to
coverage and penetration. Thus, it would
be wise for growers to continue spraying for
whiteflies until the crop is destroyed and to
destroy the crop as soon as possible with
the fastest means available. Gramoxone
Inteon and Firestorm are labeled for post-
harvest desiccation of tomato vines. Follow
the label directions.
The importance of rapid vine destruction
cannot be overstressed. Merely turning off
the irrigation and allowing the crop to die
will not do; application of a desiccant fol-
lowed by burning is the prudent course. *



Herbicide Labeled Crops Time of Application to Crop Rate (Ibs. AI./Acre)
Mineral Soils Muck Soils
Carfentrazone (Aim) Tomato Preplant Directed-hooded Row-middles 0.031 0.031
Remarks: Aim may be applied as a preplant burndown treatment and/or as a post-directed hooded application to row middles for the bumdown of emerged broadleaf weeds. May be tank mixed with other
registered herbicides. May be applied at up to 2 oz (0.031 Ib ai). Use a quality spray adjuvant such as crop oil concentrate (COC) or non-ionic surfactant at recommended rates.
Clethodim (Select 2 EC)
(Arrow) (SelectMax) Tomatoes Postemergence 0.9-.25
Remarks: Postemergence control of actively growing annual grasses. Apply at 6-16 fl oz/acre. Use high rate under heavy grass pressure and/or when grasses are at maximum height. Always use a crop
oil concentrate at 1% v/v in the finished spray volume, or a non-ionic Surfactant with SelectMAX. Do not apply within 20 days of tomato harvest.
DCPA (Dacthal W-75) Established tomatoes Posttransplanting after crop establishment (non-mulched) 6.0-8.0
Remarks: Controls germinating annuals. Apply to weed-free soil 6 to 8 weeks after crop is established and growing rapidly or to moist soil in row middles after crop establishment. Note label precautions
against replanting non-registered crops within 8 months.
EPTC (Eptam 7E) Tomatoes Pretransplant 2.62-3.5
Remarks: Labeled for transplanted tomatoes grown on plastic mulch. Apply 3-4 pints/A to the bed top and shoulders immediately prior to the installation of the mulch. Do not transplant the tomato plants
for a minimum of 14 days following the application. A 24c special local needs label for Florida.
Flumloxazin Fruiting Vegetables Directed Row-middles
(Chateau) Tomatoes 0.125
Remarks: Chateau may be applied up to 4 oz product/application to row middles of raised plastic mulched beds that are at least 4 inches higher than the treated row middle and the mulched bed must
be a minimum of a 24-inch bed width. Do not apply after crops are transplanted. All applications must be made with shielded or hooded equipment. For control of emerged weeds, a bum down herbicide
may be tank-mixed. Label is a Third-Party registration (TPR, Inc.). Use without a signed authorization and waiver of liability is a misuse of the product.
Glyphosate (Roundup, Tomatoes Chemical fallow Preplant, Preemergence, 0.3-1.0
Durango, Touchdown, Pretransplant
Remarks: Roundup, Glyphomax and Touchdown have several formulations. Check the label of each for specific labeling directions.
Halosulfuron (Sandea) Tomatoes Pretransplant Postemergence Row middles 0.024-0.036
Remarks: A total of 2 applications of Sandea may be applied as either one pre-transplant soil surface treatment at 0.5-0.75 oz. product; one over-the-top application 14 days after transplanting at 0.5-
0.75 oz. product; and/or postemergence applications(s) of up to 1 oz. product (0.047 Ib ai) to row middles. A 30-day PHI will be observed. For postemergence and row middle applications, a surfactant
should be added to the spray mix.
Lactofen (Cobra) Fruiting vegetables Row middles 0.25-0.5
Remarks: Third Party label for use pre-transplant or post transplant shielded or hooded to row middles. Apply 16 to 32 fluid oz per acre. A minimum of 24fl oz is required for residual control. Add a COC
or non-ionic surfactant for control of emerged weeds. 1 pre and 1 post application may be made per growing season. Cobra contacting green foliage or fruit can cause excessive injury. Drift of Cobra
treated soil particles onto plants can cause contact injury. Do not apply within 30 days of harvest. The supplemental label must be in the possession of the user at the time of application.
S-Metolachlor Tomatoes Pretransplant- Row middles 1.0-1.3
(Dual Magnum)
Remarks: Apply Dual Magnum preplant non-incorporated to the top of a pressed bed as the last step prior to laying plastic. May also be used to treat row middles. Label rates are 1.0-1.33 pts/A if
organic matter is less than 3%. Research has shown that the 1.33 pt may be too high in some Florida soils except in row middles. Good results have been seen at 0.6 pts to 1.0 pints especially in tank
mix situations under mulch. Use on a trial basis.
Metribuzin Tomatoes Postemergence Posttransplanting 0.25 -0.5
(Sencor DF) (Sencor 4) after establishment
Remarks: Controls small emerged weeds after transplants are established or when direct-seeded plants reach 5 to 6 true leaf stage. Apply in single or multiple applications with a minimum of 14 days
between treatments and a maximum of 1.0 Ib ai/acre within a crop season. Avoid applications for 3 days following cool, wet or cloudy weather to reduce possible crop injury.
Metribuzin Tomatoes Directed spray in row middles 0.25 -1.0
(Sencor DF) (Sencor 4)
Remarks: Apply in single or multiple applications with a minimum of 14 days between treatments and maximum of 1.0 Ib ai/acre within crop season. Avoid applications for 3 days following cool, wet or
cloudy weather to reduce possible crop injury. Label states control of many annual grasses and broadleaf weeds including, lambsquarter, fall panicum, Amaranthus sp., Florida pusley, common ragweed,
sicklepod, and spotted spurge.
Napropamide Tomatoes Preplant incorporated 1.0-2.0
(Devnnol 50DF)
Remarks: Apply to well worked soil that is dry enough to permit thorough incorporation to a depth of 1 to 2 inches. Incorporate same day as applied. For direct-seeded or transplanted tomatoes.
Napropamide Tomatoes Surface treatment 2.0
(Devnnol 50DF)
Remarks: Controls germinating annuals. Apply to bed tops after bedding but before plastic application. Rainfall or overhead-irrigate sufficient to wet soil 1 inch in depth should follow treatment within 24
hours. May be applied to row middles between mulched beds. A special Local Needs 24(c) Label for Florida. Label states control of weeds including Texas panicum, pigweed, purslane, Florida pusley, and
Oxyfluorfen (Goal 2XL) Tomatoes Fallow bed 0.25-0.5
Remarks: Must have a 30-day treatment-planting interval for transplanted tomatoes. Apply as a preemergence broadcast to preformed beds or banded treatment at 1-2 pt/A or 1/2 to 1 pt/A for Goalten-
der Mulch may be applied any time during the 30-day interval.
Paraquat (Gramoxone Tomatoes Premergence; Pretransplant 0.62-0.94
Inteon) (Firestorm)
Remarks: Controls emerged weeds. Use a non- ionic spreader and thoroughly wet weed foliage.
Paraquat (Gramoxone Tomatoes Post directed spray in row middles 0.47
Inteon) (Firestorm)
Remarks: Controls emerged weeds. Direct spray over emerged weeds 1 to 6 inches tall in row middles between mulched beds. Use a non-ionic spreader Use low pressure and shields to control drift. Do
not apply more than 3 times per season.
Paraquat (Gramoxone Tomatoes Postharvest desiccation 0.62-0.93 0.46-0.62
Inteon) (Firestorm)
Remarks: Broadcast spray over the top of plants after last harvest. Gramoxone label states use of 2-3 pts. Use a non-ionic surfactant at 1 pt/100 gals to 1 qt/100 gals spray solution. Thorough cover-
age is required to ensure maximum herbicide burndown. Do not use treated crop for human or animal consumption.
Pelargonic Acid Fruiting vegetables Preplant Preemergence Directed-shielded 3-10% v/v
(Scythe) (tomato)
Remarks: Product is a contact, nonselective, follar applied herbicide. There is no residual control. May be tank mixed with several soil residual compounds. Consult the label for rates. Has a greenhouse
and growth structure label.
Pendimethalin Tomatoes Post-directed Row Middles 0.0475-1.43
Prowl H ,0
Remarks: May be applied pre-transplant but not under mulch. May be applied at 1.0 to 3 pts/A to row middles. Do not apply within 70 days of harvest.
Rimsulfuron (Matrix) Tomatoes Posttransplant and directed-row middles 0.25-0.5 oz
Remarks: Matrix may be applied preemergence (seeded), postemergence, posttransplant and applied directed to row middles. May be applied at 1-2 oz. product (0.25-0.5 oz ai) in single or sequential
applications. A maximum of 4 oz. product per acre per year may be applied. For post (weed) applications, use a non-ionic surfactant at a rate of 0.25% v/v. for preemergence (weed) control, Matrix must
be activated in the soil with sprinkler irrigation or rainfall. Check crop rotational guidelines on label.
Sethoxydim (Poast) Tomatoes Postemergence 0.188 -0.28
Remarks: Controls actively growing grass weeds. A total of 4 1/2 pts. product per acre may be applied in one season. Do not apply within 20 days of harvest. Apply in 5 to 20 gallons of water adding 2
pts. of crop oil concentrate per acre. Unsatisfactory results may occur if applied to grasses under stress. Use 0.188 Ib ai (1 pt.) to seedling grasses and up to 0.28 Ib ai (1 1/2 pts.) to perennial grasses
emerging from rhizomes etc. Consult label for grass species and growth stage for best control.
Trfloxysulfuron Tomatoes (transplanted) Post directed 0.007-0.014
Remarks: Envoke can be applied at 0.1 to 0.2 oz product/A post-directed to transplanted tomatoes for control of nutsedge, morning-glory, pigweeds and other weeds listed on the label. Applications
should be made prior to fruit set and at least 45 days prior to harvest. A non-ionic surfactant should be added to the spray mix.
Trfluralin (Treflan HFP) Tomatoes Pretransplant incorporated 0.5 (Treflan TR-10) (except Dade County)
(Tnfluralin 4EC)
Remarks: Controls germinating annuals. Incorporate 4 inches or less within 8 hours of application. Results in Florida are erratic on soils with low organic matter and clay contents. Note label precautions
against planting non-crops within 5 months. Do not apply after transplanting.




Gary E. Vallad, University of Florida/IFAS, GCREC, Wimauma, FL, gvallad@ufl.edu


Max. Rate/ Pertinent
Fungicide Acre/ Min. Days Diseases or
Chemical group' Applic. Season to Harvest Pathogens Remarks2
fix copper compounds (many brands available: Badge SC, M1 1 Anthracnose Mancozeb or maneb enhances bactericidal
Basic Copper 50W HB, Basic Copper 53, COCS WDG, Champ Bacterial speck effect of fix copper compounds. See label for
DP, Champ F2 FL, Champ WG, Champion WP, COC DF, COC Bacterial spot details.
WP, Copper Count N, Cuprofix Ultra 40D, Kentan DF, Kocide Early blight
3000, Kocide 2000, Kocide DF, Nordox, Nordox 75WG, Nu Grey leaf mold
Cop 50WP, Nu Cop 3L, Nu Cop 50DF, Nu Cop HB) Grey leaf spot
Late blight
Septoria leaf spot
sulfur (many brands available: Cosavet DF, Kumulus DF, Micro M2 1 Powdery mildew Follow label closely, it may cause phytotoxicity.
Sulf, Microfine Sulfur, Microthiol Disperss, Sulfur 6L, Sulfur
90W, Super Six, That Flowable Sulfur, Tiolux Jet, Thiosperse
80%, Wettable Sulfur, Wettable Sulfur 92, Yellow Jacket Dust-
ing Sulfur, Yellow Jacket Wettable Sulfur)
maneb (many brands available: Maneb 75DF, Maneb 80WP, M3 2.4 qts. 16.8 5 Early blight See label for details
Manex, ) qts. Late blight
Gray leaf spot
mancozeb (many brands available: Dithane DF, Dithane F45, M3 3 Ibs. 22.4 5 Bacterial spot'
Dithane M45, Manzate, Manzate Pro-Stik, Penncozeb 4FL, Ibs. Anthracnose
Penncozeb 75DF, Penncozeb 80WP) Leaf mold
Septoria leaf spot
Ziram (ziram) M3 4 Ibs 24 Ibs 7 Anthracnose Do not use on cherry tomatoes. See label for
Early blight details.
Septoria leaf spot
ManKocide (mancozeb + copper hydroxide) M3 / M1 5 Ibs. 112 5 Bacterial spot See label
Ibs. Bacterial speck
Late blight
Early blight
Gray leaf spot
chlorothalonil (many brands available: Bravo Ultrex, Bravo M5 0 Early blight Use higher rates at fruit set and lower rates
Weather Stik, Bravo Zn, Chloronil 720, Echo 720, Echo 90 Late blight before fruit set, see label
DF, Echo Zn, Equus 500 Zn, Equus 720 SST, Equus DF, Initiate Gray leaf spot
720) Leaf mold
Target spot Botrytis
fruit rot
Alpro Exotherm Termil (20 % chlorothalonil) M5 1 can 7 Botrytis Greenhouse use only. Allow can to remain
/ 1000 Leaf mold overnight and then ventilate. Do not use when
sq. ft. Late blight greenhouse temperature is above 75 F. See
Early blight label for details.
Gray leaf spot
Target spot
Rally 40WSP, Nova 40 W (myclobutanil) 3 4 oz. 1.25 0 Powdery mildew Note that a 30 day plant back restriction ex-
Ibs. ists, see label
Ridomil Gold EC (mefenoxam) 4 2 pts. 3 pts 28 Pythium diseases See label for details
/ trtd. / trtd.
acre acre
Ultra Flourish (mefenoxam) 4 2 qts 3 qts Pythium and See label for details
Phytophthora rots
Ridomil MZ 68 WP (mefenoxam + mancozeb) 4 / M3 2.5 Ibs. 7.5 5 Late blight Limit is 3 appl./crop, see label
Ridomil Gold Copper 64.8 W (mefenoxam + copper hydrox- 4 / M1 2 Ibs. 14 Late blight Limit is 3 appl. /crop. Tank mix with maneb or
ide) mancozeb fungicide, see label
Ridomil Gold Bravo 76.4 W (chlorothalonil +mefenoxam) 4 / M5 3 Ibs. 12 Ibs 14 Early blight Limit is 4 appl./crop, see label
Late blight
Gray leaf spot
Target Spot
Endura (boscalid) 7 12.5 oz 25 oz. 0 Target spot Alternate with non-FRAC code 7 fungicides,
(Corynespora see label
Early Blight
(Alternaria solani)
Scala SC (pyrimethanil) 9 7 fl oz 35 fl 1 Early blight Use only in a tank mix with another effective
oz Botrytis fungicide
(non FRAC code 9); 30 day plant back with off
label crops; see label
Amistar 80 DF (azoxystrobin) 11 2 oz 12 oz 0 Early blight Limit is 6 appl/crop. Must alternate or tank
Late blight mix with a fungicide from a different FRAC
Sclerotinia group, see label.
Powdery mildew
Target spot
Buckeye rot
Quadris (azoxystrobin) 11 6.2 37.2. 0
fl.oz. fl.oz.



Cabrio 2.09 F (pyraclostro-bin) 11 16floz 96fl 0 Early blight Only 2 sequential appl. allowed. Limit is 6 appl/
oz Late blight crop. Must alternate or tank mix with a fungi-
Sclerotinia cide from a different FRAC group, see label.
Powdery mildew
Target spot
Buckeye rot
Flint (trifloxystro-bin) 11 4 oz 16 oz 3 Early blight Limit is 5 appl/crop. Must alternate or tank mix
Late blight with a fungicide from a different FRAC group,
Gray leaf spot see label.
Evito (fluoxastrobin) 11 5.7 fl oz 22.8 fl 3 Early blight Limit is 4 appl/crop. Must alternate or tank mix
oz Late blight with a fungicide from a different FRAC group,
Southern blight see label.
Target spot
Reason 500SC (fenamidone) 11 8.2 oz 24.6 14 Early blight Late See label for details
Ib blight Septoria
leaf spot
Tanos (famoxadone + cymoxanil) 11 / 27 8 oz 72 oz 3 Late blight Do not alternate or tank mix with other FRAC
Target spot group 11 fungicides. See label for details
Bacterial spot (suppres-
Terramaster 4EC (etridiazole) 14 7 fl oz 27.4 fl 3 Pythium and Phytoph- Greenhouse use only. See label for details
oz thora root rots
Blocker 4F Terraclor 75 WP (PCNB) 14 See See Southern blight (Sclero- See label for
Label Label tium rolfsii) application type and restrictions
Botran 75 W (dichloran) 14 1 lb. 4 Ibs. 10 Botrytis Greenhouse use only. Limit is 4 applications.
Seedlings or newly set transplants may be
injured, see label
Ranman (cyazofamid) 21 2.1- 16 oz 0 Late Blight Limit is 6 appl./crop, see label
2.75 oz
Gavel 75DF (zoaximide + mancozeb) 22/M3 2.0 Ibs 16 Ibs 5 Buckeye rot See label
Early blight
Gray leaf spot
Late blight
Leaf mold
Agri-mycin 17 (streptomycin sulfate) 25 200 Bacterial spot See label for details. For transplant production
ppm Bacterial speck only. Many isolates are resistant to strepto-
Ag Streptomycin (streptomycin sulfate) mycin.

Fire Wall (streptomycin sulfate)
Curzate 60DF (cymoxanil) 27 5 oz 30 oz 3 Late Blight Do not use alone, see label for details
Previcur Flex (propamocarb hydrochloride) 28 1.5 7.5 5 Late blight Only in a tank mixture with chlorotalonil, maneb
pints pints or mancozeb, see label
K-phite 7LP 33 See 0 Phythophthora spp. Do not apply with
Fosphite label Pythium spp. copper-based fungicides. See label for restric-
Fungi-Phite Fusarium spp. tions and details
Helena Prophyte Rhizoctonia
Phostrol Late Blight
Topaz Powdery Mildew
(mono-and di-potassium salts of phosphorous acid)
Aliette 80 WDG (fosetyl-al) 33 5 Ibs. 20 14 Phytophthora root rot See label for warnings concerning the use of
Ibs. copper compounds.
Acrobat 50 WP (dimethomorph) 40 6.4 oz 32 oz 4 Late blight See label for details
Forum (dimethomorph) 40 6 oz 30 oz 4 Late blight Only 2 sequential appl. See label for details
Revus Top (mandipropamid + difenoconazole) 40/3 7 fl oz 28 fl 1 Anthracnose 4 apps per season; no more than 2 sequential
oz Black mold apps; do not use on varieties with mature fruit
Early blight less than 2 inches in diameter. Not labeled for
Gray leafspot transplants. See label
Late blight
Powdery mildew
Septoria leafspot
Target spot
Presidio (Fluopicolide) 43 3-4 fl 12 fl 2 Late blight 4 apps per season; no more than 2 sequential
oz oz/ Phythophthora spp. apps. 10 day spray interval; Tank mix with
per another labeled fungicide with a different mode
sea- of action; 18 month rotation with off label crops
Serenade ASO 44 See See 0 Bacterial spot Mix with copper compounds, see label.
Serenade Max label label Early Blight
Sonata (Bacillus sp.) Late Blight
Powdery mildew
Target spot
Actigard (acibenzolar-S-methyl) P 0.75 4.75 14 Bacterial spot Bacterial Do not use highest labeled rate in early sprays
oz. oz speck Tomato spotted to avoid a delayed onset of harvest. See label
wilt-a viral disease for details.
(use in combination of
UV-reflective mulch and
vector thrips specific
AgriPhage (bacteriophage) NC 2 pts 0 Bacterial spot See label for details.
Bacterial speck


Oxidate (hydrogen peroxide) NC 1:100 0 Anthracnose Bacte- See label for details.
dilution rial speck Bacterial spot
Early blight
Late blight
Powdery mildew Rhizoc-
tonia fruit rot
Amicarb 100 NC See 0 Powdery mildew See label for details.
Kaligreen label
Milstop (Potassium bicarbonate)
JMS Stylet-Oil (paraffinic oil) NC 3 qts. Potato Virus Y See label for restrictions and use (e.g. use of
Tobacco Etch Virus 400 psi spray pressure)
Cucumber Mosaic Virus



Susan Webb, University of Florida/IFAS, Entomology and Nematology Dept., Gainesville, FL, sewe@ufl.edu

Trade Name Rate REI Days to Insects MOA Notes
(CommonName) (product/acre) (hours) Harvest Code1

Acramite-50WS (bifenazate) 0.75-1.0 Ib 12 3 twospotted spider mite un One application per season.
Actara (thiamethoxam) 2.0-5.5 oz 12 0 aphids,flea beetles, leafhoppers, stinkbugs, 4A Maximum of 11 oz/acres per season. Do not usefol-
whiteflies lowing a soil application of a Group 4A insecticide.
Admire Pro (imidacloprid) 7-10.5fl oz 12 21 aphids, Colorado potato beetle,flea beetles, 4A Most effective if applied to soil at transplanting. Limit-
leafhoppers, thrips (foliar feeding thrips only), ed to 24 oz/acre. Admire Pro limited to 10.5 fl ozlacre.
Admire Pro (imidacloprid) 0.6fl oz/1,000 plants 12 0 (soil) aphids,whiteflies 4A Greenhouse Use:1 application to mature plants, see
label for cautions.
Admire Pro (imidacloprid) 0.44floz/10,000plants 12 21 aphids,whiteflies 4A Planthouse: 1 application. See label.
AgreeWG (Bacillus thuringiensis 0.5-2.0 Ib 4 0 armyworms, hornworms, loopers, tomato 11 Apply when larvae are small for best control. Can be
subspecies aizawai) fruitworm used in greenhouse. OMRI-listed2.
*Agri Mek 0.15EC (abamectin) 8-16 fl oz 12 7 broad mite,Colorado potato beetle, Liriomyza 6 Do not make more than 2 sequential applications. Do
leafminers, spider mite,Thrips palmi, tomato not apply more than 48 fl oz per acre per season.
pinworms,tomato russet mite
*Ambush 25W (permethrin) 3.2-12.8 oz 12 up to day beet armyworm, cabbage looper, Colorado po- 3 Do not use on cherry tomatoes. Do not apply more
of harvest tato beetle, granulate cutworms, hornworms, than 1.2 Ib ai/acre per season (76.8 oz). Not recom-
southern armyworm, tomato fruitworm, mended for control of vegetable leafminer in Florida.
tomato pinworm,vegetable leafminer
*AsanaXL (0.66EC) 2.9-9.6 fl oz 12 1 beet armyworm (aids in control),cabbage 3 Not recommended for control of vegetable leafminer
(esfenvalerate) looper, Colorado potato beetle, cutworms,flea in Florida. Do not apply more than 0.5 Ib ai per acre
beetles, grasshoppers, hornworms,potato aphid, per season, or 10 applications at highest rate.
southern armyworm, tomato fruitworm, tomato
pinworm,whiteflies,yellowstriped armyworm
Assail 70WP (acetamiprid) 0.6-1.7 oz 12 7 aphids, Colorado potato beetle, thrips, 4A Do not apply to crop that has been already treated
whiteflies with imidacloprid or thiamethoxam at planting.
Begin applications for whiteflies when first adults are
noticed. Do not apply more than 4 times per season or
S_ apply more often than every 7 days.
Avaunt(indoxacarb) 2.5-3.5 oz 12 3 beet armyworm, hornworms, loopers, south- 22 Do not apply more than 14 ounces of product per acre
ern armyworm, tomato fruitworm, tomato per crop. Minimum spray interval is 5 days.
pinworm,suppression of leafminers
Aza-Direct azadirachtinn) 1-2 pts, up to 3.5 pts, 4 0 aphids,beetes,caterpillars,leafhoppers,leafmin- 18B Antifeedant, repellant, insect growth regulator.
if needed ers,mites, stink bugs, thrips,weevils, whiteflies OMRI-listed2.
Azatin XL azadirachtinn) 5-21 fl oz 4 0 aphids, beetles, caterpillars, leafhoppers, 18B Antifeedant, repellant, insect growth regulator.
leafminers, thrips, weevils, whiteflies
*Baythroid XL (beta-cyfluthrin) 1.6-2.8 fl oz 12 0 beet armyworm"1,cabbage looper,Colorado 3 "'Ist and 2nd instars only (2Suppression Do not apply
potato beetle,dipterous leafminers(2, European more than 0.132 Ib (Baythroid XL) ai per acre per
corn borer,flea beetles,hornworms,potato season.
aphid,southem armyworm' ,stinkbugs, tomato
fruitworm,tomato pinworm,variegated cut-
worm,westem flower thrips,whitefly adults121
Beleaf 50 SG (flonicamid) 2.0-2.8 oz 12 0 aphids, plant bugs 9C Do not apply more than 8.4 oz/acre per season. Begin
applications before pests reach damaging levels.
Biobit HP (Bacillus thuringiensis 0.5-2.0 Ib 4 0 caterpillars (will not control large armyworms) 11B2 Treat when larvae are young. Good coverage is essen-
subspecies kurstaki) tial. Can be used in the greenhouse. OMRI-listed2.
BotaniGard 22 WP, ES WP: 0.5-2 lb/100 gal 4 0 aphids,thrips,whiteflies May be used in greenhouses. Contact dealer for
(Beauveria bassiana) ES: 0.5-2 qts 100/gal recommendations if an adjuvant must be used. Not
compatible in tank mix with fungicides.



Trade Name Rate REI Days to Insects MOA Notes
(CommonName) (product/acre) (hours) Harvest Code1

*Brigade 2EC (bifenthrin) 2.1-5.2 fl oz 12 1 aphids,armyworms,corn earworm, cutworms, 3 Make no more than 4 applications per season. Do not
flea beetles, grasshoppers, mites, stink bug make applications less than 10 days apart.
spp., tarnished plant bug, thrips, whiteflies
CheckMateTPW, TPW: 200 dispenser 0 0 tomato pinworm For mating disruption
TPW-F (pheromone) TPW-F: 1.2-6.0 fl oz See label.
Confirm 2F (tebufenozide) 6-16fl oz 4 7 armyworms, black cutworm, hornworms, 18A Product is a slow acting IGR that will not kill larvae
loopers immediately. Do not apply more than 1.0 Ib ai per acre
per season.
Coragen (rynaxypyr) 3.5-7.5 fl oz 4 1 beet armyworm, Colorado potato beetle,fall 28 Can be applied by drip chemigation-See label. Do
armyworm, hornworms, leafminer larvae loop- not use more than 15.4fl oz product/acre per crop.
ers, southern armyworm, tomato fruitworm,
tomato pinworm
Courier 40SC (buprofezin) 9-13.6fl oz 12 1 whitefly nymphs 16 See label for plantback restrictions. Apply when a
threshold is reached of 5 nymphs per 10 leaflets from
the middle of the plant. Product is a slow acting IGR
that will not kill nymphs immediately. No more than
2 applications per season. Allow at least 28 days
between applications.
CrymaxWDG 0.5-2.0 Ib 4 0 armyworms, loopers, tomato fruitworm, 11B2 Use high rate for armyworms. Treat when larvae are
(Bacillus thuringiensis tomato hornworm, tomato pinworm young.
subspecies kurstaki)
*Danitol 2.4 EC (fenpropathrin) 10.67 fl oz 24 3 days, beet armyworm, cabbage looper,fruitworms, 3 Use alone for control of fruitworms, stink bugs, tobacco
or 7 if potato aphid, silverleaf whitefly, stink bugs, hornworm, twospotted spider mites, and yellowstriped
mixed thrips, tobacco hornworm,tomato pinworm, armyworms. Tank mix with Monitor 4for all others,
with twospotted spider mites,yellowstriped especially whitefly. Do not apply more than 0.8 Ib ai per
Monitor 4 armyworm acre per season. Do not tank mix with copper.
Deliver (Bacillus thuringiensis 0.25-1.5 Ib 4 0 armyworms, cutworms, loopers, 11B2 Use higher rates for armyworms. OMRI-listed2.
subspecies kurstaki) tomato fruitworm, tomato pinworm
*Diazinon AG500; 4E; AG500,4E: 14 qts 48 preplant cutworms, mole crickets, wireworms 1B Incorporate into soil see label.
*50W(diazinon) 50W: 2-8 Ib
Dimethoate 4 EC, 4EC: 0.5-1.0 pt 48 7 aphids, leafhoppers, leafminers 1B Will not control organophosphate-resistant leafmin-
2.67 EC (dimethoate) 2.67:0.75-1.5 pt ers.
DiPel DF (Bacillus thuringiensis 0.5-2.0 Ib 4 0 caterpillars 11B2 Treat when larvae are young. Good coverage is es-
supspecies kurstaki) sential. OMRI-listed2.
Entrust (spinosad) 0.5-2.5 oz 4 1 armyworms, Colorado potato beetle,flower 5 Do not apply more than 9 oz per acre per crop.
thrips, hornworms, Liriomyza leafminers, OMRI-listed2.
loopers, other caterpillars, tomato fruitworm,
tomato pinworm
Esteem Ant Bait (pyriproxyfen) 1.5-2.0 Ib 12 1 red imported fire ant 7C Apply when ants are actively foraging.
Extinguish ((S) methoprene) 1.0-1.5 Ib 4 0 fire ants 7A Slow acting IGR (insect growth regulator). Best ap-
plied early spring and fall where crop will be grown.
Colonies will be reduced after three weeks and elimi-
nated after 8 to 10 weeks. May be applied by ground
equipment or aerially.
Fulfill (pymetrozine) 2.75 oz 12 0 if 2 green peach aphid, potato aphid, suppression 9B Do not make more than four applications. (FL-040006)
applica- ofwhiteflies 24(c) label for growing transplants also (FL-03004).
3 or
4 applica-
Intrepid 2F (methoxyfenozide) 4-16 fl oz 4 1 beet armyworm,cabbage looper,fall armyworm, 18A Do not apply more than 64fl oz acre per season.
hornworms, southern armyworm,tomatofruit- Product is a slow-acting IGR that will not kill larvae
Sworm,true armyworm,yellowstriped armyworm immediately.
Javelin WG (Bacillus thuringiensis 0.12-1.5 Ib 4 0 most caterpillars, but not Spodoptera species 11B2 Treat when larvae are young. Thorough coverage is
subspecies kurstaki) armywormss) essential. OMRI-listed2.
Knack IGR (pyriproxyfen) 8-10 fl oz 12 14 immature whiteflies 7C Apply when a threshold is reached of 5 nymphs per 10
7 SLN leaflets from the middle of the plant Product is a slow
No FL- acting IGR that will not kill nymphs immediately. Make no
200002 more than two applications per season.Treat wholefields.
Kryocide (cryolite) 8-16 Ib 12 14 armyworm,blister beetle, cabbage looper,Colo- 9A Minimum of 7 days between applications. Do not ap-
rado potato beetle larvae,flea beetles,horn- ply more than 64 Ibs per acre per season.
worms,tomato fruitworm, tomato pinworm
*LannateLV,*SP (methomyl) LV: 1.5-3.0pt 48 1: aphids,armyworm,beetarmyworm,fall 1A Do not apply more than 21 ptLV/acre/crop(15for
SP: 0.5-1.0 Ib armyworm, hornworms, loopers, southern ar- tomatillos) or 7 Ib SP/acre/crop (5 Ib for tomatillos).
myworm, tomato fruitworm, tomato pinworm,
variegated cutworm
LepinoxWDG (Bacillus thuringi- 1.0-2.0 Ib 12 0 for most caterpillars, including beet army- 11B2 Treat when larvae are small. Thorough coverage is
ensis subspecies kurstaki) worm (see label) essential.
Malathion 5 1.0-2.5 .0 pt 12 1 aphids,Drosophila,mites 1B Can be used in greenhouse (8F).
Malathion 8 F 1.5-2 pt
*Monitor 4EC (methamidophos) 1.5-2 pts 96 7 aphids,fruitworms, leafminers, tomato pin- 1 B 'Suppression only (2Use as tank mix with a pyre-
[24(c) labels] worm'11, whiteflies121 throid for whitefly control. Do not apply more than
FL-800046 8 pts per acre per crop season, nor within 7 days of
FL-900003 harvest.
M Pede49% EC 1-2% V/V 12 0 aphids, leafhoppers, mites, plantbugs, thrips, -- OMRI-listed2.
(Soap, insecticidal) whiteflies
*Mustang Max *Mustang Max EC 2.24-4.0 oz 12 1 beet armyworm,cabbage looper,Colorado 3 Not recommended for vegetable leafminer in Florida.
(zeta cypermethrin) potato beetle,cutworms,fall armyworm,flea Do not make applications less than 7 days apart. Do
beetles,grasshoppers,green and brown stink not apply more than 0.15 Ib ai per acre per season.
bugs, hornworms, leafminers, leafhoppers, Lygus
bugs, plant bugs, southern armyworm, tobacco
budworm,tomatofruitworm,tomato pinworm,
true armyworm,yellowstriped armyworm. Aids
_______ in control of aphids,thrips and whiteflies.


Trade Name Rate REI Days to Insects MOA Notes
(Common Name) (product/acre) (hours) Harvest Code1

Neemix 4.5 azadirachtinn) 4-16floz 12 0 aphids,armyworms,hornworms, 18B IGR,feeding repellant. OMRI-listed2.
psyllids, Colorado potato beetle, cutworms,
leafminers, loopers, tomato fruitworm (corn
earworm), tomato pinworm,whiteflies
NoMate MEC TPW (pheromone) 0 0 tomato pinworm See label.
Oberon 2SC(spiromesifen) 7.0-8.5 fl oz 12 7 broad mite,twospotted spider mite,whiteflies 23 Maximum amount per crop: 25.5 fl oz/acre. No more
(eggs and nymphs) than 3 applications.
Platinum 5-11 fl oz 12 30 aphids,Colorado potato beetles,flea beetles, 4A Soil application. See label for rotational restrictions.
Platnum 75 SG (thiamethoxam) 1.66-3.67 oz leafhoppers,thrips, tomato pinworm, whiteflies Do not use with other growth insecticides
*Pounce 25 W (permethrin) 3.2-12.8 oz 12 0 beet armyworm, cabbage looper, Colorado 3 Do not apply to cherry or grape tomatoes (fruit less
potato beetle, dipterous leafminers, granulate than 1 inch in diameter). Do not apply more than 1.2
cutworm, hornworms, southern armyworm, Ib ai per acre per season.
tomato fruitworm, tomato pinworm
*Proaxis Insecticide 1.92-3.84fl oz 24 5 aphids(', beet armyworm2, blister beetles, 3 "'Suppression only. 2)First and second instars only. Do
(gamma-cyhalothrin) cabbage looper, Colorado potato beetle, not apply more than 2.88 pints per acre per season.
cucumber beetles (adults), cutworms,
hornworms,fall armyworm(2),flea beetles,
grasshoppers, leafhoppers, plant bugs, south-
ern armyworm2), spider mites(, stink bugs,
thrips'(, tobacco budworm, tomato fruitworm,
tomato pinworm,vegetable weevil (adult),
whiteflies", yellowstriped armyworm(2)
*Proclaim (emamectin benzoate) 2.4-4.8 oz 12 7 beet armyworm, cabbage looper,fall army- 6 No more than 28.8 oz/acre per season.
worm, hornworms, southern armyworm,
tobacco budworm, tomato fruitworm, tomato
pinworm,yellowstriped armyworm
Prokil Cryolite 96 (cryolite) 10-16 b 12 14 blister beetle, cabbage looper, Colorado 9A Minimum of 7 days between applications. Do not
potato beetle larvae,flea beetles, hornworms apply more than 64 Ibs per acre per season. Not for
cherry tomatoes.
Provado 1.6F (imidacloprid) 3.8-6.2 fl oz 12 0 aphids, Colorado potato beetle, leafhoppers, 4A Do not apply to crop that has been already treated
whiteflies with imidacloprid or thiamethoxam at planting. Maxi-
mum per crop per season 19 fl oz per acre.
Pyrellin EC (pyrethrin + 1-2 pt 12 12 hours aphids,Colorado potato beetle,cucumber 3,21
rotenone) beetles, flea beetles,flea hoppers, leafhoppers,
leafminers, loopers, mites, plant bugs, stink
bugs, thrips, vegetable weevil, whiteflies
Radiant SC (spinetoram) 5-10 fl oz. 4 1 armyworms, Colorado potato beetle,flower 5 Maximum of 34fl oz per acre per season.
thrips, hornworms,Liriomyza leafminers,
loopers,Thrips palmi, tomato fruitworm,
tomato pinworm
Sevin 80S; XLR; 4F (carbaryl) 80S: 0.63-2.5 12 3 Colorado potato beetle, cutworms,fall army- 1A 'suppression Do not apply more than seven times.
XLR; 4F: 0.5-2.0 worm,flea beetles,lace bugs,leafhoppers,plant Do not apply a total of more than 10 Ib or 8 qt per
A bugs, stink bugs"', thrips'',tomato fruitworm, acre per crop.
tomato hornworm, tomato pinworm,sowbugs
10% Sevin Granules (carbaryl) 20 Ib 12 3 ants,centipedes,crickets,cutworms,earwigs, 1A Maximum of 4 applications, not more often than once
grasshoppers, millipedes, sowbugs, springrails every 7 days.
SpinTor 2SC (spinosad) 1.5-8.0 fl oz 4 1 armyworms, Colorado potato beetle,flower 5 Do not apply to seedlings grown for transplant within
thrips, hornworms, Liriomyza leafminers, a greenhouse or shadehouse. Leafminer and thrips
loopers,Thrips palmi, tomato fruitworm, control may be improved by adding an adjuvant. Do
tomato pinworm not apply more than three times in any 21 day period.
Do not apply more than 29 oz per acre per crop.
Sulfur (many brands) See label 24 see label tomato russet mite,twospotted spider mite May burn fruit and foliage when temperature is high.
Do not apply within 2 weeks of an oil spray or EC
*TeloneC 35 (dichloropropene+ See label 5 preplant garden centipedes (symphylans),wireworms See supplemental label for restrictions in certain
chloropicrin) days Florida counties.
*Telone II (dichloropropene) (See
*Thionex EC 0.66-1.33 qt 24 2 aphids,blister beetle,cabbage looper, Colo- 2 Do not exceed a maximum of 3.0 Ib active ingredient
*Thionex 50W endosulfann) 1.0-2.9 Ib rado potato beetle, flea beetles, hornworms, per acre per year or apply more than 6 times. Can be
stink bugs, tomato fruitworm, tomato russet used in greenhouse.
mite, whiteflies, yellowstriped armyworm
Trigard (cyromazine) 2.66 oz 12 0 Colorado potato beetle (suppression of), 17 No more than 6 applications per crop. Does not
leafminers control CPB adults. Most effective against 1st & 2nd
instar larvae.
Trilogy (extract of neem oil) 0.5-2.0% V/V 4 0 aphids, mites, suppression of thrips and 18B Apply morning or evening to reduce potential for leaf
whiteflies burn. Toxic to bees exposed to direct treatment. Do
not exceed 2 gal/acre per application. OMRI-listed2.
Ultra Fine Oil, 3-6 qts/100 gal water 4 0 aphids, beetle larvae, leafhoppers, leafminers, Do not exceed four applications per season.
JMS Stylet-Oil, and others (JMS) mites, thrips, whiteflies, aphid-transmitted
(oil, insecticidal) 1-2 gal/100 gal viruses (JMS) Organic Stylet-Oil and Saf-T-Side are OMRI-listed2.
Venom Insecticide (dinotefuran) foliar: 1-4 oz 12 foliar: 1 Colorado potato beetle,flea beetles, leafhop- 4A Use only one application method (soil or foliar). Lim-
soil: 5-6 oz soil: 21 pers, leafminers, thrips, whiteflies ited to three applications per season. Do not use on
grape or cherry tomatoes. Toxic to honeybees.
*Vydate L (oxamyl) foliar: 2-4 pt 48 3 aphids,Colorado potato beetle,leafminers 1A Do not apply more than 32 pts per acre per season.
(except Liriomyza trifolii), whiteflies (suppres-
sion only)
*Warrior II (lambda cyhalothrin) 0.96-1.92 fl oz 24 5 aphids"', beet armyworm(2, cabbage 3 "'suppression only (2for control of 1st and 2nd instars
looper, Colorado potato beetle, cutworms, only. Do not apply more than 0.36 Ib ai per acre per
fall armyworm2), flea beetles, grasshoppers, season. (3)Does not control western flower thrips.
hornworms, leafhoppers, leafminers"', plant
bugs, southern armyworm2', stink bugs,
thrips()', tomato fruitworm, tomato pinworm,
whiteflies"',yellowstriped armyworm(2)



Trade Name Rate REI Days to Insects MOA Notes
(Common Name) (product/acre) (hours) Harvest Code'
Xentari DF (Bacillus thuringiensis 0.5-2 Ib 4 0 caterpillars 11B1 Treat when larvae are young. Thorough coverage is
subspecies aizawai) essential. May be used in the greenhouse. Can be used
in organic production. OMRI-listed2.

'Mode of Action codes for vegetable pest insecticides from the Insecticide Resistance Action Committee (IRAC) Mode of Action Classification v.6.1 August 2008.
1A. Acetylcholinesterase inhibitors, Carbamates (nerve action)
1 B. Acetylcholinesterase inhibitors, Organophosphates (nerve action)
2A. GABA-gated chloride channel antagonists (nerve action)
3. Sodium channel modulators (nerve action)
4A. Nicotinic acetylcholine receptor agonists (nerve action)
5. Nicotinic acetylcholine receptor allosteric activators (nerve action)
6. Chloride channel activators (nerve and muscle action)
7A. Juvenile hormone mimics (growth regulation)
7C. Juvenile hormone mimics (growth regulation)
9B and 9C. Selective homopteran feeding blockers
10. Mite growth inhibitors (growth regulation)
11.Microbial disruptors of insect midgut membranes
12B. Inhibitors of mitochondrial ATP synthase (energy metabolism)
15. Inhibitors of chitin biosynthesis, type 0,lepidopteran (growth regulation)
16. Inhibitors of chitin biosynthesis, type 1,homopteran (growth regulation)
17. Molting disruptor, dipteran (growth regulation)
18. Ecdysone receptor agonists (growth regulation)
22.Voltage-dependent sodium channel blockers (nerve action)
23. Inhibitors of acetyl Co-A carboxylase (lipid synthesis, growth regulation)
28. Ryanodine receptor modulators (nerve and muscle action) un. Compounds of unknown or uncertain mode of action
2 OMRI listed: Listed by the Organic Materials Review Institute for use in organic production.
* Restricted Use Only



Joseph W. Noling, Extension Nematology, University of Florida/IFAS, Citrus
Research & Education Center, Lake Alfred, jnoling@ufl.edu

Joseph W. Noling, Extension Nematology, UF/IFAS, Citrus Research & Education Center, Lake Alfred, FL, jnoling@ufl.edu
Methyl Bromide'' 50-50 300-480 Ib 12" 3 150-240 Ib 6.8-11.0 Ib
Chloropicrin EC' 300-500 Ib Drip applied See label for use guidelines and additional considerations
Chloropicrin' 300-5001b 12" 3 150-250 Ib 6.9-11.5 Ib
PIC Chlor 60' 19.5-31.5 gal 12" 3 20-25 gal/250-300 Ib 57-90 fl oz
Telone 112 9-18 gal 12" 3 4.5-9.0 gal 26-53 fl oz
Telone EC2 9-18 gal Drip applied See label for use guidelines and additional considerations
Telone C-172 10.8-17.1 gal 12" 3 5.4-8.5 gal 31.8-50.2 fl oz
Telone C-352 13-20.5 al 12" 3 6.5-13 gal 22-45.4fl oz
Telone Inline2 13-20.5 gal Drip applied See label for use guidelines and additional considerations
Metham Sodium 50-75 gal 5" 6 25-37.5 gal 56-111 fl oz

VydateL treat soil before or at planting with any other appropriate nematicide or a Vydate transplant water drench followed byVydate foliar sprays at 7 14 day intervals through the season; do
not apply within 7 days of harvest; refer to directions in appropriate"state labels'which must be in the hand of the user when applying pesticides under state registrations.

1 If treated area is tarped with impermeable film, dosage may be reduced by 40-50%.
2The manufacturer of Telone II,Telone EC,Telone C 17,Telone C-35, and Telone Inline has restricted use only on soils that have a relatively shallow hard pan or soil layer restrictive to downward
water movement (such as a spodic horizon) within six feet of the ground surface and are capable of supporting seepage irrigation regardless of irrigation method employed. Crop use of Telone
products do not apply to the Homestead, Dade county production regions of south Florida. Higher label application rates are possible for fields with cyst-forming nematodes. Consult manufac-
turers label for personal protective equipment and other use restrictions which might apply.
As a grandfather clause, it is still possible to continue to use methyl bromide on any previous labeled crop as long as the methyl bromide used comes from existing supplies produced prior
to January 1,2005. A critical use exemption (CUE) for continuing use of methyl bromide for tomato, pepper, eggplant and strawberry has been awarded for calendar years 2005 through 2009.
Specific, certified uses and labeling requirements for CUE acquired methyl bromide must be satisfied prior to grower purchase and use in these crops. Product formulations are subject to change
and availability.
Rate/acre estimated for row treatments to help determine the approximate amounts of chemical needed per acre of field. If rows are closer, more chemical will be needed per acre; if wider, less.
Reduced rates are possible with use of gas impermeable mulches.

Rates are believed to be correct for products listed when applied to mineral soils. Higher rates may be required for muck (organic) soils. Growers have the final responsibility to guarantee
that each product is used in a manner consistent with the label. The information was compiled by the author as of July 1,2009 as a reference for the commercial Florida tomato grower. The
mentioning of a chemical or proprietary product in this publication does not constitute a written recommendation or an endorsement for its use by the University of Florida, Institute of Food
and Agricultural Sciences, and does not imply its approval to the exclusion of other products that may be suitable. Products mentioned in this publication are subject to changing Environmental
Protection Agency (EPA) rules, regulations, and restrictions. Additional products may become available or approved for use.


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