Group Title: Berry/vegetable times.
Title: Berry/vegetable times. April 2007.
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Title: Berry/vegetable times. April 2007.
Uniform Title: Berry/vegetable times.
Physical Description: Newspaper
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: April 2007
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Bibliographic ID: UF00087388
Volume ID: VID00049
Source Institution: University of Florida
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Berry/Vegetable

Times

April 2007


UF UNIVERSITY of
UFFLORIDA
IFAS Extension




































A University of Flonda/IFAS and Flonda Cooperative
Extension Service newsletter
Hillsborough County, 5339 CR 579, Seffner, FL 33584
(813)744-5519 SC 541-5772
Alicia Whidden Editor
Gulf Coast Research& Educaton Center
14625 County Road 672,Wimauma, FL 33598
(813) 634-0000 SC514-6890
Chnstine Cooley, Layout and Design
Craig K Chandler, Co-Editor Jack Rechcgl, Center Director
http //gcrec fas ufl edu


Cucurbit Leaf Crumple Virus- A New Virus to
Florida
Edited by Alicia Whidden
Taken from EDIS document ENY-447-
"Whitefly-Transmitted Cucurbit Leaf Crumple Virus in Florida"
S. E. Webb, F. Akad, T. Nyoike, O. E. Liburd, and J. E. Polston

Last fall the first findings of the Cucurbit leaf crumple
virus was found in north central and northeast Florida on
squash. This virus is a begomovirus and has been reported
from the western part of the US and northern Mexico.
Cucurbit leaf crumple virus infects most cucurbits-
cucumber, muskmelon, squash, pumpkin, and watermelon,
and has been reported to infect bean. The silverleafwhitefly
and the sweetpotato whitefly both transmit the virus. The
adult must feed for a minimum of 30 minutes on an infected
plant to pick up the virus and then can transmit the virus after
a delay of 6-8 hours. Once the whitefly is able to transmit the
(Continued on page 2)


Squash Silverleaf Disorder
Alicia Whidden and David J. Schuster

Just about every squash grower in Florida has had
problems with silverleaf at some time. It is caused by
Bemisia argentifolii, which is commonly called the silverleaf
whitefly for the disorder it causes in squash. Silverleaf was
first noted in Florida
around 1987. It is a
developmental disorder
caused by the feeding of
immature whiteflies and
not a disease that can be
spread from one plant to
another. Silverleaf is a
progressive silvering on
the top surface of the
leaf due to the molt in
(Continued on page 2)

1


IFAS is an Equal Employment Opportmity-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 ongin US Department of Agriculture, Cooperative Extension Service, Umversity of Flonda, IFAS, Flonda A & M
Umversity Cooperative Extension Program, and Boards of the County Commissioners Cooperating


April 2007


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Berry/Vegetable Times


(Continued from page 1 Crumple Virus Article)
virus it can infect plants for days.
Symptoms are leaves that are
thickened, distorted, curled and crumpled.
Leaves of yellow squash are rounded on the
edges. Yellow straightneck squash fruit are
streaked with green but zucchini fruit do not
show obvious symptoms.
This spring if you have any plants that
look suspicious for this virus please give me a
call so samples can be taken to determine if
this virus is present in our part of the state.
The full article can be obtained from the EDIS
website at: http://edis.ifas.ufl.edu/IN716. If
you are not able to print a copy contact me at
813-744-5519, ext. 134.


CREDITS: S. E. Webb, University of Florida


CREDITS: Chad Hutchinson, University of Florida


(Continuedfrom page. f ..- article)
separation of the epidermis of the leaf from
the lower cell layers, thus forming an air
space within the palisade cell layer. The leaf
still has the same amount of chlorophyll and
normal chloroplast development. What we are
seeing is the reflection of light by the large
airspaces in the leaf. Fruit of both yellow and
zucchini squash can be light in color to
bleached-out. Fruit quality is lower and fruit
are not marketable. Experiments have shown
size and weight of the squash do not change -
color is what is affected.
The silverleafwhitefly, Bemisia
argentifolii, was known as the B biotype of
the sweetpotato whitefly, Bemisia tabaci until
1994 when it was declared to be a new
species. Sweetpotato whitefly, B. tabaci, is
not able to cause silverleaf. Both types are
pests in warm climates of over 500 species of
plants in 74 plant families. Many vegetable
and ornamental crops that we grow in Florida
are hosts. Tomatoes, peppers, squash,
cucumber, beans, eggplant, watermelon and
cabbage are all economically impacted by
silverleafwhitefly. Other disorders caused by
silverleaf whitefly feeding are lettuce leaf
yellowing and stem blanching, pepper streak,
tomato irregular ripening, and chlorosis of
new foliage in many plants. The whitefly is a
vector of several serious plant geminiviruses
such as tomato yellow leaf curl virus, tomato
mottle virus, and bean golden mosaic virus.
Also, silverleaf whitefly vectors another plant
virus that is implicated in watermelon vine
decline. A new begomovirus called Cucurbit
leaf crumple virus also has shown up in
squash in north Florida and is vectored by
whitefly.

Overview of the whitefly lifecycle:
Whitefly females live from 10 to 24
days and can lay between about 70 and 300
eggs. The eggs are on a short stalk and hatch
in six to seven days. The first nymphal instar
is called a crawler and can move short
distances.
(Continued on page 3)


April 2007








Berry/egetable Times


(Continued from page 2)
Crawlers molt two to three days to the second
nymphal instar. The second, third and fourth
nymphal instars are immobile. The second and
third instars last two to three days each. The
latter part of the fourth nymphal instar is also
called the red-eyed nymphal or pupal stage.
Adult whiteflies will emerge in five to six days
from this stage. Adults can fly to another part
of the same plant or to another plant or field.
Whitefly adults may move several kilometers
downwind and invade new fields.


plant's defense response to the silverleaf
whitefly nymph feeding.


Credit: Phil Stansly, Immokalee REC


As stated earlier, silvering of the leaves
results from feeding by silverleaf whitefly
nymphs. Feeding by adult_silverleaf whiteflies
on a leaf does not cause leaves to turn silver. It
is only when the immature or nymphal stages
of silverleaf whitefly are feeding on the plant
that the disorder occurs, so the adult whiteflies
must be on the plant long enough to lay eggs.
Silvering occurs on newly developing leaves.
Experiments have shown that silvering
symptoms begin to show up following feeding
by the second through fourth instar. Most
likely it is caused by a component in the
digestive system or sheath saliva in the
nymphs that causes the squash leaves to
develop silvering. Also, experiments have
demonstrated that silvering can occur with as
few as 3 nymphs per leaf. It is not known if
the trigger for leaf silvering is the component
in the whitefly saliva or if silvering is the


Adult silverleaf whitefly
Controlling Silverleaf Whitefly:
Cultural controls are indispensable in
managing the silverleaf whitefly. Growers
should avoid planting squash next to crops
known to be infested with the whitefly. UV-
reflective plastic mulch repels whitefly adults
and helps plants avoid whitefly infestations
for the first few weeks until the reflectivity of
the mulch is reduced.
For chemical control, growers can use
a soil drench application of Admire Pro (and
other generic imidacloprid products),
Platinum or Venom. If foliar applications of
Venom are used, they should be made early to
avoid toxicity to bees. As nymphs appear,
growers can alternate Oberon, Knack and
Courier. The PHI for these is 7 days, which is
a problem when harvest starts. To control
whitefly adults pyrethroids, endosulfan/
Thiodan and organophosphate such as
malathion can be alternated. Combinations of
pyrethroids and either endosulfan or
malathion provide greater control than the
products alone. Products such as soaps, oils
and Prev-Am can be added to the rotation.
These products work on adults and nymphs,
but thorough coverage is essential for
maximum effectiveness. Remember to read
the label carefully for every product used.
(Continued on page 4)


April 2007








Berry/egetable Times


(Continued from page 3)
Check for a product's toxicity to bees and use
carefully. If a product is toxic to bees, use
early before flowers have formed, as bees are
crucial for a successful squash crop.




Strawberries in Brazil
Craig Chandler and Natalia Peres

In November 2006, Natalia and Renato
Lauretti and I had the pleasure of visiting
strawberry farms in the states of Parana and
Rio Grande do Sul in southern Brazil. Our
hosts for this trip were Heitor Pagnan and
Valdir Monegat, the Brazilian representatives
for Viansa strawberry nursery of Argentina.


Fig. 1 Two row beds covered with plastic tunnels.

Brazil is similar in size to the U.S., but
has only about half as many people. It is the
largest producer of strawberries in South
America. Currently in Brazil, strawberries are
produced on about 13,000 acres (5300 ha).
Production fields are located between 20 and
32 degrees south latitude (which would be
comparable, in the northern hemisphere, to the
area between Guantanamo Bay, Cuba and
Savannah, Georgia. Given this range of
latitudes, and the fact that within the growing
areas there is land suitable for strawberry


production at various elevations, up to several
thousand feet (- 1500 meters) above sea level,
Brazil can produce strawberry fruit 12 months
a year.
The areas we visited have a
subtropical climate, but as in central Florida,
temperatures can occasionally fall below 320
F (0 C) during the winter. Annual rainfall
ranges from 59 to 79 inches (150 to 200 cm),
with no distinct dry season.
The standard production system in
southern Brazil is the two-row annual
plasticulture system (Fig. 1). Clear plastic
tunnels are often used over the beds to
advance earliness of production and protect
flowers and fruit from rain and frost.
Strawberry growers traditionally
produced their own transplants, starting
originally from foundation stock they had
obtained from foreign or domestic sources.
But now it is becoming more common for
fruit growers to buy certified transplants from
licensed nurseries in Argentina and Chile.
EMBRAPA (Brazil's equivalent to the
USDA) has done some work to develop new
cultivars, but Brazilian growers are still
heavily dependent on cultivars from the
University of California, and to a lesser extent
the University of Florida.
Short day cultivars, such as Camarosa,
Oso Grande, Sweet Charlie, and Dover,
predominate in the northern or lower
elevation (i.e., warmer) growing areas,
whereas day neutral cultivars, primarily
Aromas, predominate in the southern or
higher elevation (i.e., cooler) production
areas. The short day cultivars tend to produce
higher late fall, winter, and early spring yields
than 'Aromas', but 'Aromas' will continue to
produce marketable fruit through the summer
and into the fall.
Also, 'Aromas' can be maintained in a
productive state for two years. Mature
plantings of 'Aromas' are renovated in the
spring by removing old leaves and crowns
from the plants (Fig. 1). And sometimes a


April 2007







Berry/egetable Times


small amount of a dark, soil-like material is
sprinkled around the base of each plant to aid
in new crown development.
The use of soil fumigant has been
banned in Brazil since the late 1990s, so
Brazilian strawberry growers have had to
depend on crop rotation, clean planting stock,
and good cultural practices to control soil-
borne pests and pathogens. Even without use
of soil fumigants, average yields are about
27,000 pounds per acre.
'Earlibrite' and 'Festival' (Fig. 2) are
currently being trialed in all the major
strawberry growing areas of Brazil, and are
showing promise compared to some of the
older short day cultivars.
4.


Fig. 2. 'Festival' grown in a tabletop system.


I I


Dr. Natalia Peres proudly displaying the Brazilian
flag.


Highlights on Vegetable Diagnostics
and Spring/Summer Outlook
Natalia Peres, Jim Mertely, and Clyde Fraisse

Our Diagnostic Clinic has received
very few samples in February and March.
Hopefully, that is an indication that there have
not been many problems in the field and that
the vegetable season is off to a good start. In
February, we received only 3 tomato samples;
two of them were diagnosed as TYLCV and
other was identified as late blight, caused by
Phytophthora infestans. Only two vegetable
samples were received during the entire
month of March; one identified as TYLCV
and the other as late blight. This low disease
pressure reflects the dry weather during
February and March which was not conducive
to diseases. The weather predictions for April
and early May indicate that disease problems
should remain low except perhaps for the
diseases transmitted by vectors such as
TYLCV which is transmitted by whiteflies.
The El Nifio of moderate strength last
fall failed to bring the predicted excess
rainfall and cooler temperatures to Florida this
winter. North Florida was the only area that
received near-normal rainfall whereas South
Florida only saw 50% to 75% of normal
winter precipitation. The entire state also had
winter temperatures ranging from 1 to 3 F
above normal. Water deficits in Florida range
from severe to critical and become worse as
you go south. Often following an El Nifio
winter, May and June are 10% 30% drier
than normal. However, the early summer El
Nifio effects are less consistent than those
during winter months. In addition, El Nifio
ended early this year and should not have any
effect in early summer. In the near future
(April and early May), we can expect rather
dry weather patterns, as is typical at this time
of year. Normal rainfall for April averages a
little over 2 inches in Florida. For later in the
summer (June and July), near-normal rainfall
and temperatures are forecasted. With El Nifio


April 2007









Berry/Vegetable Times


no longer affecting our climate, there is no force in the Pacific Ocean that should either
enhance nor delay the onset of the convective rainy season. Even if La Nifia were to develop
in the next couple of months, it would have little to no impact on summer climate patterns of
the Southeastern US.


March 27, 2007
U.S. Drought Monitor Mar, 27a.2007
Southeast

D ir ju r C Pev ,ir.l A re I
rrWce [. CIA [3I-M .[OM 110
Current 10.7 89.3 3011 97 0,7 0.0
LaSt Week 202 79.8 26,0 2.2 0.0 00
0r(O20=7 m")
3 MonhsAgo 52.2 47,8 10.2 15 0.0 0.0
(O/J2noo7 np)
Start of
CalendarYear 52.2 47.8 10.2 1.5 0.0 0.0
o1VIJ2oo7 nmap) ______
Startof
WaterYear 47.0 53,0 332 0.0 0.0 0.0
OneYear Ago 44.5 55,5 20.4 2.2 0.0 0.0
r&m2OOsw map)

intensity
DO Abnomlly Dry D3 Drought Extreme
01 Drought Moderate 04 Drought Excepioona
02 DrLought Sev

The Drought Monitor focuses on broad-scale conditions. USDA .
Local conditions may vary. See accompanying text summary-
for forecast statements. .. i..n.. t-_____
Released Thursday, March 29, 2007
http:l/drought.unl.edu/dm Author: Brad Rippey, U.S. Department of Agriculture




Gulf Coast REC Welcomes New
Plant Pathologist-Gary Vallad

Dr. Gary Vallad will be joining the
GCREC faculty early summer 2007 as the new
vegetable plant pathologist. Currently working '-
on diseases affecting lettuce in California, Dr.
Vallad will be leaving his position at UC Davis
to tackle diseases common to Florida vegetable
crops. With experience in both basic and
applied research, Dr. Vallad's expertise is well
suited for this research/extension appointment.
One of his research interests included
understanding the processes underlying plant-
microbe interactions and how these
interactions influence plant health. GCREC is
pleased to have Dr. Vallad become part of our
growing faculty.


April 2007








Berry/Vegetable Times


Florida Strawberry Alternatives to Methyl Bromide Chemigation Workshop
FSGA Office, 13138 Lewis Gallagher Rd, Dover, FL 33527
April 24, 2007


Moderator:


Alicia Whidden UF/IFAS Hillsborough County Cooperative
Extension Service.


PROGRAM


8:30- 9:00 am
9:00- 9:10 am

9:10- 10:00 am


10:00 10:30 am


10:30 -11:00 am

11:00 11:30 am


11:30
12:00-
1:00 -


- 12:00 pm
-1:00 pm
2:00 pm


2:00- 3:00 pm


Sign-In for CEU's, Coffee and Doughnuts
Shawn Crocker Exec. Director Florida Strawberry Growers Assoc. -
Welcome
J.W. Noling, Extension Specialist, UF, IFAS, CREC
Methyl bromide Critical Use Exemptionsfor 2007 andEPA
Reregistration of Soil Fumigants
J.W. Noling, Extension Specialist, UF, IFAS, CREC
Effect of Irrigation Volume on wetting patterns in Florida Strawberry
Soils: Implications for Soilborne Pest and Disease Control.
Mike Herrington -AMVAC Chemical Corporation
Chemigational Uses of Vapam andK-Pam
Jerry Nance Dow AgroSciences
Chemigation i/th InLine and the Science of Chemical Injection
Discussion, Question & Answer Period
Lunch
Shawn Crocker Exec. Director Florida Strawberry Growers Assoc.
Industry Updates and Information Needs
FSGA Research Farm -Field Demonstrations
1. Auto Farm and Auto Steering Demo.
2. Earthtecsolutions.com Weather and Soil Monitoring Demo.


3 Private Applicators CEU's approved


FLORIDA A4 EXPO

Mark your calendar for the next Florida Ag Expo-December 6-7, 2007
For information call Gulf Coast REC 813-634-0000 or
Florida Grower Magazine's Marc Stockwell 407-539-6552.
Visit the Expo website http://flagexpo.ifas.ufl.edu for updates.

The use of trade names in thispublication 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 directions on the manufacturer's label


April 2007




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