Group Title: Berry/vegetable times.
Title: Berry/vegetable times. November 2004.
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Title: Berry/vegetable times. November 2004.
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
Publisher: Gulf Coast Research and Education Center, University of Florida
Gulf Coast Research and Education Center
Publication Date: November 2004
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Bibliographic ID: UF00087388
Volume ID: VID00030
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Berry/Vegetable Times


UNI VERSITYOF

^"O'FLORIDA

EXTENSION
LslStiLuL; crErd a0d AorluiulLurt] SdncriEs


In this issue...
Post-transplanting "Clean-up" Page 2
Sprays

Plant Pathology Research Work Page 2
for 2004-05

Using Predatory Mites in Page 3
Strawberries This Season
Resistance of Selected Page 4
Strawberry Cultivars to
Anthracnose Fruit Rot and
Botrytis Fruit Rot
Physiology Research Work for Page 5
2004-05
Strawberry transplant size is Page 6
correlated with early season
yield




















A monthly newsletter of the University of Florida
IFAS, Gulf Coast Research and Education Center
and Florida Cooperative Extension Service
Hillsborough County Cooperative Ext Service
5339CR579, Seffner FL 33584
(813) 744-5519 SC 541-5772
Alicia Whidden Editor Mary Chernesky,
Director
Gulf Coast Research and Education Center
13138 Lewis Gallagher Road, Dover, FL 33527
(813)744-6630 SC 512-1160
Christine Cooley, Layout and Design
Jack Rechclgl, Director


From Your Extension
Agent ..

Good News for Pesticide License
Holders!
Recently some rule changes
were made to the laws that effect
licensed pesticide applicators. If you
renew by Dec. 31, 2004 the
requirement is a total of 8 continuing
education units (CEUs). Of that 8, a
minimum of 2 must be core CEUs
and you can have up to 4 core that
will count towards the total of 8
CEUs. The balance need to be in
your license category which for most
of you is private applicator
agriculture. The law was to change
on January 1, 2005 to a total of 12
with 4 of that required to be core
CEUs. License holders have gotten
lucky! Changes to the law became
effective September 17,2004 and the
total number of CEUs that a private
applicator pesticide license holder
will be required to have to renew
their license after January 1, 2005
will stay the same. After January 1,
2005 when you renew under the new
law you will need a total of 8 CEUs
and 4 of that must be core CEUs.
There are several ways to
earn core CEUs. You can attend
meetings offering core CEUs or look
for the core articles being published
in Citrus and Vegetable magazine.
Chemical companies are sponsoring
publication of articles on core
subjects in Citrus and Vegetable.
Each article has a set of questions
that you must answer for credit.
Contact the author to request the
questions, read the article and answer
the questions and mail to the author.


If you answer correctly you will
receive 1 core CEU. This is a great
way to get those 4 core CEUs you
need especially if your renewal date
is not far away. Please be sure and
thank the sponsors of the articles as
this would not be possible without
their generosity.
Another change to the law is
in recordkeeping. Now the starting
and ending time of spraying a
restricted use pesticide is required.
This replaces the general time of
application that you were able to use
in the past.
So remember if your license
renewal is after this year, you now
will need 4 core CEUs and 4 private
applicator CEUs. Also put down the
beginning and ending time of
spraying restricted use pesticides in
your records.
A Worker Protection
Standards (WPS) Train-the-Trainer
has been proposed for the early part
of December to be held at the
Hillsborough County Extension
Office in Seffner. If you are
interested please contact me at the
office (813) 744-5519 or email
AJWhidden@ifas.ufl.edu and if there
is enough interest we will hold the
class.

Happy Thanksgiving!
JAicia 2z idden


IFAS is an Equal Employment Opportunity Affirmative Action Employer authonzed to provide research, educational information and other services only to individuals and institutions that
function without regard to race, color, sex, age, handicap, or national origin U S Department of Agnculture, Cooperative Extension Service, University of Flonda, IFAS, Florida A & M
University Cooperative Extension Program, and Bloards of the County Commissioners Cooperating


Berry/Vegetable Times

November 2004


5 *Vr.


November 2004









Berry/Vegetable Times


Post-transplanting
"Clean-up" Sprays
James Price and Curtis Nagle

Inspections of shipped
strawberry transplants often reveal
spider mites, aphids and sometimes
armyworms or their eggs that
survived from cool climate nurseries.
Inspections of shipments before
transplanting and early field scouting
should be performed to detect such
problems and control measures may
be indicated when they are found.
Some growers apply a broad-pest-
spectrum clean-up spray soon after
the overhead watering has ended.
These early-season sprays
are not subject to some of the
concerns that exist for them later in
the season. For instance, the impact
of lingering residues that could
damage some natural predator and
parasite populations is minimal
because so little of the mature
canopy is present at the time of
application. Additionally, fewer
natural predator and parasite
colonies exist to be disrupted at this
early stage of the crop.
There are three popular
insecticides that growers normally
include in the clean-up sprays to
control some of the insects,
including aphids and armyworms,
that may accompany transplants.
Few of them are reliable in
controlling mites. There are some
important points for growers to
consider in choosing among these
three insecticides and they are
presented below.
One common clean-up
insecticide is Brigade (bifenthrin).
Brigade is a pyrethroid and should
not be used if Phytoseiulus persimilis
predator mites will be released in the
next several weeks.
Another one is Lorsban
75WG9 (chlorpyrifos) that
possesses "Florida only" FIFRA 2
(ee) supplemental labeling
permitting its use for armyworms
and aphids on strawberries. Lorsban
is a pre-bloom organophosphate and


cannot be applied after berries start
to form. That means if it is to be
used in the Plant City area, the use
must occur immediately after the
overhead irrigation ends. This
product is the least problematic, of
the three clean-up insecticides
mentioned here, for an impending
release ofP. persimilis predator
mites.
The last commonly used
clean-up insecticide is Lannate
(methomyl). Lannate is a carbamate
and should not be used within about
3 weeks of a release of P. persimilis
predator mites.
Other insecticides
sometimes are applied along with the
above three. Miticides may be
chosen, in addition to these common
clean-up insecticides, to bring
accompanying spider mites into
check.




Plant Pathology
Research for 2004-05
Natalia Peres

The 2004-05 strawberry
season promises to be a busy one for
the plant pathology group. To date,
we have a total of ten experiments
planned. As in past years, fungicides
will be evaluated for control of
Botrytis fruit rot (Botrytis cinerea),
anthracnose fruit rot (Colletotrichum
acutatum), and powdery mildew
(Sphaerotheca macularis) as well as
colletotrichum crown rot (C.
gloeosporioides). A dip experiment
will also be conducted to evaluate
the effect of fungicides on
establishment and control of root rot
(C. acutatum). Additionally, the
potential effect of fungicides applied
at different times prior to harvest
will be evaluated for the appearance
of gray mold in storage (after
harvest).
In another experiment short
and long infection periods (i.e., short
wetness and long wetness) will be
simulated to induce symptoms of


anthracnose fruit rot. The effect of
contact and systemetic fungicides to
control the disease after the infection
has been established will be
evaluated. Commercial cultivars and
advanced selections will also
continue to be evaluated for
susceptibility to Botrytis fruit rot and
anthracnose.
Additionally, offspring
from a cross between parents
susceptible to and resistant to
anthracnose fruit rot will be
evaluated to gain a better
understanding of the inheritance of
resistance.
An experiment has been
implemented in cooperation with Dr.
Jim Gilreath to test four different
fumigants applied through drip
irrigation as an alternative to methyl
bromide for the control of soilborne
pathogens
And, lastly, an experiment
in cooperation with Dr. John Duval
is being conducted to determine if
certain post-emergence herbicide
practices can result in fruit
malformation.
In order to be able to
conduct and evaluate these trials, a
new lab assistant, Catalina Torres,
has been hired. Catalina has a BS
degree in agricultural science and
joined our group just in time for the
new season.


Catahna Torres joins the plant pathology
program.


November 2004









Berry/Vegetable Times


Using Predatory Mites
in Strawberries This
Season
Silvia Rondon, Daniel Cantliffe, and
James Price

The twospotted spider mite
(TSM), Tetranychus urticae, is the
key pest affecting commercial
strawberry production in Florida
(Fig. 1). Traditionally, control
strategies for TSM relied on several
applications of miticides during the
strawberry production season which
resulted in high control costs and the
development of resistance.
Biological control, which involves
the use of beneficial arthropods to
control pests, is a viable alternative
for a sustainable strawberry
production system.
Phytoseiulus persimilis has
been the main predatory mite
released in Florida and other
strawberry production areas (Fig. 2).
'Persimilis' establishment has been
successful in the central and southern
regions of Florida, but in the
northern areas of the state has failed
to establish effectively (unpublished
data). Neoseiulus californicus is
another predatory mite species that
has been released sporadically
throughout Florida (Fig. 3);
however, its establishment and
potential beneficial activity has not
been documented. In the 2003-2004
strawberry season, Jim Price, Oscar
Liburd, Silvia Rondon, Dan
Cantliffe, and Norm Leppla from the
University of Florida, and Roger
Francis and Merle Shepard from
Clemson University, conducted on-
farm trials in collaboration with
growers, extension agents, and crop
consultants to demonstrate the
benefits of using both predatory
mites for TSM control. Similar
experiments are being repeated now.
The use of trade names in thispublication is solely
for the purpose of providing specific information.
It is not a guarantee or warranty of the products
names and does not signify that they are approved
to the exclusion ofothers ofsuitable composition.
Use pesticides safely. Read andfollow directions


Fig. 1. Heavy infestation oftwospotted spider
mites adults and eggs. Credit: S.I Rondon,
UF/IFAS.


Fig. 2. :F r ...... ,',r.. ., '... Credit: S.I.
Rondon, UF/IFAS.


In each farm, treatments
included two predatory mite species
(i '/ i. .,,. ,'i,, persimilis and
Neoseiulus californicus) and a
chemical miticide control. The
grower standard program acted as a
control for comparisons with
predatory mite treated areas. One
hundred leaflets per treatment,
collected randomly from each
treatment, were sampled weekly.
The undersurfaces of leaflets were
examined for the presence of TSM
with the aid of a 14 X lens. Predatory
mites were released at a rate of 1
predatory mite per strawberry plant
when approximately 10% of the
leaves were infested with TSM
(motiles and/or eggs) (Fig. 4). If
populations of TSM exceeded 10 %
before predatory mites had been
released, a low-risk miticide
(Acramite or Vendex) was sprayed
at the recommended rate to reduce
the TSM population.


Fig. 3. Neoseiulus californicus. Credit: S.I. Fig. 4. predatory mites in the
Rondon, UF/IFAS. strawberry crop. Credit. S.I.Rondon, UF
IFAS.


On-farm demonstration trials
were conducted in three regions in
the southeastern U.S., (1) central
Florida (Citrus and Hillsborough
Counties), (2) northern Florida
(Bradford and Duval Counties) and
(3) Charleston, South Carolina.
In central Florida, on-farm
trials were conducted in two fields of
cooperating growers at Floral City
(Citrus County), and Balm
(Hillsborough County), FL; a third
farm located at the University of
Florida Dover Research Station
(Hillsborough County) also was
included.


Preliminary results from
these trials indicated that it takes
approximately 2 to 3 weeks for
either predatory mite to get
established. During the 2003 -2004
season, strawberry transplants from
most nurseries arrived with less
than usual TSM problems. At our
location in Floral City, good results
were observed for TSM control on
young transplants by applying
Brigade (bifenthrin) pyrethroid
plus Diazinon (organophosphate)
immediately after transplant (last
week of October). The effectiveness
of Brigade and Diazinon plus the


November 2004








Berry/Vegetable Times


cold weather resulted into a low
density of TSM from November
through early February. Both
predators were released on February
26 at a rate of one predatory mite per
plant when TSM population reached
12 %. Predatory mites established in
the crop approximately 3 weeks after
release. In the grower standard
program, no additional miticides
were applied. Harvest continued
until the first week of April. By the
end of March, 'Persimilis had
reduced the TSM population
approximately 10%; however, by the
time 'Californicus' was established,
the season was essentially over. At
the Balm site, TSM infestations were
very spotty throughout the
experiment. 'Persimilis' was
released on December 16, while
'Californicus 'was released February
26. In Dover, TSM densities
remained at an unusually low level
the entire season, perhaps as a result
of a cooler than average winter.
'Persimilis' was released on
December 9 (at about 13% average
spider mite infestation) and
'Californicus' was released on
December 23 (at about 5%
infestation). TSM levels were at
about 5% infestation in both
predator areas on 25 February.
Thus, the use of low-risk
miticides in combination with
properly timed releases of predatory
mites should provide adequate
control of TSM throughout the
season. Discussion and detailed
results of the on going trials will be
available in future issues of Berry/
Vegetable Times. We would like to
thank Al Herndon (Ferris Farm) and
Cammy Hinton (Hinton's Farm) for
their collaboration. Also thanks to
Koppert who provided us with the
predatory mites. If you have any
questions please contact Silvia
Rondon. (srondon(&Smail.ifas.ufl.edu).


Plant Physiology
Research for 2004-05
Elizabeth Golden and John Duval

The Nitrogen/Irrigation
strawberry trial is in its final season.
This trial is being conducted in
collaboration with Dr. Eric Simonne.
The study examines 'Festival', FL
97-39, and 'Ventana' to determine if
IFAS recommendations could be
refined to take into account plant
type (i.e., small, medium or large
canopy). Specifically, the trial seeks
to determine for each of these
cultivars what amount of water and
fertilizer results in the highest
marketable yield.
Transplant research
continues with nurseries in Nova
Scotia. We have established a trial to
determine the effect of applying
CaNO3 to the nursery four weeks
before digging. The hypothesis
being tested is that nitrate levels in
the plant can be increased prior to
digging, and these higher levels will
increase the initial vigor of the plants
after establishment in the fruiting
field.
'.I! in.i'.r, crop protectant
is being tested for its effectiveness
to reduce heat stress on transplants.
The main ingredient in Surround is
Kaolin, a fine white clay. Beds were
sprayed with Surround before
planting. This treatment is similar to
whitewash on beds but Surround
washes off so that the benefits of the
black plastic are available when
temperatures drop. Surround was
also sprayed on top of some plants
when overhead irrigation concluded.
Daily soil temperatures during
establishment and harvest data will
be recorded.
In the vegetable area,
biological supplements are being
tested to see if they have the ability
to reduce fertilizer needs and
increase yield in broccoli.
NaturizeTM and Behold are liquid
supplements containing beneficial
soil microbes. 150 ml of Naturize,
Behold or water were applied to


planting holes as plugs were set.
100% or 70% of the amount of
fertilizer recommended by IFAS will
be supplied weekly. Plant size and
harvest dates will aid in determining
functionality of products.


Trial to evaluate Surround@ crop protectant.


Resistance of Selected
Strawberry Cultivars to
Anthracnose Fruit Rot
and Botrytis Fruit Rot
Craig Chandler, Jim Mertely, and
Natalia Peres

In Florida, Botrytis fruit rot
(caused by Botrytis cinerea) and
anthracnose fruit rot (caused by
Colletotrichum acutatum) are the
most important pre-harvest fruit
diseases on strawberry.
Environmental conditions conducive
to the development of Botrytis fruit
rot occur every year in Florida,
whereas conditions conducive to the
development of anthracnose fruit rot
occur more sporadically. When they
do occur, however, losses can be
severe. Fungicides are applied
regularly to control or delay the
onset of these diseases. Chemical
control recommendations (i.e.,
product, rate, and frequency) have
not traditionally incorporated
knowledge of cultivar resistance, but
this is beginning to change (See
"Strategies for early season disease
control" in July/Aug. Berry/
Vegetable Times Newsletter).
Knowing the resistance or


November 2004









Berry/Vegetable Times


susceptibility of a cultivar to B.
cinerea and C. acutatum may allow
us to develop cultivar specific
recommendations. This should
result in reduced fungicide use or
improved disease control. This
article summarizes the results of a
three-year study to assess fruit rot
resistance of cultivars of interest to
Florida growers.
Twin field trials were
established at the Dover research
center during the 2001-02, 2002-03,
and 2003 -04 seasons: one for the
determination of anthracnose
resistance and the other for the
determination of Botrytis resistance.
In the anthracnose trials,
distinct levels of resistance were
apparent (Table 1). 'Sweet Charlie'
and 'Carmine' were the cultivars
most resistant to anthracnose. The
incidence of anthracnose fruit rot in
'Sweet Charlie' averaged 4% over
three seasons, while 'Carmine', a
new cultivar from the University of
Florida, averaged 10% over two
seasons. 'Festival' was intermediate
in susceptibility to the disease,
averaging 36% incidence (three
seasons). 'Camarosa' and 'Treasure'
were highly susceptible, averaging
78% incidence (three seasons) and
89% incidence (two seasons)
respectively.
In the Botrytis trials, there
were fewer statistical separations
between cultivars than in the
anthracnose trials, due primarily to a
narrower range of disease incidence
among cultivars. In 2002, the
difference between cultivars with the
highest and lowest incidence of
Botrytis fruit rot was only 13%
(Table 2). Nevertheless, 'Camarosa'
and 'Carmine' had statistically lower
incidences of Botrytis fruit rot than
'Sweet Charlie'. In 2003, when the
range of disease incidence was even
lower (5%), 'Carmine' had less
Botrytis fruit rot than 'Festival' and
'Sweet Charlie'. In 2004, when
disease pressure was high,
'Camarosa' had a statistically lower
incidence of Botrytis fruit rot than


'Sweet Charlie'.
The Bo
somewhat comp
adequate control
rot in certain cul
and 'Treasure' h
of anthracnose f
to four applicati
(azoxystrobin).
plots of these tw
established with
infected with C.
nursery.


Table 1. Incider
fruit rot during
in February and
and 2004.



Cultivar

Camarosa
Camino Real
Carmine
Festival
Gaviota
Sweet Charlie
Treasure


itrytis trials were
promised by a lack of
I of anthracnose fruit


Workshop on Vegetable
BMP Manual


tivars. 'Camarosa The Florida Department of
ad >15% incidence Agriculture and Consumer Services,
ruit rot, despite two Office of Agricultural Water Policy,
ons of Abound@ is hosting a rule development
We suspect that workshop on December 7 at the
o cultivars were Hillsborough County Cooperative
plants latently Extension Service to share their draft
acutatum in the Vegetable and Agronomic Crop Best
Management Practices (BMP)
manual with area growers. This is
an important workshop because
ice of anthracnose state law requires that the BMP
S4-to-5 week period manual be adopted by rule under
March 2002, 2003, Florida Administrative Code, and the
manual then becomes the vehicle by
which growers can comply with
% Anthracnose emerging water quality requirements
2002 2003 2004 under Florida's Total Maximum
Daily Load program. Please make
75 76 83 plans to attend this meeting that
50 begins at 2:00 p.m.! Access to the
manual online is at:
10 9 www.floridaagwaterpolicy.com
29 47 31 under Best Management
Practices The web site also have
55 information on TMDLs and other
2 8 1 water quality and BMP issues.
Pesticide CEU's have been applied
96 81 for.


Table 2. Incidence of Botrytis fruit
rot during a 4-to-5 week period in
February and March 2002, 2003, and
2004.

% Botrytis


Cultivar


2002 2003 2004


Congratulations to Camille
Esmel, graduate student with John
Duval Plant Physiology program.
Cami completed her defense for her
Masters Degree and will continue
her studies with Jim Gilreath in soil
and weed science while working
towards her PhD. Good job Cami!


Camarosa 6 4 17
Camino Real 26
Carmine 7 2 -
Festival 9 6 25
Gaviota 2 -
Sweet Charlie 19 7 39
Treasure 4 24


November 2004









Berry/Vegetable Times


Strawberry Transplant
Size is Correlated With
Early Season Yield
Steven MacKenzie

During the 1997-1998 and
1998-1999 growing seasons a study
was conducted looking at yield from
individual strawberry plants. Before
transplanting the crown diameter of
each plant was recorded and then
yield data taken weekly (crown
diameter is expressed in millimeters
(mm) for reference the diameter of
a pencil is 7 mm). The data from
this study was subsequently analyzed
to see the effect that transplant size
may have on yield during each
month of the season. What was
found is that transplant size is
positively correlated with yield
during the months of December and
January. The relationship between
yield summed over these two months
and crown diameter is displayed in
the graphs below. What the graphs
show, apart from the extreme
variability in yield for plants of all


sizes, is that as crown size gets
incrementally larger yield during the
early months of the season goes up.
However, the effect of increasing
crown size appears to be reduced for
larger crowns, as the regression line
which best fits the data is not straight
but becomes more horizontal with
increasing diameter. Ultimately, the
estimated gain in yield from a 1 mm
increase in crown diameter for an
individual plant ranges from
approximately 14 g for a small
diameter plant (7 mm) to
approximately 6 g for a larger
diameter plant (15 mm). The yield
of plants less than or equal to 11
millimeters (mm) in diameter were
also compared to those greater than
11 mm. The cutoff separating these
two classes of plants is shown by the
dotted line on the graph. In this
analysis, for both cultivars tested,
Dec./Jan. yield was higher for the
larger diameter plants. For 'Sweet
Charlie' during the 1997-1998
season yield was 29% higher (206 g/
plant vs. 160 g/plant) and during the
1998-1999 season it was 24% higher


(163 g/plant vs. 131 g/plant). For
'Camarosa' yield was 17% higher
(158 g/plant vs. 135 g/plant) during
the 1998-1999 season. I recently
examined boxes of transplants and
found a significant number of plants
with crowns ranging from 8-11 mm,
which would suggest that selection
of larger plants could improve early
season yield. The effect of
transplant size was also examined for
the months of February and March.
During these months the correlation
between transplant size and yield
was not consistent.
In conclusion it appears that
using larger transplants can improve
early season yield. However, it also
appears that the gain of using bigger
transplants is diminished if
transplants are relatively large
already. Based on a visual analysis
of the graph, early season yield will
likely be compromised unless
crowns are at least 12 mm in
diameter at planting. The benefit of
using even larger diameter plants is
uncertain, but doesn't appear to be
substantial.


Figure 1. The relationship
between combinedDecember
andJanuary yzeld per plant
and crown diameter.
Each dot represents a single
plant.


'Sweet Charlie' 1997-1998

400

S300* *

200 .

Z 100 *

0
5 10 15 20
Crown Diameter (mm)


'Sweet Charlie' 1998-1999

400-

S300- _

.200 *
o,
Z 100 5
I .

5 10 15 20
Crown Diameter (mm)


'Camarosa' 1998-1999

400

S 300

S200 -

1100 r- n *

0-
5 10 15 20
Crown Diameter (mm)


November 2004








SPECIAL GCREC FACT SHEET
<

For planning purposes, it can be useful to know when diseases are likely to
occur during the season. The diagram below shows when serious strawberry
diseases have historically been a problem in west central Florida. Crown rot
refers to the plant collapse caused by Collectotrichum gloeosporioides, while
root necrosis refers to poor plant establishment and stunting caused by
Collectotrichum acutatum. Botrytis refers to Botrytis fruit rot (Gray Mold) and
anthracnose refers to anthracnose fruit rot (black spot).



Crown rots


Powdery mildew Anthracnose


Root necrosis Botrytis
S


Planting 1s Bloom 18s Harvest Gap 2nd Bloom 2" Harvest



October November December January February March




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