Group Title: Berry/vegetable times.
Title: Berry/vegetable times. September 2007.
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Title: Berry/vegetable times. September 2007.
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: September 2007
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September 2007


UFFl6 RIDA IFAS EXTENSION Berry/egetable Times


From Your Agent:
Looks like it will be a La Nina Winter!


(
2FLOICDA Ar EXvO
December 6 and 7, 2007 at
Gulf Coast Research and
Education Center- Balm
http://flagexpo.ifas.ufl.edu.
A University of Floda/IFAS and Florida
Cooperative Extension Service newsletter
Hillsborough County, 5339 CR 579
Seffner FL 33584
(813)744-5519 SC 541-5772
Joe Pergola, County Extension Director
Alicia Whidden, Editor
Gulf Coast Research & Education Center
14625 County Road 672,Wimauma, FL 33598
(813)634-0000 SC514-6890
Christine Cooley, Layout and Design
Craig K Chandler, Co-Editor
Jack Rechcigl, GCREC Center Director
http //gcrec ifas ufl edu


The Southeast Climate Consortium has announced a
La Nifia watch which means that conditions are right for the
development of a La Nifia event and this development will be
watched to see if it continues for the next one to three months.
For those that attended this year's Agritech you heard Clyde
Fraisse from UF say that there was a 60% chance of this
winter being a La Nifia event and 40% chance of it being a
Neutral year. Events in the Pacific Ocean are continuing to
look like it will be a La Nifia which will go through the fall
and winter.
For the past few months there have been lower than
average water temperatures near the coast of South America
and the colder water has been deeper than usual and this is the
time of year La Nifia usually forms. La Nifia is when the sea
surface temperatures along the equator in the eastern and
central parts of the Pacific Ocean are several degrees lower
than average and it lasts for at least five months. La Nifia
occurs every two to seven years.
(Continued on page 3)


Greetings from the GCREC!
Gary Vallad, GCREC, Assistant Professor Plant Pathology

I'm grateful for this
opportunity to introduce myself
and tell you a bit about my
research background. I did my
undergraduate and initial
graduate studies at North Dakota -
State University, where I
received my Master's in Crop
and Weed Science studying the
genetics of dry edible beans, Phaseolus vulgaris. I then
migrated from plant genetics to plant pathology at the
(Continued on page 2)


1
IFAS is an Equal Employment Opportunty-Affirmative Action Employer authorized to provide research, educational information and other services onlyto individuals andinstitutions that
function without regard to race, color, sex, age, handicap, or national origin US Department of Agriculture, Cooperative Extension Service, Umversity of Flonda, IFAS, Flonda A & M
University Cooperative Extension Program, and Boards of the County Commissioners Cooperating


Berry/Vegetable

Times

September 2007








Berry/egetable Times


(Continuedfrom page 1)
University of Wisconsin, Madison.
For my Ph.D. in Plant Pathology I was
part of an interdisciplinary team of scientists
investigating the use of bio-solids generated
from local paper-mills as a soil amendment,
and the impact of these amended soils on the
health of potato, snap bean and cucumber
grown in a 3-year rotation. The soils amended
with bio-solids had a dramatic impact on
diseases caused by soilborne pathogens,
especially those caused by species of Pythium.
More interesting, several foliar diseases were
also suppressed, but only in field plots
amended with composted bio-solids. I
demonstrated that this foliar disease
suppression was independent of plant fertility,
but due to a phenomenon called induced
resistance where plants exhibit an elevated
defense response against pathogen attacks.
My post-doctoral studies at the
University of California, Davis, focused on
Verticillium wilt of lettuce caused by the
soilborne fungus Verticillium dahliae. I
worked closely with a lettuce breeding
program to identify sources of resistance and
to develop and release resistant varieties. I
also studied the process by which the fungus
colonizes the plant and developed cultural
practices to lessen the economic impact of
Verticillium wilt on lettuce production. I also
initiated population studies to determine the
origin of lettuce-infecting isolates and the
potential role of infested seed in distributing
these isolates.
My responsibilities at the GCREC are
to support the vegetable and ornamental
industries of Florida through research and
extension. My research will focus on the
diagnosis, remediation and management of
vegetable and ornamental diseases using
traditional and contemporary methods to
understand plant-pathogen interactions, limit
the impact of disease and improve crop
production; with an emphasis on the
development of economically sustainable


control strategies. Current research efforts are
focused on cultural practices to improve the
efficacy of several methyl bromide
alternatives, and the integrated management
of tomato yellow leaf curl. Extension efforts
will cater to the needs of local grower,
industry, and public interests. I look forward
to meeting everyone in the vegetable industry
and county extension, especially with the start
of a new growing season.
On a more personal level, growing up in rural
North Dakota, I'm a natural outdoorsman who
enjoys camping, fishing, hunting, and a good
game of golf. However, I'm actually a native
Floridian from Homestead, Florida. Half of
my family tree still resides within the state,
which was a great perk to return. With me I
brought my wife of 14 years, Susana, my 12
year-old son, Lukas, and 2 year-old daughter,
Alyssa. I know we are all excited about our
new life in Florida, and the long awaited
opportunities it presents... especially enjoying
winter on the beach.
Again, I'm excited to be here and look
forward to working with everyone in the
vegetable industry to meet current and future
challenges. GO GATORS!




Interesting FACT-
If you watch the hit TV
show Numbers" you
know mathematical
formulas can be used to
help solve crimes. A
mathematical formula
can also be used to
describe how seeds on a
strawberry spiral and the
curve of a nautilus shell. The formula is the
Fibonacci sequence. This is where each
successive number is the sum of the previous
two numbers:
(0,1,1,2,3,5,8,13,21,34,55,89,144...)


September 2007








Berry/egetable Times


(Continuedfrom page 1)
What La Nifia means for us is that from
October to March the weather will be warmer
and drier for Florida, central and lower
Alabama and central and south Georgia. La
Nifia weather can be good in some situations
and bad in others. The dry weather is good for
a decrease in strawberry fungal and bacterial
diseases and might let you cut back on the
number of fungicide sprays you need to apply
but spider mites love warm dry weather so be
sure to scout for signs of infestation. We may
be facing severe water shortages in the spring
and with dry warm weather it may be hard to
keep spring crops watered well. Also if you
have livestock on pasture or produce hay this
will not be a good weather cycle for you. The
Southeast Climate Consortium looked at past
La Nifia events and estimated the impacts if we
have one this year. For central Florida in
January 2008 the chance of having normal or
above average rainfall is only 8%. The chance
for it to be moderately dry which means
rainfall amounts are slightly below normal to
half the normal amount is 20%. Unfortunately
the chance for conditions to be very dry is a
whopping 72%.
Check out the Southeast Climate
Consortium website at www.AgClimate.org
for more information. Remember to think
about the weather as you plan for your winter
and spring crops!

A4licia Whlidden
Hillsborough County Extension Service


New Herbicide Labels in
Vegetables
William Stall, UF/IFAS Horticultural Sciences
Vegetarian Newsletter, 09/07

Rely (glufosinate) labeled in Potato Vine
Desiccation. Rely herbicide has received
labeling in Florida for the desiccation of
potato vines before harvest. Apply Rely
herbicide at the beginning of natural
senescence of potato vines at 3 pints per
acre (0.375 lb ai). Apply only one
application per harvest. Thorough coverage
of the potate vines to be desiccated is
essential. Do not harvest potatoes until 9 or
more days after application.

Prowl H20 (pendimethalin)
Supplemental Labeling for use on
Tomato and Pepper.
Prowl H20 may be applied to tomatoes and
peppers (including bell pepper, chili pepper,
cooking pepper, pimento, sweet pepper).
Prowl H20 may be applied as a post-
directed application to transplanted or
established direct-seeded tomatoes and
peppers at 1.0 to 1.5 pints per acre (0.475 to
0.7125 lb ai). Rainfall or irrigation is
needed to activate the herbicide. If this does
not occur, mechanical incorporation is
needed. Prowl H20 is labeled for a
broadcast pre transplant surface application
also, but not to rows to be covered with
plastic. Do not apply within 70 days of
harvest.
Prowl H20 Supplemental Labeling for
use on Strawberry. Prowl H20 may be
applied at 1.5 to 3.0 pints per acre (0.7125
to 1.42 lb ai) at pre transplant time. Do not
apply to the bed or row if plastic mulch is
applied. Adequate rainfall or irrigation after
application is needed prior to weed
emergence for most effective weed control.
Do not apply within 35 days of harvest.
Labeling for these herbicide uses must be
in the possession of the user at the time of
pesticide application.


The use of trade names in this publication is
solely for the purpose ofproviding specific
information. It is not a guarantee or warranty of
the products names and does not signify that they
are approved to the exclusion of others of suitable
composition. Use pesticides safely. Read and
follow in, L i. 'ii on the manufacturer's label.


September 2007







Berry/egetable Times


Some Interpretations of Intrepid
and Sevin Strawberry Labels
James F. Price and Curtis Nagle, GCREC

Pesticide labels communicate the
lawful use of pesticides and applicators must
comply with label provisions. Sometimes,
though, the meanings of the label statements
are subject to interpretation that can expand or
restrict usage. This article discusses the
interpretation of provisions stated on Sevin
(carbaryl) and Intrepid' (methoxyfenozide)
labels.
Intrepid' has been available for over a
year to control armyworms and other worms
on strawberries. Its label for strawberries
states the product should be used, "For early
season applications only to young crops and
small plants." Responsible folks at Dow
Agrosciences (provider of Intrepid') declare
that this does not limit the use of Intrepid to
early season, but that it can be used at any time
during the season.
This is good news for growers who
wish to have an additional mode of action
available for season-long armyworm control.
Intrepid is applied at 6 to 12 fluid ounces per
acre per application and a maximum of 64
fluid ounces per acre per season.
Sevin is available to control some
beetles, worms, and tarnished plant bug in the
pre-fruiting period (it has an unfortunate 7-day
pre-harvest interval (PHI)). The Sevin label
states, "Do not plant rotational food or feed
crops not listed on this or other carbaryl labels
in carbaryl treated soil." There seems to be no
end to the prohibited planting period.
Responsible folks at Bayer Cropscience LP
and at Drexel (providers of Sevin) relate that
the restriction is for 1 year following
application. Additionally, the restriction is
relevant regardless if Sevin were to be applied
to the soil or to the plant. Acceptable
rotational food crops important in the Plant
City area include tomato, pepper, eggplant,


melons, squash, cucumber, bean, southern
pea, okra, and others, but do not include
onion.
Understanding the limitations of
these labels results in more effective, safer,
and compliant pest management.



The Concept of Yield Dispersion
and Compression Due to
Temperature
Steven MacKenzie and Craig Chandler

Over the last couple years we have
been conducting studies to find better ways
to predict fruit yield. Predicting yield in
advance will always be a challenge to both
growers and shippers. The primary reason
why it is difficult to predict yield prior to a
harvest interval is because the fruit
development time (the time from flowering
to harvest) for strawberry is dependent on
temperature and temperature fluctuates
throughout the season. If temperature
remained constant throughout the season one
could simply count the flowers opening over
a predefined interval before a harvest and
obtain a consistent estimate of yield. This
scenario is illustrated in figure 1, case A. In
this scenario there is a hypothetical cultivar
in which the time from flowering to harvest
is exactly 4 weeks at 63.50F. If the
temperature were to remain at exactly 63.5F
over the time fruit developed, flowers from
the one week flowering interval depicted in
figure 1 would all ripen during week five.
Unfortunately, average temperature
fluctuates from week to week resulting in
phenomena that we have termed yield
dispersion and yield compression. The
concept of yield dispersion and compression
is illustrated by two scenarios depicted in
figure 1 in which temperature suddenly drops
(Continued on page 5)


September 2007








Berry/Vegetable Times


(Continued from page 4)
or rises during the harvest week. In scenario B,
temperature is at 63.50F from the beginning of
flowering to the end of week four when fruit
would just begin to ripen. During the 5th week
temperature suddenly drops to 590F and remains
there. Fruit development times lengthen when
temperature declines. For fruit just about to ripen
(those which flowered on the Saturday of the
flowering interval), temperature wouldn't effect
the fruit development time that much because the
fruit were almost fully developed. However, for
fruit from flowers that opened later during the
flowering interval the fruit development time
would get substantially longer. The result of this
is that only flowers from Saturday to Thursday of
the flowering interval would ripen during the
harvest week and yield would decline from that
observed in scenario A. In scenario C, it is
assumed that temperature remained constant over
the first four weeks and suddenly rose to 680F
during the course of the harvest week and
remained there. Because the temperature
increased, fruit development times would
shorten. They would also shorten to a greater
extent for fruit from flowers opening later
because the increase in temperature would have
begun when these fruit were younger. The result
is that not only would fruit from flowers open


during the initial one week flowering interval
ripen during the harvest interval, but fruit from
flowers after this interval would ripen too.
Ultimately, the yield observed during the
harvest week in scenario C would be greater
than that observed in scenario A. Scenario B,
where temperature declined from the time
flowers opened to when they produced fruit, is
consistent with temperature behavior at the
beginning of the season and helps explain why
yields are typically more dispersed early on.
Scenario C, where temperature increased from
the time flowers opened to when they produced
fruit, is more consistent with temperature
behavior late in the season and helps explain
why yields are more compressed toward the end
of the season. An unfortunate byproduct of
yield compression is that the increase in yield
observed over a harvest interval comes at the
expense of yields at other times. Temperatures
typically fluctuate around historical averages
and abnormal highs give way to abnormal lows
which lengthen development times and produce
yield shortfalls.
We have developed a yield prediction
model for 'Strawberry Festival' that uses flower
count data as an input. The model incorporates
typical dispersion and compression trends
(Continued on page 6)


Flowering interval Harvest
Weekly Week5
5 Su M T W Th F Week2 Week3 Week4 S Su M T W Th F
SI I

63.5 'F 63.5 F


I I
63.5 F 59 *F


63.5 F 68"F


Figure 1. Narrow bars below the main bar represent the time between flowering and fruit ripening. Black
bars are for fruit developing under scenario A, where temperature remains at 63.50F throughout the 5 week period.
Blue and green bars are for fruit developing under scenario B, where temperature is 63.50F for 4 weeks and then
declines to 590F during the harvest week. Red and orange bars are for fruit developing under scenario C, where
temperature is 63.50F for 4 weeks and then increases to 680F during the harvest week. The green bar depicts the
development of a flower open during week 1 that produced a ripe fruit after the harvest interval (week 5) and the
orange bars represent flowers open after the flower interval that produced ripe fruit during the harvest interval.


September 2007








September 2007


observed over the course of the season to come up
with a forecast. The yield forecast can also be
adjusted to accommodate abnormal expected
temperatures when temperature forecasts become
available leading into harvest weeks. Predicting
yield is not as simple as predicting the number of
fruit expected to ripen. Yield is also dependent on
the size of fruit. Bigger fruit add weight and when
fruit are large they are less likely to be culled. A
method to predict fruit weight and the proportion of
fruit culled is also included in the model; however
estimating these variables reduces lead time and
adds to model complexity. For this reason a model
that doesn't rely on fruit size determination is also
going to be available. If any individual would like
to try the models they will be available soon in an
excel spread sheet. To request the model equations
and instructions on how to use them email your
request to Steven MacKenzie (sjmac@ufl.edu).



New Tomato Breeder on Board at
GCREC

Dr. Jeremy Edwards is just one of the
newest additions to the GCREC faculty. A
former employee of UF/GCREC, Dr. Edwards
will be developing a new tomato breeding
program that will compliment the current
program directed by
Dr. Jay Scott. After
receiving his Ph.D.
from Cornell
University in plant
breeding and
genetics, Dr. Edwards
worked as a
postdoctoral
researcher at the
University of
Arizona. He is committed to applied research
aimed at cultivar development using state of
the art techniques. Watch for more from this
new breeder in future BVT issues.


Berry/Vegetable Times




FLORIDA A EXpO

Session Preview
Thursday Morning
December 6, 2007


Moderator: Alicia Whidden, Hillsborough
County Extension Service, Seffner
8:50 am Welcome Dr. Jack Rechcigl,
Director, UF/IFAS, 6CREC, Balm
Dr. Jimmy Cheek, Vice President, UF/
IFAS, Gainesville
9:00 am Increasing Efficiency with Harvest
Aid Equipment for Vegetables
Dr. Steve Sargent, UF/IFAS,
Horticultural Sciences Dept.,
6ainesville
9:20 am Cucurbit Insects and Related
Viruses Dr. Susan Webb, UF/IFAS,
Entomology & Nematology Dept.,
Gainesville
9:50 am Using GIS Technology to Study
Changes in Whitefly Density and
TYLCV Incidence in Tomato?
Dr. Dave Schuster, UF/IFAS, 6CREC,
Balm
10:10 am Break and Visit Vendors

Alternative Crops for Florida Growers
10:40 am The Three P's: Peaches, Plums
and Persimmons Dr. Jeff Williamson,
UF/IFAS, Horticultural Sciences
Dept., Gainesville
11:10 am Raspberry A Potential New Crop
for Central Florida Dr. Craig Chandler,
UF/IFAS, 6CREC, Balm
Dr. Adam Dale, Univ. of Guelph,
Simcoe, Ontario
11:25 am Development of Ethanol Production
in Florida Dr. Bradley Krohn, President
& CTO, US EnviroFuels
11:50 Lunch and Visit Vendors








Berry/Vegetable Times


Special GCREC Fact Sheet
Charcoal Rot of Strawberries Caused by Macrophomina phaseolina
Natalia A. Peres and J.C. Mertely

Introduction
Charcoal rot, caused by Macrophomina phaseolina, is a relatively new disease in Florida. This
disease was first observed in December 2001, when collapsed and dying strawberry plants from a com-
mercial field were submitted to our Diagnostic Clinic. During the 2003-2004 season, M phaseolina was
isolated from dying strawberry plants taken from the original field and two additional farms. Since then,
a few additional samples have been received in our Diagnostic Clinic every season. Affected plants are
often found along field margins or other areas inadequately fumigated with methyl bromide. Charcoal
rot has also been reported on strawberry in France, India, and Illinois.

Causal Agent and Symptoms
Symptoms caused by Macrophomina phaseolina are similar to those caused by other crown-rot
pathogens such as Colletotrichum and Phytophthora species. Plants initially show signs of water stress
and subsequently collapse (Fig. 1). The cut crowns of affected plants reveal reddish-brown necrotic areas
on the margins and along the woody vascular ring (Fig.2). To confirm a diagnosis, a sample must be
submitted to a Diagnostic Clinic and the pathogen must be isolated from the diseased crowns and identi-
fied.

Disease Development and Spread
Very little is known regarding this disease on strawberries. M phaseolina is a common soil-
borne pathogen in many warm areas of the world and has a very broad host range. Many vegetable crops
planted as second-crops after strawberry such as squash, cantaloupe, and peppers, among others, are sus-
ceptible. In addition, legumes planted as summer crops are also susceptible. Those infections may in-
crease inoculum levels of M phaseolina in the soil. In general, high temperatures and low soil moisture
favor infection and disease development.

Control
No fungicides are labeled for control of charcoal rot on strawberries. Topsin 'A' is labeled for
control of charcoal rot on other crops. Our preliminary results with Topsin I' have shown that applica-
tion of this product may help delay onset of symptoms. Studies are currently being conducted to deter-
mine if cultivars differ in susceptibility to charcoal rot. This disease may be an emerging threat as the
Florida strawberry industry transitions from methyl bromide to other fumigants.

















Fig. 1. Plant wilting symptom of charcoal rot. Fig.2. Internal crown symptoms of charcoal rot.


September 2007




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