Group Title: Berry/vegetable times.
Title: Berry/vegetable times. January 2004.
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Title: Berry/vegetable times. January 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: January 2004
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Bibliographic ID: UF00087388
Volume ID: VID00024
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SFLORIDA Berry/Vegetable Times

EXTENSION %PV January 2004 4 e
]ntli ute ot FIrd and Agrucultural BSceWnCs 0

News from California
Spotlight on Strawberry
Problems with 'Camino Real'
'Festival' Shows Susceptibil-
ity to Leafy Growth on Fruit
Late Season Epidemics Often
Begin in January
IR-4 trials at the GCREC-
Experiments on Two Spider
Mite Predators
Pesticide Actions

Calenda of Evnt 2003-2004III

Co Exeso Office Seffiter.1 9'

Page 2
Page 2

Page 2

Page 3

2003-2004 Freeze

Adapted by Alicia Whidden from the
Center for Ocean Atmospheric
Prediction Studies

S3 El Niho and La Niha have a
Page 3
major effect on our winter weather
S patterns in Florida. El Nihio
e generally has 40% more rainfall than
normal and cooler temperatures. The
Page 5 1997-98 El Niio was one of the
strongest on record and the 2002-
Page 5 2003 was a mild one. In contrast, La
Nina brings a warm dry winter and
spring and the warm winter and
drought of 1999 and 2000 was due to
R La Niha. As well as affecting the
aF average winter temperatures both El
Niiio and La Niha suppress severe
arctic blasts of cold air that can cause
damaging freezes in Florida. Both
S effect the intrusion of cold Canadian
air into the south. El Niiio has a
strong subtropical jet that usually
m "blocks" the Arctic air masses from
S Florida. La Nifia limits the
movement of the Polar jet over the
i country which steers winter storms
rul and cold fronts to the north away

I TO-[)|

from Florida. In Neutral years
(which we are in this season) the
Polar jet position is variable and
wanders over the North American
continent. This opens up the
southern states to dramatic dips or
troughs in the jet stream that pushes
the frigid Artic air masses down from
Canada. These dips are what lead to
freezing temperatures in our area.
The last 10 out of 11 severe freezes
in the state have occurred when
conditions were neutral in the Pacific.
Since we are considered to be neutral
this year our risk of damaging freezes
is increased.

Severe Freezes of the last century
Date of Freeze ENSO Phase

Dec 1894
Feb 1899
Dec 1934
Jan 1940
Dec 1961
Jan 1977
Jan 1981
Dec 1983
Jan 1985
Dec 1989
Jan 1997

El Nihio

(Continued on page 2)

The Institute no Food and Agricultural Sciences (IFASI is an Equal Employment Opportunity Affirmative Actin Employer authorized to provide reaxarrc, educational
informatiDn and other service oDnly to individuals and irtitutions that function without regard to race, color, sex age, handicap or national origin.

A monthly newsletter of the University of Flor-
ida IFAS, Gulf Coast Research and Education
Center, and Florida Cooperative Extension
Hillsborough Co Cooperative Ext Service
5339 CR 579, Seffner, FL 33584
(813) 744-5519 SC 541-5772
Editor Alicia Whdden,
Director Mary Chernesky
Gulf Coast REC
13138 Lewis Gallagher Rd Dover, FL 33527
http //gcrec ifas ufl edu
(813)744-6630 SC 512-1160

Volume IV Issue I

Berry/Vegetable Times

Volume IV Issue 1

Weather station minimum
temperatures in the Southeast for the
last 50 years show that freezing
events are three times more likely to
occur in Neutral years. This is for
minimums of 20 or colder. Also
the odds of extended freeze events
(three or more nights at 30) in our
area is three times more likely
during a Neutral year. 100 years of
late-season freezes were looked at
and there is no connection between
type of year and the average date of
the last freeze.

News from California
Craig Chandler

A California Strawberry
Commission newsletter recently
reported that, based on a
commission survey, California
strawberry acreage for the 2004
season stands at 31,639 acres. This
is 3,409 acres or 12.1% greater than
the 2003 acreage. The Oxnard area
had the largest gain in acreage
(+1,555), giving it a total of 10,349
acres for 2004. 'Camarosa' remains
the top cultivar in California, with
9,832 acres planted (31 % of the
state's acreage), while proprietary
cultivars (from Driscolls, Cal Giant,
Plant Sciences, Inc., etc.) occupy a
total of 9,757 acres. Acreage in
'Ventana' has more than doubled
from last season to this season, with
this new cultivar now occupying
2,777 acres (or 9% of the state's
Representatives from the
Commission, the University of
California, the USDA, and the
California strawberry nursery
industry met in early December to
discuss priorities for nursery -based
research. Areas identified as high
priority by the participants include
the following: 1) determine how
pathogens are introduced and spread
in the nursery; 2) develop methods
to detect pathogens in the nursery
and in transplants before they are set
in the fruiting field; and 3) develop
control methods to prevent the

introduction and spread of
pathogens in the nursery. Meeting
participants agreed that the
Commission and nurseries should
share the cost of conducting
nursery -based research and a future
meeting will be held to work out
funding details.

Spotlight on Strawberry
Teresa Seijo and Jim Mertely

During the first three
months of the season (Oct. Dec.
2003), Colletotrichum acutatum was
the most prevalent pathogen
detected at the Strawberry
Diagnostic Clinic (20 of the 65
samples received). C. acutatum
infects all parts of the strawberry
plant. Early in the season, plants are
often stunted and fail to establish
properly. In severe cases bud rot
and death can occur. As the season
progresses, C. acutatum causes
anthracnose fruit rot. However there
is good news this season. To date
the clinic has received 38% fewer C.
acutatum infected samples than
were received during the same
period last season.
Twenty additional samples
consisted of plants collapsing from
severe crown rot. The majority of
these plants (18 samples) were
infected with Colletotrichum
gloeosporioides. Four of these
eighteen were also co-infected with
Colletotrichum fragariae. The
remaining two samples were
infected with Phytophthora sp.
Crown rot incidence in strawberry
usually decreases with cooler
weather. True to form, no samp les
of severe crown rot have been
submitted since the first week of
Charcoal rot, caused by the
fungus Macrophomina phaseolina,
has been detected at two farms this
season. M. phaseolina infects the
roots and external margins (vascular
tissue) of the crown causing

Berry/Vegetable Times
stunting, wilt and death. On one
farm the disease was associated with
beds that were not properly
fumigated. Charcoal rot is
uncommon in strawberry, but it
may become a more significant
problem if there is a fumigation
The remaining samples had
powdery mildew (4 samples),
Gnomonia leaf blight (1 sample),
angular leaf spot (2 samples), sting
nematodes (1 samples), and a
variety of abiotic problems such as
iron chlorosis or poor fertilization.

Problems with 'Camino
Real' Fruit
Alicia Whidden, Teresa Seijo. Jim

At the end of December
and early in January, problems with
'Camino Real' fruit were seen in
several fields. Both immature and
mature fruit were bronzed and
cracked, primarily under the calyx.
As the fruit ripen, the cracking can
become severe and deep under the
cap and on the shoulder of the fruit.
These symptoms were seen on a
large percentage of the fruit in the
affected fields. Samples were taken
to the Strawberry Diagnostic Clinic
and no pathogen was detected.
Another common element of all
severely affected fields was the
application of sulfur for powdery
mildew control. Dr. Kirk Larson,
plant breeder at the University of
California Davis, was contacted
and sent this information :
"Camino Real is quite sensitive to
sulfur applications, under California
conditions we find that just two
sulfur applications within a 2-week
period can cause fruit bronzing and
cracking- see Figures 1 and 2. Use
of sulfur-containing compounds
such as Captan may also be
problematic, especially if used in
conjunction or in rotation with

(Continued on page 3)

Volume IV Issue 1

sulfur. With the generally warmer
temperatures and higher irradiance
levels in Florida compared to
California, sulfur damage may be
more likely in Florida, and I would
urge growers to be very cautious
with use of sulfur or sulfur-
containing products around this
In several fields that had not
been sprayed with sulfur, some
young fruit occasionally showed
some bronzing and minute cracking.
The bronzing was not restricted to
just under the calyx and aphids were
present on the fruit. The damage
appears to be from aphid feeding.
Also some growers have found thrips
in their field recently and thrips
feeding can also cause bronzing on
fruit. There is a difference in
symptoms caused by sulfur
application (i.e., bronzing and severe
cracking usually restricted to the
stem end of the fruit) and the damage
done by the insect feeding ( bronzing
over any part of the fruit with minor
cracking, at least in immature).
Dr. John Duval has put in a
demonstration plot at the center to
try to reproduce the damage from
sulfur on 'Camino Real'. Six rates
of sulfur have been applied: control,
2.5 lbs, 5 lbs, 7.5 lbs, 10 lbs, and
12.5 lbs. It is hoped that damage will
develop even though the weather
conditions have changed.

Figures 1 and 2- 'Camino
Real' displaying

Thank you to everyone who
worked on this problem- Kenneth
Parker of Chemical Dynamics, the
faculty and staff of GCREC-Dover
and Dr. Kirk Larson of UC-Davis.

'Festival' Shows
Susceptibility to Leafy
Growth on Fruit
Craig Chandler

In early January, research
workers at the Dover center started
seeing leafy growth (Figure 1) on a
small percentage of the fruit
harvested from 'Festival' plants.
This type of fruit abnormality can be
caused by the aster yellows
phytoplasma, a bacteria -like
pathogen transmitted by leafhoppers,
but may also be non-infectious in
nature. GCREC plant pathologist
Charlie Howard, in a 1985 bulletin,
stated that in Florida this disorder is
associated with a change from low or
moderate temperature to high
temperature. Mid December of this
season could be characterized as
having low or moderate
temperatures, and late December and
early January as having relatively
high temperatures. In addition to the
fruit with leafy growth, we have
noted that some 'Festival' fruit are
more elongated or bullet shaped than
is typical for this cultivar. This
alteration in fruit shape could also be
a result of phytoplasmal infection or
weather pattern. We have seen these
types of fruit abnormalities on

Figure 1- ofphytoplasma
infection ofa 'Festival' berry.

Berry/Vegetable Times
'Festival' in previous seasons, but
they have tended to become less
common as the crop moves into the
main harvest period at the end of

Late Season Epidemics
Often Begin in January
Jim Mertely

A critical time for the
management of Florida strawberry
diseases lies just ahead. There are
two main reasons for this. Our
strawberry crop is already three
months old, and disease inoculum
can increase over time. In addition,
pathogens such as Botrytis cinerea
(Botrytis fruit rot, Figure 1) and
Colletotrichum acutatum
anthracnosee fruit rot, Figure 2) will
soon have an abundance of
susceptible flowers to infect.
Management of these two pathogens
depends on individual circumstances
and is not well suited to a "one size
fits all" recommendation. The
following comments may provide
some guidance for developing a good
disease management program.
Botrytis cinerea is usually
more predictable and easy to control.
According to research done at NC
State, nursery plants from Canada
often arrive with leaves already
infected by the fungus. These leaves
begin dying (of natural causes)
shortly after planting. As they die,
Botrytis colonizes the tissue and
produces spores which are splashed
or wind-blown to new emerging
leaves. The new leaves may appear
healthy, but as they die in January
and early February, a new crop of
spores is produced just in time to
infect second bloom flowers. The
appearance of Botrytis fruit rot on
ripening fruit is usually the result of
flower infections which occurred two
to three weeks earlier.
The key to Botrytis control
is to protect the flowers. A normal

(Continued on page 4)

Volume IV Issue 1

maintenance program of protectant
fungicides such as captain or thiram
helps to suppress this disease, and is
often sufficient when moderately
resistant varieties such as Camarosa,
Carmine, or Gaviota are grown.
However, more susceptible varieties
such as Festival and Sweet Charlie
would benefit from applications of
Elevate, Pristine, or Switch during
the second peak bloom period. One
of these products should be tank
mixed with the normal protectant
fungicide beginning at 10% bloom.
Three to four applications at weekly
intervals should adequately protect
most second bloom flowers.
Captivate can also be used during
this period as it is a pre-mix of
captain and Elevate. Additional
applications are usually not needed
since Botrytis fruit rot is naturally
suppressed as temperatures rise in

Figure 1- -I) t fruit rot.
The understanding and
management of anthracnose fruit rot
has been more difficult to achieve.
In Florida, C. acutatum is not
believed to persist on alternative
hosts or crop debris over the
summer. However, the pathogen
has been found on northern nursery
plants during each of the past three
seasons. Plant dip treatments with
Abound (Quadris), or hydrogen
peroxide (Oxidate) may reduce the
pathogen, but probably do not
eliminate it. Fortunately, not all
nursery material is contaminated, and
some fields escape the disease. If
the planting material was disease
free, measures should be taken to
protect anthracnose-free fields.
These include starting normal field

operations in these fields to avoid
spreading the pathogen by
contaminated equipment or pickers,
and regular applications of protectant
fungicides to reduce the possibility
of chance infection.

Figure 2-Anthracnose fruit rot.

Controlling anthracnose
fruit rot is much more difficult than
Botrytis fruit rot, especially if
diseased nursery stock was initially
planted in the field. The degree of
success is highly dependent on
variety and weather. Control is
rarely a problem if highly resistant
varieties (Carmine and Sweet
Charlie) are grown under normal
disease management. However, it
can be more difficult on moderately
resistant varieties (e.g., Festival or
Gaviota), and especially challenging
on susceptible varieties such as
Aromas, Camarosa or Treasure. C.
acutatum is efficiently spread by
rainstorms (splashing water) when
the weather is mild to warm. This
frequently occurs in late February or
early March when epidemics are
common. However, control
measures must be started early to
successfully avoid or delay an
epidemic. The most important of
these is maintaining regular
applications of protectant fungicides
such as captain or thiram. During the
vulnerable February to March period
(or as soon as diseased fruit are noted
in the field), additional fungicides
such as Abound, Cabrio, Pristine, or
Switch may be added to the tank
mix. Research here at GCREC-
Dover has shown that flowers are
more susceptible to infection than
leaves, petioles, or green fruit.

Berry/Vegetable Times

Diseased flowers become blighted or
develop into small black fruit which
C. acutatum uses to produce large
quantities of spores. To protect
vulnerable flowers, susceptible
varieties may benefit from
applications started before diseased
fruit appear in the field. These
applications should be made during
the second bloom when temperatures
begin to moderate and/or rain events
occur. In theory, such a program
would delay the increase in spore
numbers which eventually results in
epidemics on ripening fruit.
While fungicides are an
effective tool for the control of
anthracnose and Botrytis fruit rots,
good cultural practices should not be
ignored. The fertilization program,
for example, influences the
development of both diseases.
Excessive fertility produces large
plants whose rank foliage covers
flowers and fruit, delays drying, and
promotes infection by B. cinerea. In
addition, spray coverage is less
complete when the canopy becomes
overly dense. Excessive fertilization
also promotes the development of
young tender tissues (e.g., petioles)
which are more susceptible to
infection by C. acutatum. Plant
sanitation is also an important
cultural control method. Harvesters
should be encouraged to pick and
throw down diseased and other cull
fruit. In addition, harvest intervals
should be short enough to avoid the
appearance of over-ripe fruit in the
field. Wise management practices
such as these will reduce dependence
on fungicides and some of the
control failures that inevitably occur.

IR-4 Trials at the GCREC-
John R. Duval

Currently two herbicides,
sulfentrazone and terbacil, are being
tested on an IR-4 residue study fro
strawberry. Sulfentrazone is an

Volume IV Issue 1

under mulch pre -emergence,
currently without a label, and
terbacil is currently labeled but has a
110-day PHI postharvest interval.
The purpose of these trials is to get
PHI's down to below 50 days. Since
field preparation may take place
several weeks before planting and it
is unusual to produce berries 40 days
after transplanting, a PHI of 50 days
should be sufficient to avoid
interference with the first harvest of
the season. Thanks to the efforts of
Dr. Bill Stall and Berry Tanner
from Gainesville, we should have
new tools to manage weed pests in
strawberry in the coming years.

Experiments on Two
Spider Mite Predators
Jim Price

In the recent November
issue of Berry/Vegetable Times,
Liburd, Seferina and Dinkins
discussed thatNeoseiulus
californicus predatory mite
performed well in controlling
twospotted spider mites in North
Florida where they had observed
poor results with Phytoseiulus
persimilis predatory mite. Since that
report, several scientists within the
University of Florida and Clemson
University have begun cooperative
work to determine if there is an
advantage of N. californicus over P.
persimilis in areas of the
southeastern US.
Accordingly, field
experiments have been established in
Charleston, South Carolina (1), north
Florida (1) and west-central Florida
(3) strawberry production areas.
Three treatments in each experiment
include large areas where spider
mites are managed using N.
californicus, P. persimilis and a
chemical control check. Data will be
collected through the spring 2004
crop and will be examined
collectively and by locality.
It is understood that the two
species of predators posses different

optimal environmental humidity and
temperature for foraging, responses
to insecticides used in strawberry
culture, and food host ranges and
consumption rates. For instance, N.
californicus tolerates Brigade
bifenazate insecticide well and can
survive on pollen or some mite prey
other than spider mites if the
preferred spider mite prey is
unavailable. P. persimilis tends to
consume more spider mites each day
than can N californicus. Neither
predator species can damage
strawberry crops.
The results of these
experiments can be useful to
determine the better predator for the
prevailing strawberry environmental
conditions in the southeastern US.
Outcomes at the various sites will be
reported in this newsletter.

Valent Co. announced that Zeal
(etoxazole) ovicidial miticide is now
approved for Florida strawberry.
Restricted to one application per season.
Trials on this product performed very
well at GCREC.

Pesticide Registrations
and Actions
Chemically Speaking, 12/03

* The Florida Department of
Agriculture and Consumer
Service (FDACS) issued the
Special Local Needs [24(c)]
registration number FL-030013
to Nichino America for use of
Courier (buprofezin)
insecticide to control whiteflies
on tomato with a one-day pre-
harvest interval. EPA
registration number 71711-15.
(FDACS letter of 10/28/03).
* On October 3, FDACS
registered the fungicide
EnduraR (boscalid) for control
of diseases on lettuce, potato,
cucurbits, fruiting vegetables,
and other crops. EPA

Berry/Vegetable Times
registration number 7969-197.
(FDACS PREC November
* On October 3, FDACS
registered the fungicide Tanos
(famoxadome) for control of
diseases on cucurbits, potato,
tomato, and other crops. EPA
registration number 352-604.
(FDACS PREC November
* On October 3, FDACS
registered the fungicide
Pristine (boscalid) for control
of diseases on carrot, strawberry,
bulb vegetables, and other crops.
EPA registration number 7969-
199. (FDACS PREC November
* On November 6, the FDACS
registered the herbicide
EnvokeR (trifloxysulfuron-
sodium) for selective control of
certain broadleaf, sedge, and
grass weeds in cotton,
sugarcane, and transplanted
tomato. EPA registration
number 100-1132. (FDACS
PREC December Agenda).
* Bayer CropScience announced
in Nov. that due to incidences of
injury to blueberries after
applying Rovral (iprodione)
fungicide in Georgia in 2003,
the company is prohibiting the
use of all RovralR products on
all varieties of blueberries in the
United States. The RovralR
product manager can be reached
at 888-992-2937. (Bayer
CropScience letter of 11/10/03).
* The pesticide community now
has a tool to locate product
collection and disposal
opportunities. Earth 911, www. asp, offers
information on approximately
375,000 communities, which
users can access by entering a
zip code. (Pesticide & Toxic
Chemical News).

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