Group Title: Berry/vegetable times.
Title: Berry/vegetable times. November 2003.
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Title: Berry/vegetable times. November 2003.
Uniform Title: Berry/vegetable times.
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Creator: Gulf Coast Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida
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Gulf Coast Research and Education Center
Publication Date: November 2003
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9. FLORIDA Berry/Vegetable Times

EXTENSION %P November 2003
imtiMute ot Food and Agracultural SceWnCm s .. 0 6

In this issue...
Crown Rots of Strawberry Page 2
Suppression ofTwospotted Page 3
Spider Mites
Ideas for Increasing Florida Page 4
Strawberry Growers' Profit
Magnesium Applications and Page 5
Bacterial Spot on Tomatoes
and Peppers
Now is the Time Page 5
Strawberry School Agenda Page 5

Cont etnsonOfieSefer Am

744-5519.TI PC!!I I~l~lg

Nov. 18 StawbrySho 03

From your E.\l'ii\in
Coming up this month we
have the Strawberry School 2003 on
November 18th from 9:00 till around
3:30 at GCREC-Dover. 1 CORE and
1 private applicator CEU and CCA
credits of 1.5 SW, 1.5 PM, and 1.0
CM have been granted. The
schedule appears on page 5 of this
newsletter. We have a variety of talks
from birds and freezes to water and
BMP issues and a demonstration on
how to calibrate your sprayer. Lunch
is being provided by Kenneth Parker
and Chemical Dynamics. We will be
having a question and answer session
on water and nutrition issues and ask
you to send your questions to Dr.
Duval ahead of time. He and Dr.
Simonne will be answering your
questions. Please e-mail questions to or mail them
to him at 13138 Lewis Gallagher Rd.,
Dover, Fl. 33527. Also please RSVP
to Christine Cooley at (813) 744-
6630 ext. 60 or by
Nov. 14 so we will have a headcount
for lunch. Come join us for a fun and
informative time.

This is a reminder for the
packinghouse folks that the deadline
to register their facility with the U. S.
Food and Drug Administration is
December 12, 2003. This is in
compliance with the new FDA
bioterrorism registration regulations.
This does not apply to farms.
Facilities may register online at For questions
you can call 1-800-216-7331 or
contact Courtney Hunt of the FDA in
Tallahassee at (850) 942-8325.

Happy Thanksgiving!
Alicia Whidden

"Budworms" can be an
Early Season Problem
Jim Price

As soon as crop establishing
overhead irrigation is removed from
strawberry transplants, growers must
divert their attention for the next
several weeks to the early-season
lepidopterous larvae ("worm")
problem. Growers often speak of the
problem critters as budwormss", but
the problem truly is not a single
worm but a mixture of two or three.
When we see worms this time of year
they are usually the corn earworm,
southern armyworm or the fall
armyworm and none of them carries
the name "budworm".
Each of these feeds on
tender strawberry leaf blades as they
develop from the strawberry bud and

The Institute oft Food and Agricultural 6Scienes (II ',P in t l hi l -mpliment Opportunity Athirmatie Action Employer authorized to provide Ttrtrch, educational
infonnation and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap or national origin.

A monthly newsletter of the University of Florida
IFAS, Gulf Coast Research and Education Center,
and Florida Cooperative Extension Service
Hillsborough Co Cooperative Ext Service
5339 CR 579, Seffner, FL 33584
(813) 744-5519 SC 541-5772
Editor Ahcia Whidden,
Director Mary Chernesky
Gulf Coast REC
13138 Lewis Gallagher Rd, Dover, FL 33527
http //gcrec ifas ufl edu
(813)744-6630 SC512-1160
Design & Layout Christine Cooley
Director JackRechcigl

Volume III Issue I I

Berry/Vegetable Times

Volume III Issue 11

cause the ragged appearance of
young, central leaves. This activity
proceeds near the bud of the
transplant yielding good cause for
the "budworm" name. The name
"budworm" sometimes is used in the
Florida strawberry industry for the
lesser cornstalk borer that produces
a dirty silken tube that extends from
the base of the crown to the soil.
This adds to the confusion. This
article is about the first three worms
and not about the lesser cornstalk
Scouts should include
budworms in their inspection routine
by searching, twice per week during
the early season, for young leaves
with holes and missing margins.
Dark, small fecal pellets on the tops
of leaves or on the plastic mulch
below leaves also indicate budworm
feeding. Eggs of the corn earworm
are laid alone, but armyworm eggs
are laid in masses. Remedial action
should be taken anytime budworms
are found at suspicious sites during
the scouting routine.
Several products are
available to control the infestation of
budworms and each should be
applied when the worms are small.
Lannate and the pyrethroids,
Brigade" andD..i i.I can be
effective, but they are broad-
spectrum insecticides that can kill
naturally occurring beneficial
parasites and predators. Once those
beneficial are removed from a field,
aphids, spider mites, worms, and
other pests can increase to cause
more problems. None of these
insecticides should be applied if
Phytoseiulus persimilis predators
have been released for spider mite
control or if the predators are to be
released within 3 weeks of a
Lannate application or 6 weeks of
a pyrethroid application.
SpinTor and formulations
of Bacillus thuringiensis can also be
effective and neither of these is as
hazardous to beneficial as are
Lannate and the pyrethroids.
These insecticides are compatible

with P. persimilis predators,
although repeated applications of
SpinTor may reduce the predator
population slightly.
It is important to recognize
and address the budworm problem
early in an episode. Once the initial
fall budworm problem is under
control, scouts can reduce
inspections to once per week and
growers can concentrate more on
spider mites and other pests certain
to come.

Crown Rots of Strawberry
Jim Mertely

Once strawberry
transplants are established and begin
growing rapidly, some plants may
wilt suddenly and die in a matter of
days. The crowns of these plants are
rotted internally and show decayed
areas that are brown, red, black, or
marbled in appearance. Several
fungi cause these symptoms,
including anthracnose fungi in the
genus Colletotrichum, and several
species of Phytophthora. However,
because the symptoms caused by
these fungi are not very distinctive,
the pathogen cannot be identified by
symptoms alone. In order to treat
crown rot diseases effectively, it is
necessary to know which pathogen
is responsible. Therefore, growers
are encouraged to submit samples of
collapsed plants to the strawberry
diagnostic lab before attempting to
correct the problem.

Berry/Vegetable Times

cause a typical form of crown rot
characterized by sudden collapse
and death of plants. At one time,
these pathogens were thought to
come from infected transplants.
This may have been true when
transplants were grown in local
nurseries; since both species have
been isolated from native Florida
plants. Molecular fingerprinting has
shown that C. gloeosporioides
isolates pathogenic to strawberry
come from the same population as
native local isolates. However,
neither species has been found on
Canadian nursery plants. Healthy
transplants become infected during
warm, wet periods in the fall by
spores produced on plants bordering
the berry field. Starting a disease
management program just after
watering-in may control this form of
Colletotrichum crown rot by
preventing early infections.
Programs based on captain or Thiram
should be effective for this purpose,
since both fungicides reduce
infections of the petioles and leaves.
Plants that are already infected may
benefit from one or two applications
of the systemic fungicide Topsin M,
according to preliminary data
collected by Dr. Dan Legard.

Crown rot
symptoms caused
by C.
gloeosporzozdes or
C. fragarae.

Crown rots caused by anthracnose
fungi can be divided into two types.
C. gloeosporioides and C. fragariae

Volume III Issue 11

Crown and root rot symptoms caused by C.

A second, atypical type of
crown rot is caused by C. acutatum.
Transplants are infected by this
pathogen in the nursery, and may be
difficult to establish in the
production field due to root necrosis
disease. In susceptible cultivars such
as Camarosa and Treasure, the
pathogen enters the crown from the
rotted roots, and produces a small
decayed area at the base of the
crown. Plants infected in this
manner often die, but may persist for
some time as new structural roots
develop from areas higher up on the
crown. There is little that can be
done for plants severely infected by
C. acutatum, but any practice which
reduces stress during establishment
may aid the recovery of mildly
infected plants.

Crown rot symptoms caused by,

Phytophthora species such
as P. cactorum and P. citricola cause
another typical type of crown rot.
Little research has been done on
Phytophthora crown rot under
Florida conditions, probably due to
the sporadic nature of the disease.
The origin of infections in our
farming system is unclear. However,
it is known that Phytophthora spp.
persist for long periods in the soil,
but are killed by soil fumigation.

Roots are infected by a swimming
spore called a zoospore. There are
two chemical strategies for
Phytophthora crown rot control. One
is preventative and involves the
application of Ridomil Gold through
the drip line. Due to the expense of
this product, one application is
usually made after watering in.
However, a second application can
be made up until fruit set if diseased
plants are found in the field. The
second strategy involves spraying the
foliage with Aliette (Bayer) or
Prophyte (Luxembourg Industries).
Both products contain phosphite, a
form of phosphorus fungistatic to
Phytophthora spp that is translocated
downward in the plant. While
phosphite fungicides are more
effective when applied
preventatively, they may also be of
some benefit when applied as soon
as the disease is found in the field.
Some foliar fertilizers contain
phosphite, but are not specifically
labeled for disease control. Finally,
cultural practices that prevent
excessive soil moisture may reduce
the number of successful infections
and plant mortality.

Suppression of
Twospotted Spider Mites
Oscar E. Liburd, Gisette G.
Seferina and David A. Dinkins

The twospotted spider mite,
Tetranychus urticae Koch, has been
recognized as the most important
arthropod pest in strawberries in the
southeast. Twospotted spider mites
attack strawberries in the nursery,
greenhouse and commercial fields,
feeding on leaves causing yellowing,
which ultimately leads to a reduction
in yield. Traditional control
strategies for twospotted spider mites
have required several applications of
key acaricides during a typical
strawberry production season. In
many cases, miticides have been
applied as a preventative measure or

Berry/Vegetable Times
on a calendar basis, resulting in high
control costs and the development of
resistance. As an alternative to
chemical control, some growers have
focused on inoculative releases of
predatory mites.
In Florida, the predatory mite
that has been released most often has
been, Phytoseiulus persimilis Athias-
Henriot. However, its establishment
has only been successful in the
southern regions of the state
(Hillsborough County). Several
theories have been suggested as to
the reasons why this predatory mite,
P. persimilis, has not been successful
in northern Florida and other areas in
the southeast. It is generally
believed that P. persimilis is unable
to survive the north Florida winters.
As an alternative to P. persimilis, we
studied the predatory mite,
Neoseiulus californicus McGregor to
determine its effect on twospotted
spider mite reproductive rates and
their overwintering capabilities in
north Florida.
A 5-acre strawberry field in
Bradford County (northern Florida)
was selected for our test site where
previous releases of P. persimilis had
been unsuccessful. The predatory
mite, Neoseiulus californicus
McGregor, was chosen because it
has provided fairly good control of
twospotted spider mites in other
areas of the country. This predatory
mite was released during the last
week of October at a rate of one
predator per strawberry plant.
During this time, the population of
twospotted spider mite averaged 5
mites per trifoliate. Standard routine
practices as far as disease
management were followed. The
grower was asked to reduce the use
of the conventional fungicidal
products; Sulphur and Captan
(Captec 4L). With regards to insect
management, the grower was asked
to avoid Lannate (Methomyl) and
Thiodan (Endosulfan). These
requests were made in light of
previous reports which indicated that
these pesticides are toxic to
predatory mites.

Volume III Issue 11 Berry/Vegetable Times

Our results indicated that N.
californicus provided excellent
control of twospotted spider mites
(Fig. 1). One week after release,
there was a significant reduction in
the number of twospotted spider mite
motiles and eggs. This reduction
continued until early December (Fig.
1). After that time, the average
temperature in northern Florida
remained low (- 60- 70s F daytime
high) until late January when the
temperature rebounded (>80s0 F
daytime high). Twospotted spider
mite activity increased significantly
in February. During that month, a
single application of AcramiteTM
(Bifenazate) was made to suppress
high populations of twospotted
spider mites and to avoid economic
damage resulting from spider mite
injury. After the application of
AcramiteTM, populations of N.
californicus increased rapidly further
suppressing the activity of
twospotted spider mites until the end
of the seas on.
Neoseiulus californicus has
shown traits of being a generalist
predator. These predators feed on
twospotted spider mites, thrips and
pollen but not on the strawberry
plants. Therefore, N. californicus

can survive in fields when
populations of twospotted spider
mites are low. They generally take a
longer time (compared with P.
persimilis) to suppress populations of
twospotted spider mites. There also
are reports thatN. californicus is
more susceptible to pesticides than
P. persimilis. In our laboratory, the
activity of N. californicus and P.
persimilis decreased significantly
after exposure to various pesticides.
However, both species recovered
from pesticide exposures after 48
This study was a one-year
on-farm demonstration that was
conducted in Bradford County
during the fall of 2002 and spring of
2003. Growers who are thinking of
adopting the use of N. californicus
should exercise caution because it is
customary to repeat studies for two
years before firm conclusions can be
drawn. Neoseiulus californicus can
be obtained from several sources
which are available on the internet.
For more information regarding this
on-farm demonstration trial you can
contact Dr. Oscar E. Liburd at (352)
392-1901 ext. 108 or you can log
onto http://FruitnVegIPM.ifas.ufl.

*TSM MolIles Unileated Plot
*TSM Eggs Untreated Plot
ITSM Maliles + Eggs Treated Plot

Sri Ilo-I
% 12D


Ideas for Increasing
Florida Strawberry
Growers' Profit
Craig Chandler

This two-part article
describes how research and
development efforts may help
Florida strawberry growers increase
their profit in the future. My
comments are organized around the
three main factors that affect
profitability: 1) production costs, 2)
yield of product, and 3) price of
product. Production costs are the
focus of this month's article, while
my thoughts on yield and price will
be presented in the December
One way to increase profit
is to reduce the cost of production,
which has been rising steadily in
recent years. So what are the major
costs of production, and how can
they be reduced? According to the
latest figures from the IFAS Ag
Business Center the top four pre-
harvest costs are transplants ($1700/
acre), fungicides ($717/acre), soil
fumigant ($684/acre), and
insecticides ($5 57/acre).
Considering transplants
first, what if we developed a cultivar
that could be successfully propagated
here in Florida? Currently, most
transplants are obtained from
nurseries that are over 1000 miles
from the state. Transportation
expenses for such a long haul must
add significantly to their cost. In
addition to being less costly, Florida
propagated plants may be easier to
establish. They could be dug from
the nursery one day, and planted in
the fruiting field the next. Crown rot
(caused by Colletotrichum
gloeosporioides) can be a serious
problem with locally propagated
plants (See Jim Mertely's article on
crown rots), but diseases caused by
C. acutatum may be less prevalent on
plants propagated in Florida than on
those propagated in cooler northern
climates. Local transplants may also

Response of Twospotted Spider Ites (TSM) to the Predatory MHe
Neasihws caMfiomicn in Bradford Countly Florida (202 2003)

Volume III Issue 11

Berry/Vegetable Times

Volume III Issue 11

be freer of angular leaf spot and
spider mites than ones from northern
nurseries. University of Florida Ph.
D. graduate student Steve
MacKenzie is currently conducting
fundamental research on C.
gloeosporioides -- research that
could bring us a step closer to being
able to propagate healthy strawberry
plants in Florida. In inoculation
studies at GCREC-Dover over the
last two seasons, 'Treasure' has
shown good resistance to several
isolates of C. gloeosporioides and
may be a logical candidate for a local
nursery trial. (Note: 'Treasure' is a
patented cultivar, and cannot be
propagated legally without a license
to do so.)
Moving on to fungicides,
what if growers could apply
fungicides based on cultivar, the
crop's stage of growth, and
environmental conditions, rather
than relying on fixed calendar
schedules? This sort of
sophistication could reduce product
and application costs without
compromising disease control. Dr.
Jim Mertely of GCREC-Dover has
been conducting research with this
idea in mind, and developed some
initial recommendations for
modifying the traditional spray
Opportunities to lower the
cost of soil fumigant are probably
going to be more limited than with
foliar fungicides. But growers may
be able to lower expenses by using
materials and rates based on actual
pre-plant pest populations. For
example, if sting nematode
(Belonolaimus longicaudatus) and
weed populations are relatively low
the grower may be able to use less
To keep insecticide (and
miticide) costs to a minimum, these
materials should be applied only
when needed which is sometimes
difficult to determine. Accurate
scouting reports and economic injury
thresholds (developed through
scientific research) are the tools
necessary to make informed pest

management decisions.
It must be pointed out, at
this point, that to reduce chemical
control costs and still maintain
effective disease and pest control
will, in most cases, require growers
to increase the amount of money
spent on management and
monitoring efforts.
In conclusion, I want to
emphasize that some of the ideas
mentioned above need to be tested
and refined before they can become
standard practices in commercial
strawberry production here in
Florida. But with industry support,
research and development efforts on
these topics will yield a more
profitable harvest for Florida
strawberry growers.

Magnesium Applications
and Bacterial Spot on
Tomatoes and Peppers
Phyllis Gilreath
Manatee Vegetable Newsletter,
Sept/Oct 2003

There have been questions recently
regarding the interaction of Mg
applications on the severity of
bacterial spot on tomatoes and
peppers. This is based on work
conducted several years ago by Dr.
Jeff Jones and others. In that study,
bacterial spot on inoculated plants
was more severe in leaves with high
levels of Mg. Foliar application of
Mg had a pronounced effect on
disease development, possibly
through the increase in available Mg.
(Mg has been shown to be essential
for the growth of bacteria.) In earlier
studies, pepper plants with Mg levels
at the upper end of the normal range
had considerably more disease than
plants with levels at the lower end of
the normal range. Some growers are
questioning the potential risk of
increasing bacterial spot severity by
applications of foliar nutritional
sprays containing Mg. Perhaps a
more pertinent question to be asking
is why these applications are being

Berry/Vegetable Times
made in the first place, unless there
is a documented Mg deficiency.
Most growers lime annually, usually
at least in part with dolomite, thus
Mg levels should be adequate. These
results would suggest that caution
should be exercised in foliar feeding
of peppers and tomatoes ii I !,
especially during periods of high
disease pressure.

Now is the Time
John R. Duval

Now is the time to start
fertilizer and water management. In
research done by Albregts and
Howard, it was found that delay of
fertigation and drip irrigation after
establishment could significantly
reduce early yields. Monitoring of
soil moisture and beginning a
fertilizer management quickly after
establishment is imperative. It must
also be remembered that while a 'full
grown' strawberry transplants soil
moisture threshold for optimum
performance is around 12-15
centibars, this is assuming a plant
with a well-developed root system.
Newly established transplants do not
have an extensive root system so
instead of 2-3 water applications a
week, smaller daily applications may
be necessary. This limited root
system also does not inhabit a great
deal of soil volume. Thus, when you
fertilize, do not over water so that
soluble nutrients (mainly nitrogen)
move downward out of the root
zones of young plants. It should also
be remembered that you cannot
'catch up' on missed fertilizer
applications. If the fertilizer is
lacking during critical growth
periods, adding additional fertilizer
later will not bring the plants to
where they would be if the
application had been made on time.
Therefore, to maximize strawberry
yields and monetary returns, an
active fertilizer and water
management strategy needs to be
implemented immediately after

Strawberry School 2003
Tuesday Nov. 18,2003
9:00 am-3:30 pm
13138 Lewis Gallagher Road, Dover

9:00 Welcome by Dr. Jack Rechcigl, Center Director of GCREC-Bradenton & Dover

9:10 "Bird Dispersal at Farms" by Larry Brashears, USDA Wildlife Services, Ruskin

9:40 "What you need to consider when using water for frost protection" by Dr. Larry Parson,
Lake Alfred REC

10:10 Winter Weather Program by Chris Oswalt. Citrus Extension Agent, Polk and

10:30 Break

10:50 "Drip System Management" by Alicia Whidden, Veg. Crops Extension Agent,
Hillsborough County.

11:10 "Building a BMP Plan for Strawberries-Where do we start? by Dr. Eric Simonne,
Horticultural Sciences, UF.

11:40 "Irrigation Scheduling & Monitoring" by Dr. John Duval, GCREC-Dover.

12:10 LUNCH Provided by Kenneth Parker of Chemical Dynamics

1:10 "Tail Water Recovery in Strawberries" by Dr. Craig Stanley, GCREC-Bradenton.

1:40 Sprayer Calibration by Doug Thompson, Chemical Containers

2:40 Questions and Answers on Water and Nutrition

RSVP by November 14
to Christine Cooley (813) 744-6630
or email


Volume III Issue I I

Ben-y/Vegetable Times

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