Title: Berry/vegetable times
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00087388/00066
 Material Information
Title: Berry/vegetable times
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
Place of Publication: Gainesville, Fla.
Publication Date: June 2010
 Record Information
Bibliographic ID: UF00087388
Volume ID: VID00066
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.


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5Berry/Vegetable Times

June 2010

Calendar of Events

July 31 & Aug. 1 Florida Small
Farms and Alternative Enterprises,
Osceola Heritage Park Conference
Center, Kissimmee. For more
information visit: http://

Aug. 17 & 18 FSGA Agritech
Educational Sessions and Trade
Show. Trinkle Building, Plant
City. For more information contact
the FSGA. www.flastrawberry.com.

Sept. 7 Tomato Institute, Ritz
Carlton, Naples. For more
information go to http://

Nov. 10 2010 AgExpo at GCREC.
For more information go to http://

Feb. 11, 2011. Strawberry Field
Day at GCREC. More details to

Feb. 8-11, 2011 North American
Strawberry Growers Association
and North American Strawberry
Research Symposium Joint
Meeting. Tampa. For more
information go to www.nasga.org.

A University of Florida/IFAS and Florida
Cooperative Extension Service
Hillsborough County, 5339 CR 579
Seffner, FL 33584 (813) 744-5519
Alicia Whidden, Editor
Gulf Coast Research & Education Center
14625 County Road 672,
Wimauma, FL 33598 (813) 634-0000
Jack Rechcigl, Center Director
Christine Cooley, Layout and Design
James F. Price, Co-Editor

Fromw Your A gent
Spotted Wing Drosophila Fly Now Found in

The spotted wing drosophila fly (SWD), Drosophila
suzukii, has now been found in blueberries in Hillsborough
County. Back at the 2009 Agritech, Dr. Jim Price had
warned strawberry growers to be on the lookout for the
coming season and several days later it was found to be here.
Dr. David Dean, of the Fruit Fly Laboratory in Palmetto,
found SWD in early August 2009 in Hillsborough County
and now it has spread to 23 counties in the southern part of
the state in under 45 weeks (see additional article by Jim Price
and Curtis Nagle in this issue, Page 5).

(Continued on page 2)

Nematode Management and Soil Fumigant
J.W. Noling' Andrew MacRae2 and Alicia Whidden3
1CREC, 2GCREC, 3 Hillsborough County Cooperative Extension Service

What a season! Easter has come and gone and the
double cropping season is about over. In driving around the
area, it is clear that there is a lot of double cropped strawberry
planned for the fall. There are even some fields in which a
third crop of strawberry on the same plastic is planned for the
fall. In general, most growers who double cropped strawberry
last year seemed to have done quite well. In some fields
where nematodes became a problem in the 2nd crop, weed
growth in the middles and many of plant holes seems to have
been the causal issue for increasing nematode populations. In
other cases, the drip tape and the nonuniform delivery of a
drip applied fumigant was the culprit. We can not over
emphasize the season long need for weed control and the need
for a clean, functional drip tape as nematode management
(Continued on page 2)


IFAS is an Equal Employment OpportunityAffirmative Action Employer authorized to provide research, educational
formation and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin U S Department ofAgriculture, Coopera-
tive Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of the County Commissioners Cooperating

(Continued from page 1)
SWD is one of two drosophila that
can damage intact fruit. Dr. Price in an
earlier Berry/Vegetable Times article told us
how fruit are attacked. Usually fruit flies
affect only fruit that are overripe or have
some type of skin damage. SWD can
damage thin skinned fruit that has no
opening. This is done by the female fly, that
has a serrated ovipositor and can cut a hole in
the fruit then deposit an egg. When the egg
hatches the larva eat the fruit pulp and can
cause a sunken area to form. Besides the
larvae being in the fruit, decay organisms can
enter the hole that was cut and cause fruit rot.
Dr. Dean has reported finding SWD
in strawberries, blueberries, Surinam cherry,
orange Jessamine fruit, red mulberry and
believes it can also go to elderberry. In the
northwest part of the country last year,
cherries and blueberries were severely
affected. We have been lucky this
strawberry and blueberry season not to have
had much fruit damage from SWD. Even
though we had a record breaking cold winter
it did not get rid of SWD. This fly is
originally from Japan and is very cold hardy.
In the future this is a pest we will need to
watch out for.
Two IFAS researchers that will be
watching out for SWD in the future will be
Dr. Jim Price for strawberries and Dr. Oscar
Liburd for blueberries. As Dr. Price said in a
talk he gave on SWD, "The bottom line on
spotted wing drosophila is that it will become
permanent and can't be ignored. We will be
able to manage it and it will not be

Have a good summer,

813-744-5519 ext. 134
awhidden@ulf edu

(Continued from page 1)
considerations in these double cropped fields.
Run and clean the irrigation periodically and
don't let the fennel, grasses, nightshades, and
pigweeds get six feet out of control.
We know there are a lot of growers who
are in the final stages of constructing the
production plan for next year and because of
this, there are a number of things we would like
to share with you which might be of help in
making those decisions. The first thing we would
like to share with you is to describe an encounter
we had with EPA officials who were conducting
a training exercise for state inspectors
summarizing the new fumigant label
requirements forthcoming this fall, including
buffer zones, fumigant management plans, and
air monitoring programs among a myriad of
other label changes. Inclusive to classroom type
training exercises was a GCREC field tour and
demonstration this past April that Andrew
MacRae largely put together. He did a fine job.
For the drip fumigation demonstration, it is
appropriate that we thank Hendrix and Dail
(Jimmy Moden) and Dow Agrosciences (Jerry
Nance) who were kind enough to construct a
'state-of-the-art' drip fumigation station which
allowed us to describe the drip fumigation
process and essential backflow and delivery
components of the injection system. During the
field presentation, I described how drip
fumigation had expanded in acreage, particularly
as a necessary nematode management
component for double cropping and sting
nematode control. Some time later, after lunch, I
was pulled aside and asked by EPA whether drip
fumigation under 'holey' plastic was not a label
violation when the fumigant label states a
'mandatory tarp seal is required' for application
of this fumigant product. My response was to ask
them whether a plastic tarp was present and
whether it was not performing at least a marginal
seal of the plant bed. They were quick to indicate
that this was not their intent, nor did they believe
that a truly functional seal exists with as many as
20,000 /acre open planting holes in the plastic

mulch from the previous year's strawberry
plants. Needless to say, as the various
fumigant labels are being rewritten by the
chemical manufacturers and which must then
be approved by EPA before they appear on
cylinders as early as December 1, 2010, I
think it is safe to say the days of drip
fumigating holey plastic are over (after
December) unless a new system of covering
the bed top with new plastic is developed for
some fumigants (i.e., Telone). We are
hoping we might be in a position to evaluate
a new mulch laying and gluing system this
fall prior to drip fumigation in double
cropped fields. Stay tuned, because if you
have interest, we may need some candidate
fields in which to test the new system.

Methyl Bromide Alternatives
This past season, a number of methyl
bromide alternative fumigants and gas
impermeable mulch films were evaluated in
grower demonstration trials. Hopefully you
were able to view and compare treatments in
some of the trials we put out this past fall.
The fumigant treatments evaluated generally
included Telone C35 (35-42 gpa); Midas
50/50 (125 lb/a); Pic Clor 60 (300 lb/a);
Dimethyl Disulfide with Chloropicrin
(Paladin) (60 gpa); and Telone InLine (35
gpa). All rates being expressed as per treated
acre while use rates per acre are computed as
62.5% of treated acre rates. None of the
fumigants listed above faired poorly in any
of trials. The extraordinarily cold winter in
central Florida this past year resulted in a
significant reduction of approximately 45%
from average strawberry crop yields from the
previous year. For the majority of an 8 week
period (January + February), soil
temperatures at 5 inches persisted at levels
below 60 F. The combination of
unseasonably cool air and soil temperatures
slowed growth significantly. The protracted
cold weather and needs for repeated
overhead irrigation for cold protection,

resulted in reduced plant growth and fruit
production, and of fruit produced, resulted in
significant amount of cull fruit during January.
Fruit production did not begin in earnest until
early February, at which time a glut of fruit was
observed in the market. This was a tough year
for strawberry field research in Florida. In
general, we did not see meaningful differences
between shank applied fumigant treatments
under new plastic this past year.
This past year we also continued our
research focus on drip formulations of some of
the alternative fumigants. We focused on the
drip fumigants metam sodium (Vapam), Telone
EC, and Telone Inline applied as one of nine
different combinations of crop termination
treatments in the spring after the initial crop of
strawberry, followed by a stale bed fallow
treatment during the summer, and concluding in
fall with another preplant drip fumigant
treatments. These studies were initiated, out of
necessity, because of 2008-09 strawberry
market conditions and needs of strawberry
growers to reduce production costs. Thinking
about production levels achieved this year and
the degree to which growers are again planning
double cropping bring on the experience of deja
vu. Due to low yields obtained following the
atypical and unseasonably cold temperatures
which persisted during January 2010 and
beyond, we were not able to characterize fully
the impacts (positive or negative) of double
cropping. The data do indicated that overall
yields within the double crop treatments were
significantly lower than yield obtained with
shank or drip applied fumigants under new
plastic (Graph 1). We were able to show a soil
heating effect, a type of solarization treatment
during the summer off-season. Temperature
probes installed into stale-beds on east and west
bed shoulders and bed center locations
demonstrated that soil temperature at 12 inch
depth could attain temperatures of 100 to 110F
on a daily basis. These results suggested that
crop termination treatments with either metam
sodium, Telone EC, or Telone Inline did not

necessarily have to be 100% effective to
provide nematode control within strawberry
plant beds. The results from other trials again
demonstrated strawberry yield enhancement
with the addition of a second drip per bed,
particularly as a way in which to enhance the
fumigation effect of the drip fumigant.
Additional research is required to validate
the fumigant, horticultural, and economic
benefits of the drip fumigants and additional
drip tape. Regardless of fumigant or number
of drip tapes per bed, to maximize lateral
spread, growers should plan on a fumigant
injection period to deliver 125 to 150 gal/
100 linear feet of row. This equates to at
least 13,500 gallons or about 50% (0.50) of a
broadcast acre inch of water (1 acre inch is
27,154 gallons water).

Remote Sensing
For the past five years we have toyed around
with different camera platforms in which to
take pictures of strawberry plants. Some of
you have observed us with the long
telescopic rods or 6 ft helium balloons, the
cameras mounted to wing spars on airplanes
or mounted on an old motorized bicycle cart,
or even strapped to a cage on a big 30 ft
forklift to take aerial pictures. This year we
decided to intensify our efforts and acquired
an old FarmAll 140 which we set up with 9
inch tires on 4 ft centers and then constructed
the platforms for GPS, cameras and
computer (Figure 1). The tractor mounted
camera is being used to scan strawberry rows
to provide estimates of green canopy cover
against a backdrop of black plastic mulch
covering the raised bed. We are fortunate that
in the last few years we have been able to
quantify strawberry yield losses with the
plant stunting effect caused by sting
nematode. Preliminary finding look pretty
good. Strawberry yields from commercially
hand harvested large plots have been well
described by yield index values we derive
from assessment of plants of different sizes

within the same plots. Using plant stunting and
counts of different plant sizes, we have
conducted chemical treatment evaluations in
over 50 commercial fields with recurring
histories of sting nematode problems. In these
fields, we have been able to develop accurate
maps of nematode distribution, crop yields and
loss indices associated with the different
fumigant treatments. We will be continuing the
field scale evaluations this fall because we
really believe the methodology is capable of
providing growers considerable guidance and
quantitative performance data in which to
recommend the various alternatives to methyl
bromide soil fumigation for nematode
management. Much of the final end-of-season
remote sensing surveys we conducted this past
spring are still being analyzed, so any further
discussion of the results will have to wait for a
subsequent newsletter or AgriTech seminar.

Traffic Pan Research:
Much of the performance inconsistencies of
methyl bromide alternatives is currently
thought to be attributed to and limited by the
presence of plow pans or traffic pans (8-18")
underlying many, if not all, Florida strawberry
fields. In general, this dense compacted layer
begins just below the deepest tillage
implements used in the field. Previous research
has demonstrated that some fumigant gases do
not diffuse through the impermeable layer to
depths where sting nematodes reside. If the
traffic pan is not destroyed, then at least part of
the overall soil population of sting nematode
survive to migrate upwardly into the bed and
cause irresolvable damage to the strawberry
crop. This is what we think and we're sticking
by it. In March we acquired, with the greatly
appreciated help and assistance of Hendrix and
Dail (Jimmy Moden), a 36 inch subsoiler from
Georgia. Fortunate for us the subsoiler was
also plumbed to deliver soil fumigants into
deep soil (Figure 2). With the subsoiler, our
objective is to destroy the compacted layer and
introduce the fumigant below the traffic pan at

the same time. In the trials we have
completed so far, Telone II (12gpa) has been
applied during either the first or second
ripping pass to a depth of 20 inches with the
ripper shanks spaced on about 12 inch
centers. After injection, the field is then
cultivated and rolled, and overhead
sprinklers run to provide a surface water seal.
By coupling deep injection of Telone (1,3-D)
with the subsoiling to destroy the compact,
gas impermeable traffic pan, we believe we
will address and remediate the single most
important soil factor causing significant
performance inconsistency with the
alternative fumigants in sting nematode
infested fields. I think we should also
mention that we are still looking for
nematode fields with interested cooperators
to test the hypothesis and the application

Figure 1. New tractor (1964) and remote sensing
equipment being used to characterize and map sting
nematode distribution and damage by row within
strawberry fields.

P <0f01

Cropping System

Graph 1. Relative strawberry yields computed from
an average plant size assessment of plants grown on
new plastic following soil fumigant treatment (single
crop) compared with strawberry grown as a second
crop after strawberry (double crop) following
application of a drip fumigant under holey plastic.
FSGA 2010.

Figure 2. Subsoiler being used to destroy highly
compacted, subsurface traffic pan and to deliver
fumigants 20-24 inches deep into soil. Authors would
like to acknowledge gratefully that the subsoiler was
provided courtesy of Jimmy Moden, Hendrix & Dail,
Palmetto, FL.

Current Status of Spotted Wing
Drosophila in Florida
J. F. Price and C. A. Nagle, GCREC

Dr. David Dean, entomologist in the
Florida Department of Agriculture and
Consumer Services, Division of Plant Industry
(FDACS DPI) fruit fly laboratory in Palmetto,
maintains records of spotted wing drosophila

(Continued on page 6)

occurrence throughout Florida. This work is adjunct to DPI responsibility for monitoring and
mitigating the larger, long experienced, tephritid fruit flies such as Mediterranean fruit fly.
Figure 1 incorporates a map of the southern two-thirds of our peninsula and depicts the
locations of spotted wing drosophila (SWD) encountered so far. Although the map covers only
a portion of Florida, trapping takes place over much of the state and more will be established
into the panhandle soon. No SWD have been discovered elsewhere in Florida. Additionally,
we know of no discoveries of SWD in the eastern US outside of Florida.
Dr. Dean emphasizes caution in interpreting data from his map. There are areas in
Florida where many finds have occurred and others where few have occurred (see the patterns
of yellow dots). Numbers of finds are products of not only the presence of SWD, but also the
intensity of trapping in that area. This means that one should not conclude that there many
SWD around Tampa Bay and few in Highlands County. There are more traps around Tampa
Bay than in Highlands County. The reason for the disparity is that in the tephritid fruit fly
program, specialists intensify their investigations around likely areas of tephritid fruit fly
entry... seaports, major airports, and travelling population centers.
The first SWD flies were trapped in Florida in August 2009 and we became concerned
for our strawberry crop. The long period of extreme cold this winter likely saved considerable
problems in our berry production. The first strawberry field to be known with SWD was
discovered late in the season. There have been a few finds of SWD in blueberries and

(Continued on page 7)

I.spilde Drsphl suzi Find by County

County Count of TotallSum of Total
1 BROWARD 23 120
3 CITRUS 1 1
5 DADE 51 175
6 DESOTO 1 1
7 HARDEE 1 1
8 HENDRY 1 2
13 LAKE 1 1
14 LEE 5 13
15 MANATEE 19 98
16 MARTIN 1 1
17 ORANGE 1 1
18 OSCEOLA 1 1
19 PALM BEACH 17 113
20 PINELLAS 28 44
21 POLK 2 3
22 SARASOTA 22 102
23 ST LUCIE 1 1
Grand Total 370 1460

REV 5/20/2010
REV 5/07/2010 W E
REV 4/30/2010 LEGEND
REV 4/23/2010
REV 4/19/2010 I = County Boundary
REV 4/09/2010 12.5 25 50 Miles
3/18/2010 0 = Drosophila suzukii find I , , ,


(Continued from page 6)
blackberries, but no big losses. This insect is
a cool weather pest and likely will remain at
low levels in our environment until fall.
If Florida experiences a mild winter
next season, then the outcome for berry
growers probably will be different from their
experiences this year. Regardless of the
winter and its impact on SWD, we believe
that tools are available to manage the
problem in strawberries next season without
major losses.

Tomato Bacterial Speck and Spot:
an update on the bacterial speck
outbreak of 2010
Gary Vallad, Pam Roberts, and Jeff Jones
GCREC, SWFREC, and Dept. of Plant Pathology,

With summer at our doorstep, it's
hard to believe we just dealt with one of the
coldest and wettest winters on record. The
unprecedented weather not only reduced
transplant establishment, plant vigor, and
yields, but set the stage for one of the largest
outbreaks of bacterial speck caused by
Pseudomonas syringae pv. tomato seen in
nearly two decades. Tomato production in
Collier and Hendry Counties were most
severely affected with early planted fields
exhibiting severe foliar blighting and large
stem lesions (Figure 1). Fields planted in
February and later appeared to fare better;
that is they were not impacted by the large
stem lesions. Bacterial speck severity on
tomato varied in Hillsborough, Manatee, and
Hardee Counties, with moderate foliar
symptoms in early planted material (January
through early February) and only minor
symptoms in later planted materials. None
of the severe stem lesions were observed in
Hillsborough, Manatee, or Hardee Counties.
Whether P.s. tomato alone accounted for the
unusual stem lesions, either exacerbated by

the unusual weather or associated with another
pathogen remains unclear. Under such
extreme conditions, it is not unusual to find
opportunistic microorganisms (or weak
pathogens) that are not commonly associated
with plant disease, but are exploiting plant
tissues compromised by injury or stress.
Pseudomonas syringae pv. tomato
could be considered the cool weather cousin to
Xanthomonas perforans (formerly called
Xanthomonas axonopodis pv. vesicatoria or
Xanthomonas campestris pv. vesicatoria) the
causal agent of bacterial spot. Bacterial speck
is favored by high relative humidity and
temperatures of 64 to 75 F, however the
bacterium can still persist at temps as high as
85 F (as it currently is in many fields
throughout Hillsborough, Manatee, and Hardee
Counties). Bacterial spot is favored by
temperatures above 75 F in addition to high
relative humidity. Symptoms of both bacterial
speck and spot affect the foliage, stems,
petioles, inflorescent tissues and fruit of
tomato, and can be tricky to differentiate in the
field. Foliar symptoms of both consist of
small circular lesions that can coalesce under
ideal conditions leading to general blighting of
foliage. Bacterial spot lesions are generally
brown with a greasy appearance when the
relative humidity is high (Figures 2 and 3).
Bacterial speck lesions are often dark brown to
black, lack the greasy appearance, and often
surrounded by a discrete chlorotic (yellow)
halo (Figures 2 and 3). However, this
chlorotic halo is not always diagnostic, as it is
typically associated with mature bacterial
speck lesions and may develop slower
depending on environmental conditions and
cultivar susceptibility. Also, leaves severely
affected by bacterial spot often develop a
general chlorosis that usually leads to blighting
and can lead to some confusion. Don't be
fooled by the disease name, as bacterial speck
lesions can be as large or larger than bacterial
spot lesions; however, the margins of speck
lesions are usually more angular than spot

(Continued from page 7)
lesions. Bacterial speck and spot are more
clearly differentiated by fruit symptoms.
Fruit lesions of bacterial speck are slightly
raised (or sunken), generally much smaller
(1/16 in.) than those of bacterial spot, are
quite superficial, and do not crack or become
scaly as those associated with bacterial spot
(Figure 4).
Disease management for bacterial
speck and spot is very similar, and requires
an integrated approach for best results:
1. Rotate tomato fields to avoid
carryover on crop residue. Neither
bacterium survives long in the
absence of host material; however,
P.s. tomato is able to survive in crop
residue for an extended period (up to
30 weeks in some studies).
2. Eliminate any volunteers and weed
species (especially solanaceous
weeds) that can act as a reservoir.
Pseudomonas syringae pv. tomato
can survive on the leaves and roots of
3. Start with clean, healthy transplants
preferably produced in facilities
removed from tomato and pepper
production. Both X perforans and
P.s. tomato are seed-borne, which
allows for the movement of strains on
a global scale. Both pathogens can
persist on tomato leaves without
causing symptoms.
4. Refrain from handling tomato plants
when foliage is wet to minimize the
spread of either bacterium in the
canopy and throughout the field or
5. Apply bactericidal pesticides as
necessary (refer to Table 1, Page 10).
When applying copper-based
bactericides, mix with mancozeb for
the control of copper resistant strains,
which are prevalent among both

Exclusion is the best tactic for the
management of bacterial speck and spot on
tomato. The goal of implementing field
rotations, destroying infected debris,
volunteers, and weeds, and using disease-free
tomato transplants is to minimize the amount
of inoculum in the field at the beginning of the
season. Refraining from field activities when
the plant canopy is wet and making timely
application of bactericides reduces the
movement of bacteria throughout the plant
canopy and field. Bactericides, like most
fungicides, are preventative by nature.
Unfortunately, even the best bactericidal
treatment offers only limited protection when
environmental conditions are favorable for
rapid disease development, especially during
periods of heavy, wind-driven rains, further
stressing the need to implement tactics that
exclude both pathogens.

Figure 1. Tomato plant exhibiting abnormal stem
lesions and extreme foliar blighting associated with
the bacterial speck outbreak in Immokalee, FL.
Photo credit: G. McAvoy.

Figure 2. Tomato
leaves exhibiting
symptoms of bacte-
rial speck (left) and
bacterial spot (right).
Note chlorotic halos
and angular nature
of bacterial speck
lesions. Photo
credit: G. Vallad

U: to-......

Figure 3. Tomato leaves with symptoms of bacte-
rial speck (left) and bacterial spot (right). Note
prominent chlorotic halos surrounding bacterial
speck lesions.
Photo credit: G. Vallad.

Figure 4. Fruit exhibiting symptoms of bacterial
speck (left) and bacterial spot (right). Photo credits:
J. Jones (left) and G. Vallad (right).

Table 1. Products labeled for the
management of bacterial spot and speck
on tomato. Ordered by FRAC group
according to mode of action. Be sure to
read a current product label before
applying any chemical. Page 10

Maximum Rate /
Acre / Min.
Fungicide I Days to
Chemical (active ingredient) Group' Applic. Season Harvest Remarks2
(copper compounds) Ml SEE INDIVIDUAL 1 Mancozeb enhances bactericidal
Many brands available: LABELS effect of fix copper compounds. See
Badge SC, Badge X2, Basic label for details.
Copper 50W HB, Basic Copper
53, C-O-C-S WDG, Champ DP,
Champ F2 FL, Champ WG,
Champion WP, C-O-C DF, C-O-
C WP, Copper Count N, Cueva,
Cuprofix Ultra 40D, Kentan DF,
Kocide 3000, Kocide 2000,
Kocide DF, Nordox, Nordox
75WG, Nu Cop 50WP, Nu Cop
3L, Nu Cop 50DF, Nu Cop HB
Cuprofix MZ Disperss M3 / M1 7.25 lbs 55.2 lbs 5 See label
(mancozeb + copper sulfate)

ManKocide M3 /M1 5 lbs. 112 lbs. 5
(mancozeb + copper hydroxide)

Tanos 11/27 8 oz 72 oz 3 For the suppression of bacterial
(famoxadone + cymoxanil) spot only. Do not alternate or tank
mix with other FRAC group 11
Agri-mycin 17 25 200 ppm For transplant production only.
Ag Streptomycin Many isolates are resistant to
Bac-Master streptomycin.
Fire Wall
(streptomycin sulfate)
Serenade ASO 44 See label See label 0 Mix with copper compounds, see
Serenade Max label for details. OMRI listed.
(Bacillus subtilis strain QST
Actigard (acibenzolar-S-methyl) P 0.75 oz 4.75 oz 14 See label for details.
Regalia SC P 1% (v/v) 6 apps. 0 Add a surfactant such as Nu-FilmP
(Extract of Reynoutria per year at 0.02% (v/v). Limit of 6 apps. per
sachalinensis) year. Do not apply in excess of 2
Qts/A 7 days prior to harvest. See
label for details.
AgriPhage NC 2 -0 See label for details. OMRI listed.
(bacteriophage) pts/100ga
OxiDate NC 1:100 -0 See label for details. OMRI listed.
(hydrogen peroxide) dilution
Sonata NC See label See label 0 Mix with copper compounds, see
Taegro label for details. OMRI listed.
(Bacillus sp.)
Trilogy NC See label See label 0 See label for details. OMRI listed.
(Neem oil)
'FRAC code (fungicide group): Numbers (1-44) and letters (M, NC, U, P) are used to distinguish the fungicide mode of action groups. All
fungicides within the same group (with same number or letter) indicate same active ingredient or similar mode of action. This information must
be considered for the fungicide resistance management decisions. M = Multi site inhibitors, fungicide resistance risk is low; NC = not classi-
fied, includes mineral oils, organic oils, potassium bicarbonate, and other materials of biological origin; U = Recent molecules with unknown
mode of action; P = host plant defense inducers. Source: FRAC Code List 2009; http://www.frac.info/ (FRAC = Fungicide Resistance Action
2Information provided in this table applies only to Florida. Be sure to read a current product label before applying any chemical. The use of
brand names and any mention or listing of commercial products or services in the publication does not imply endorsement by the University of
Florida Cooperative Extension Service nor discrimination against similar products or services not mentioned.

SNSV (formerly TSV) in
Catalina Moyer, Vance M. Whitaker, and Natalia A.
Peres, GCREC

It is well known to growers that much
of the stock of 'Florida Radiance' planted
during the 2009-10 season was virus-
infected. What is not so obvious is whether
or how much the presence of strawberry
necrotic shock disease (SNSV) in 'Florida
Radiance' impacted the performance of this
variety. So what have we learned from past
For many years, SNSV was thought
to be caused by a strain of tobacco streak
virus (TSV). However, a study published in
2004 found that strawberry necrotic shock
disease is caused by a different virus and not
by a strain of TSV. The name "strawberry
necrotic shock virus" (SNSV) was then
suggested for this virus instead of TSV, and
thus, the acronym SNSV is used hereafter.
SNSV apparently causes no
symptoms in commercial cultivars. Grafted
susceptible indicator strawberry plants
(Fragaria vesca) may show a severe necrotic
reaction in new leaves; however, these
symptoms are temporary, and the new
growth appears normal and healthy.
Depending on the virus isolate, symptoms on
the plant indicator may also include
chlorosis, stunting, and leaf malformation.
SNSV has been reported in the U.S.,
Australia, and Israel. Although commercial
cultivars are symptomless, reduction of yield
and runner production has been reported.
Dissemination of this virus occurs through
seed, pollen, or thrips. This virus has a wide
host range, and host plant species near
strawberry fields can serve as sources of
inoculum. The most practical way to
minimize the risk of infection on commercial
fields is to use clean plant material (tissue
cultured and virus tested) and to follow best
management practices for insect and weed

control. However, once this virus is within a
fruiting field, there is no means of control, as it
is transmitted by pollen.
At the end of the 2008-2009 strawberry
season, serological tests confirmed the
presence of strawberry necrotic shock virus
(SNSV) in research fields at the University of
Florida Gulf Coast Research and Education
Center (UF GCREC) and some commercial
strawberry farms. Cultivars that tested positive
for SNSV included 'Strawberry Festival',
'Sweet Charlie', 'Florida Radiance', and 'Florida
Elyana'. However, yields were not noticeably
different than those from previous years. Thus,
it was assumed these were new infections of
SNSV that were transmitted in Florida;
however, the hypotheses that the plants were
infected in the nurseries could not be dismissed
because plants were not tested early in the
During the 2009-2010 strawberry
season, leaf samples were collected from seven
cultivars and eleven nursery sources at three
times during the season. Samples from the UF
GCREC research fields in Wimauma and from
a selected grower's field in Dover were tested
for SNSV using the ELISA method. The first
samples were collected in November and
December to determine if plants were already
infected upon arrival from the nurseries.
Samples of 'Florida Radiance' from all nursery
sources grown at both locations tested positive
for SNSV. Only one nursery source was tested
for the other newly released cultivar, 'Florida
Elyana', and it was also found to be positive.
SNSV was not detected in samples of the
cultivars 'Strawberry Festival', 'Camarosa',
'Treasure', 'Camino Real', or 'Sweet Charlie'
from any of the sources tested. Samples from
the same plants were collected again during the
middle and end of the strawberry season to
determine if the virus was spreading through
the fields. The last sampling was conducted
during the first week of April. SNSV was
confirmed in 'Florida Radiance' from all
nursery sources and in 'Florida Elyana' from

the one source previously noted. In addition,
'Strawberry Festival' plants from two sources
were positive in the UF GCREC fields.
Despite the presence of SNSV in 'Florida
Radiance' in the grower's field since the
beginning of the season, yields did not seem
to be affected, and SNSV was not detected in
other cultivars planted nearby. This indicates
that transmission and infection by SNSV
does not progress rapidly in strawberry
fields. However, it is possible that the colder-
than-normal winter temperatures during the
2009-10 strawberry season may have
prevented a more rapid spread of SNSV.
There was some conjecture that the
bullet-shaped fruit produced by 'Florida
Radiance' early in the season was caused by
the virus, but this is extremely unlikely. It is
most plausible that this fruit deformity was
exacerbated by the unseasonably hot weather
early in the season. Planting this variety later
(after Oct 10th) may help avoid these
symptoms in the future.
There is no evidence that the
presence of SNSV in 'Florida Radiance'
caused a decrease in yield or any other
symptoms. However, since this virus can
spread within fields and since it could
possibly cause symptoms in combination
with another virus, caution should still be
exercised and material monitored closely in
nursery fields.

International Issues and Growing
Concerns for New Nematode
Problems In the Florida Strawberry
J.W. Noling1 and Alicia Whidden2
1 CREC, 2Hillsborough County Cooperative Extension

We got through another season and
we don't need to belabor how hot it was
early and how persistently cold it became
later. In addition to production levels near

half of what is typically observed, the death
and destruction caused by sting nematodes was
obvious in many fields. The damage observed
would likely have been higher if a warmer
season had prevailed. In addition to sting
nematodes, we also observed a number of
fields in which late season problems appeared
to be caused by or at least associated with root-
knot nematodes, presumably the northern root-
knot nematode, Meloidogyne hapla.
Meloidogyne hapla is referred to as the
northern root-knot nematode because it
commonly occurs in cooler environments. It is
however also found in the tropics and
subtropics, usually at cool and high elevations.
The nematode's host range is wide and
encompasses a diverse group of over 2,500
herbaceous plant species in approximately 500
genera, but does not include most grasses and
grains. Root galls induced by M. hapla are
usually small compared to the other root-knot
nematode species prevalent in in Florida. In
addition to galling, typical symptoms on
strawberry parasitized by M. hapla include
plant stunting, reduced runner production,
depressed yields, shortened life of the
plantings. Previous research has also
demonstrated the importance of secondary
infection caused by other disease pathogens
penetrating the root system via wounds, and
that these secondary invaders are often more
important than direct damage caused by root-
knot nematodes.
Meloidogyne hapla is a common
nematode pest of strawberries in the
northeastern United States where the nematode
reduces crown vigor and fruit yield oftentimes
without producing diagnostic aboveground
symptoms. This is not to say that in Florida,
above ground symptoms are always observed.
During the course of this past season we
recovered root-knot nematode from soil and
root tissue from a number of different fields.
Dramatic levels of decline were not always
evident. In one field, at season's end,
however, we observed strawberry plants

collapsing under drought conditions, which
were associated with high soil densities of a
Meloidogyne species (we did not confirm
species as M hapla). M. hapla is however
thought to be the only root species hosted by
In general, root-knot nematode can
only move relatively short distances in soil.
In most instances, they are spread into new
areas as hitch hikers in soil or on equipment
between fields or within infected plant
materials which are then transported great
distances and then planted to soil. The
presence ofM. hapla should be of concern to
us here in Florida since it is known to reside
within imported bare-root transplants and
because it has been demonstrated to over
summer readily and increase in number over
time on strawberries and other plant hosts.
Sanitation, accomplished by identifying and
eliminating M. hapla from planting stock is
probably the single most important nematode
management tactic. Rotation with nonhost
species has been reported to be effective,
although successful use of rotation requires
knowledge about the host status of a large
number of plant species, including a wide
variety of weeds. Previous research has also
identified a number of highly resistant
strawberry genotypes, and if needed, can
provide a readily exploitable source of
resistance to M. hapla.
In general, most plant-parasitic
nematodes are controlled by preplant
fumigation. We are fortunate that due to
routine soil fumigation, nematodes (sting or
root-knot) are typically not observed to be a
significant problem in Florida strawberry
except where problems of fumigant
misapplication occur. Other problems (which
we can only speculate at this moment) have
also occurred when infected transplants from
Canadian nurseries were set into fumigant
treated soils, which offer a very favorable
environment for the population increase of
the introduced root-knot nematodes. Greater

problems obviously can occur when soil
densities of endemic (resident) populations are
augmented by the addition of those nematodes
within infected root tissues on incoming bare-
rooted transplants from Canada.
We don't know if most Florida growers
are aware that the Telone products (Telone II,
Telone C-17, Telone C35, Inline, Telone EC)
will only be available for the next two growing
seasons in Canada. After November 2011,
these Telone products will no longer be
registered and will not be available for sale or
use in Canada. The loss of Telone in Canada
was ultimately decided by the manufacturer,
Dow AgroSciences, who simply decided the
Telone business in Canada was not big enough
to support product reregistrations costs
demanded by the Canadian government. The
question now becomes, What will Canadian
strawberry nurseryman do to manage
nematodes? The most immediate concern is
relying upon other less nematode effective
fumigants, which would then promote a
potential increase in numbers of nursery fields
and overall numbers of incoming nematode
infected transplants.
The use of certified planting stock (bare
-root transplants produced in fumigated fields)
combined with soil fumigation of fruiting
fields has been the primary management
technique for plant diseases, weeds, and
nematodes on strawberries. During the past 40
years, the use of soil fumigation had become
an accepted practice for many commercial
strawberry transplant producers in Canada.
The practice, particularly when methyl
bromide was used, greatly improved plant
growth and runner production. It also served
to minimize international transport of
nematode pests to various U.S. locations.
Currently, M. hapla is not considered a
"quarantine pest". Canada however must meet
US nematode requirements for potato cyst
nematodes as by USDA APHIS protocol 1-14
Nursery Stock Restrictions Manual 04/2010-36
PPQ. This manual effectively says that articles

for planting (except seeds, unrooted cuttings)
and articles collected from the wild, must be
accompanied by a phytosanitary certificate
containing an additional declaration that the
articles offered for importation were grown
on land that has been sampled and
microscopically inspected by the plant
protection organization of the country of
origin and found to be free from the potato
cyst nematodes Globodera rostochiensis and
Globodera pallida:
We will point out at this time that we
believe it is possible that the soil sampling
report that each Canadian nurseryman must
acquire for phytosanitary certification for
potato cyst nematodes could be expanded
voluntarily to include counts of Melodiogyne
hapla and other species if present. A
voluntary expansion of the USDA APHIS
phytosanitary certification program in
Canada to insure that fields are also M. hapla
free would offer some assurance to Florida
growers that the plants purchased from
certified growers are not only true to variety,
but apparently free from significant
nematode pests besides the potato cyst
It is not clear to us how widely
distributed M. hapla is in the Canadian
strawberry nursery industry. Specific
information on current nematode occurrence
in strawberry nursery fields in Canada would
be helpful for Florida growers who would
want to consider the risk of importing new
nematode problems into their fields,
particularly after the loss of Telone next year
in Canada. It is also not clear how widely
distributed M. hapla currently is in Florida
strawberry acreage. Further research and
surveys may be needed to determine the
significance of the problem, document
possible interaction with other soil pathogens
and the environment, and to determine the
role played by unsanitary imported
transplants in compounding nematode
problems for Florida growers. This survey

would provide important background
information for planning and administering
nematode management strategies in strawberry
fields in both Canada and Florida. It is possible
that in years to come, strawberry growers who
travel to Canadian nurseries to inspect
purchased plants may want to demand
phytosanitary inspection to include testing for
nematodes within nursery fields from which
runners have been grown prior to digging and
shipment to Florida. Without post plant
chemical measures, there remains no effective
means of managing nematode populations and
their damage once introduced.

Notes on Cultural Practices: Effects
of Shoot Pruning on Tomato Yield
and Bacterial Leaf Spot
Bielinski M. Santos and Gary E. Vallad

Bacterial Spot and Early Shoot Pruning
Bacterial spot is one of the most troublesome
diseases in tomato. This disease is caused by
several bacteria in the Xanthomonas genus and
it is favored by warm, humid weather
conditions, but often initiated by episodes of
wind-driven rain. On the leaves, infection
begins when the bacterium enters the plant
through natural openings and wounds where it
multiplies within plant tissues (Picture 1).
Within three to four days, the first symptoms,
water-soaked lesions, can be observed on
lower leaf surfaces. Lesions can enlarge and
coalesce causing extensive leaf chlorosis and
defoliation. All aboveground tissues are
susceptible to the disease, including fruit.
Control of bacterial spot relies on cultural
exclusion of the pathogen from production
areas, use of resistant cultivars, and diligent
application of copper-based bactericides. The
presence of infected tomato volunteers and
weedy hosts are common sources of local
inoculum. Infected seed and transplants are
also a mechanism of long distance movement.

The use of copper-based bactericides can
offer some level of control, except under the
most extreme weather conditions. A
dithiocarbamate (either maneb or mancozeb)
is routinely combined with copper-based
bactericides to enhance bacterial spot control,
but reduces the fungicidal activity of the
Most growers of round tomatoes in
Florida perform shoot pruning on their crops
during the early part of the growing season to
reduce the number of unwanted lateral
branches. This practice usually occurs
between 2 and 4 weeks after transplanting
(WAT) and it could be accomplished once or
twice during that period by removing shoots
from ground level up to the primary fork
below the first flower cluster. Previous
research showed that for some tomato
cultivars, shoot pruning increased early yield,
whereas other studies found no response or
reduced growth and yields. Some growers
and scientists think that shoot pruning could
be a potential practice to reduce bacterial
spot infection because: a) it reduces the
amount of foliage near the soil that could
serve as an initial point of entry for the
bacterium, and b) it changes architecture of
plant canopies thus changing air and
moisture flow through the leaves.
Additionally, shoot pruning costs about $50/
acre, which is a significant expense for
tomato production. The objective of this
study was to determine the effect of early
shoot pruning on the severity of bacterial
spot, and on the growth and yield of different
tomato cultivars.

Field Studies
Two field trials were conducted in the Spring
and Fall 2009 at the Gulf Coast Research and
Education Center of the University of Florida
in Balm, Florida, using standard tomato
production practices (e.g. soil fumigation,
mulching, drip irrigation). Tomato seedlings
in the four-true-leaf stage (8 inches tall) were

transplanted in single rows and 2 inches offset
of bed centers. Planting in-row distance was 18
inches. The study had the combination of two
tomato cultivars, two bacterial spot inoculation
regimes, and three shoot pruning programs.
The tomato cultivars were 'Tygress' and
'Security-28', which are resistant to the tomato
yellow leaf curl virus. Shoot pruning levels
were heavy and light, and a non-pruned
treatment was added. Light pruning was
defined as carefully removing by hand only
two to three lateral buds ("suckers") from the
main stems from ground level to 6 inches high,
whereas heavy pruning was defined as the
removal of all the lateral buds and stems up to
6 inches high. Early shoot pruning occurred
between 3 and 4 WAT. Bacterial spot
treatments consisted of non-inoculated plots
and plots inoculated with a suspension of X.
perforans strain XT4 (1 x 106 cfu/mL), which
was applied to the foliage with a conventional
backpack sprayer at 5 WAT at a volume of
approximately 15 mL per plant.
Plant heights were determined at 3 and 6 WAT
and tomato fruit were harvested twice (10 and
12 WAT) in the mature green stage and graded
following current market standards as extra-
large and marketable fruit of all categories.
Fruit yield from the first harvest (10 WAT)
were considered early fruit weight, while the
summation of the two harvests (10 and 12
WAT) was the seasonal fruit weight. For
bacterial spot, plots were monitored for disease
and rated for severity at 7 and 9 WAT in the
spring trial, and at 9 and 11 WAT in the fall
trial using the Horsfall-Barratt scale, a non-
dimensional 12 point scale, to assess the
percentage of canopy affected by bacterial leaf
spot. Disease severity values were converted to
mid-percentages and used to generate area
under disease progress curve (AUDPC).
Plant height and bacterial spot severity.
Shoot pruning did not affect tomato plant
height at 3 and 6 WAT, regardless of cultivars
and bacterial spot inoculation (data not
shown). Bacterial spot inoculation increased

disease severity based on AUDPC of 1445
(an average disease severity of 41%) in
inoculated versus an AUDPC of 821 (an
average disease severity of 29%) in non-
inoculated plots averaged across both
seasons (data not shown). Disease severity
was greater at the end of the spring trial in
comparison to the end of the Fall 2009 trial
(65% and 35%, respectively). Inversely,
initial disease severity was much greater in
the fall study (24% disease severity in non-
inoculated plots) than the spring trial (1.5%
disease severity in non-inoculated plots).
'Tygress' was more susceptible to bacterial
spot than 'Security-28', exhibiting 20.4%
more disease on average.
Early tomato fruit weight. Early extra
-large fruit weight was affected by tomato
cultivars and the inoculation of bacterial
spot, but not by pruning programs or the
interaction among factors. 'Security-28' had
the highest early extra-large fruit weight with
5.1 ton/acre, which was more than 2.5 times
higher than that obtained with
'Tygress' (Table 1). Tomato plants
inoculated with bacterial spot reduced their
extra-large fruit weight by 31% in
comparison with those non-inoculated with
the bacterium. Pruning programs resulted in
extra-large yields ranging between 3.4 and
3.6 ton/acre. Early marketable fruit weight
was influenced by the interaction between
cultivars and pruning programs, and
separately by the inoculation of bacterial spot
(Table 1). There were no differences on early
marketable fruit weight among the
combinations of'Security-28' and the three
pruning programs, which averaged 6.9 ton/
acre of fruit. At the same time, all pruning
programs in plots planted with 'Tygress' did
not differ among each other, while having
significantly lower marketable fruit weight at
10 WAT than the 'Security-28' and pruning
combinations. Tomato plants in plots
inoculated with bacterial spot decreased their

marketable fruit weight at 10 WAT by 25% in
comparison with the non-inoculated plants.
Seasonal tomato fruit weight. The
cultivar by bacterial spot inoculation
interaction affected the seasonal extra-large
fruit weight. However, other main factors and
interactions were not significant. The highest
seasonal extra-large fruit weight was obtained
in plots non-inoculated with bacterial spot and
planted with 'Security-28' (11.1 ton/acre),
followed by the combination of'Security-28'
and bacterial spot inoculation (Table 2). There
was no effect of the bacterial spot inoculation
on the seasonal extra-large fruit weight
obtained in plots planted with 'Tygress'. All
three factors individually influenced the
seasonal marketable fruit weight of tomato.
Non-inoculated plots produced 21% higher
seasonal yields (18.1 ton/acre) in comparison
with plants inoculated with bacterial spot (15.0
ton/acre). When comparing pruning programs,
there was no difference between light pruned
plants and the non-pruned control for seasonal
marketable fruit weight, regardless of tomato
cultivars (Table 2). However, heavy pruning
did reduce seasonal yields by 10% in
comparison with the non-pruned control.

These results indicated that light shoot pruning
did not improve tomato yield of total and extra
-large marketable fruit. At the same time, this
practice did not reduce bacterial spot severity
on 'Security-28' and 'Tygress' tomato leaves.
In contrast, heavy pruning reduced seasonal
marketable yields in comparison with non-
pruned plants. It is possible that other cultivars
may benefit from shoot pruning, as the tested
cultivars are newer hybrids introduced to the
market for their resistance to tomato yellow
leaf curl virus. Data also emphasized the
impact of bacterial spot on fruit production,
especially the production of early extra-large
fruit, and the importance of selecting varieties
with improved tolerance to bacterial spot when
disease pressure is high. By eliminating light

shoot pruning from routine cultural practices, tomato growers can save up to $50/acre, which
might translate into near $2 million per year in savings for all the planted areas in Florida.

Picture 1. Bacterial spot lesions on
the lower surface of tomato leaves
and a view of a severely-infected
tomato field (Credits: G.E. Vallad).

Table 1. Effects of early shoot pruning levels, tomato cultivars, and bacterial spot inoculation
on early extra-large and total marketable fruit weight. Spring and Fall 2009, Balm, Florida.

Eal eta-ag fut alymretbe ri


Pruning x cultivar

ton/acre ton/acre
Non-pruned 3.5 Non-pruned, 7.4 a
Light 3.6 Light, 'Security-28' 7.1 a
Heavy 3.4 Heavy, 'Security- 6.3 a
Significance NS Heavy, 'Tygress' 4.4 b
Cultivar Light, 'Tygress' 3.7 b
'Security-28' 5.1 a Non-pruned, 3.4 b
'Tygress' 1.9 b
Significance Significance *
(P<0.05) (P<0.05)
Bacterial spot Bacterial spot
Non-inoculated 4.2 a Non-inoculated 6.4 a
Inoculated 2.9 b Inoculated 4.8 b
Significance Significance *
(P<0.05) (P<0.05)
zValues followed by the same letter in the same column do not differ statistically at the 5% sig-
nificance level. NS and = non-significant and significant, respectively.

Table 2. Effects of early shoot pruning levels, tomato cultivars, and bacterial spot inoculation
on seasonal extra-large and total marketable fruit weight. Spring and Fall 2009, Balm, Florida.

Sesoa ie iex4tr-age Seasona maktal

Cultivar x bacterial spot


ton/acre ton/acre
Non-inoculated, 11.1 a Non-pruned 18.2 a
Inoculated, 'Security- 8.1 b Light 17.4 ab
Non-inoculated, 7.0 c Heavy 16.3 b
Inoculated, 'Tygress' 7.5 c Significance *
Significance (P<0.05) Cultivar
'Security-28' 18.3 a
'Tygress' 15.0 b
Pruning Significance *
Non-pruned 8.4 Bacterial spot
Light 8.3 Non- 18.1 a
Heavy 8.4 Inoculated 15.2 b
Significance (P<0.05) NS Significance *
zValues followed by the same letter in the same column do not differ statistically at the 5%
significance level. NS and = non-significant and significant, respectively.

Mark your calendars for the next Florida Ag Expo scheduled for Wednesday November 10,
2010. This year's expo will include a Growers Roundtable regarding -Current Issues Facing
the Vegetable Industry. In addition speakers will include the new Sr. Vice President of IFAS,
Dr. Jack Payne and Congressman Adam Putnam (schedule permitting). Other highlights will
include field tours, vendor shows and much more. Registration is always free and should be
available in the next few months at http://flaagexpo.ifas.ufl.edu
or call (813) 634-0000 for information.

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