Group Title: Berry/vegetable times.
Title: Berry/vegetable times. December 2003.
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Title: Berry/vegetable times. December 2003.
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: December 2003
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Bibliographic ID: UF00087388
Volume ID: VID00023
Source Institution: University of Florida
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9. FLORIDA Berry/Vegetable Times

EXTENSION Pg December 2003
]nticute oi Frwd and AgrcultuTal Scenrc Vs 0

In this issue...
Petiole Sap Testing Page 2
Use This Method To Check Page 2
The Vigor ofPredator Mites
As Soon As They Arrive
Ideas for increasing Florida Page 2
strawberry growers 'profit.
Pesticide Regulations and Page 3
1 i1 Page 4

Happy Holidays Page 5

Caena ofEens20320

Jan 12 Petcd TsigHisoug
Cont Exeso fice Sefnr a.
Fe 232IAG 04 ot ne

From Your Agent...
Here are some updated
phone numbers to put on Central
Posting at your farm locations. The
National Poison Control number is 1-
800-222-1222. The National
Pesticide Information Center, which
can give information on pesticide
toxicity and symptoms, is 1-800-858-
7378. Both of these are very
important numbers to keep handy in
case of emergency. Be sure and
remember to have all required
information on your central posting
location. You must include:
approved EPA safety poster,
information on the nearest emergency
medical center- name, phone number
and address, and what pesticides have
been sprayed on the field. Spray
information will include location of
where the pesticide was sprayed in
the field, product name, EPA
registration number of product, active
ingredient, the time and date you
sprayed, the re-entry interval in hours
and then the date and time re -entry is

Ya/ppy Yo/iddays!
Alicia Whidden

Update on Blueberry
Summer Leaf Spot
Disease Control
Alicia Whidden

The Fall Blueberry Short
Course, sponsored by the Florida
Blueberry Growers Association, was
held Nov. 6, 2003 in Gainesville and
had an excellent program. A talk was
presented by Dr. Jeff Williamson on
the fungicide trial conducted this
summer to look at fungicides and
their control of summer foliar
diseases and the current status of
Indar@ which has a Section 18
through Sept. 14, 2004. The health
of the leaves this year is very
important for next year's fruit crop.
The main foliar diseases in
blueberries are Septoria, Rust and
Phyllosticta leaf spot. Phyllosticta
leaf spot is the main fungal leaf
disease for the southern part of the
state. Cabrio@ did the best job of
control in this year. Abound@ also
did a good job of controlling disease
but was statistically ranked second
with Indar@ not doing as good a job
as the other two. When using
Cabrio@ or Abound@, which are
strobilurins, you are limited by the
label on the total number of
applications you can apply and also
you are to apply no more than 2
consecutive applications before you
rotate to another product with a
different chemistry. You can rotate
with Indar, Alliete or Captan which
are labeled for blueberries and have a
different chemistry from each other.

11w Institute t itFood anrd Agricultural 5k6"res (II 1'0 1 h i I t1 Trnp I- wmrt OppTrtunily Atffrmative Actio Emrployr inuthorizrL tw provider &rch, euductinona
intonatioun and other servioes only to individuals and institutions that function without Tegalrd to race, color, wN, 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 Whidden,
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 III Issue 12

Berry/Vegetable Times

Volume III Issue 12

Just remember it is important to
keep healthy leaves on the bushes
into fall to harvest a good crop next

Petiole Sap Testing
John R. Duval

Monitoring the nutritional
status, over the course of the season,
of strawberry plants is critical for
optimizing yields. Deficiencies in
the early season can decrease yields
later in the year. Analysis of plant
tissue is the best way to determine
how well a fertilization program is
meeting the demands of strawberry
growth. There are means to
determine the plants nitrogen
(nitrate) (N) and potassium (K)
levels directly in the field. The use
of hand held ion specific electrodes
(Cardy meters) provide a simple and
effective way of doing this in the
field. Ten to 15 petioles are
removed randomly from actively
growing plants then pressed to
remove sap from the petioles. This
sap is then placed on the electrode
and a value in parts per million is
given for the specific ion. This
information can be used to increase
or decrease the fertilization. The
sufficiency range of values for N
(nitrate) and K are given below.
These numbers are a guide.
Weather conditions may decrease (if
temperatures are cool) or increase (if
temperatures are warm) desirable N
and K values during December,
January, and February.

Month Petiole sap concentration

N (nitrate) K
Nov 800-900 3000-3500
Dec 600-800 3000-3500
Jan 600-800 2500-3000
Feb 300-500 2000-2500
Mar 200-500 1800-2500
Apr 200-500 1500-2000

Use This Method To
Check The Vigor of
Predator Mites As Soon
As They Arrive
Jim Price

Life is difficult during
those first few days after predator
mites are released into strawberry
fields for spider mite control. At that
point, the predators already have
been washed from cozy plant homes
only a leg's reach from food,
dumped into bottles of vermiculite,
chilled, jostled in the belly of an
airliner and on the floor of a
delivery van and finally sprinkled
into our fields.
Then their work starts. The
predators quickly must acclimatize
themselves to our fields and for the
first time in their lives actually
search for food. There may be more
than ten plants, each with perhaps
21 leaflets between the predator and
her first meal in Florida. And that
meal must be found and eaten before
her fuel, taken on in California,
Holland, or other distant place, runs
out. To survive this and lay eggs to
start a family in our fields, predators
must be in good vigor at the time of

A predator's vigor can be
related to the health of her parents'
colony back home, the time and
temperature in transit, the amount of
moisture in the vermiculite and
other factors. No one can determine
with certainty just how well a
shipment of predators will perform,
but shippers often instruct buyers to
stand bottles of predators on end to
confirm that the predators are alive

Berry/Vegetable Times
by observing them walking around
the bottle neck.
We have developed the
"coffee mug method" to help
growers make additional inferences
about the vigor of predators
commonly shipped at about 2,000
predators in a pint bottle. The
method to employ this technique is
described below.
Immediately after the
shipment arrives, randomly select
bottles of predators to be tested.
Five or six bottles of a small
shipment, or at least one bottle from
each shipping container of a large
shipment should be checked. Rotate
each bottle end over end and along
its axis for 15 seconds to distribute
the predators evenly within the
vermiculite. Pour a bottle capful
(about 10 ml) into a white coffee
mug warmed to room temperature.
A Styrofoam coffee cup is not
suitable. Wait 10 minutes and
immediately count the predators that
have climbed to the top of the mug.
If ten or more have reached
the top in 10 minutes, the bottle
contents have arrived in good
condition. If none or very few reach
the top in 10 minutes, remix the
contents and take another sample. If
the second results are consistent
with the first, then the contents
likely will not be effective. In any
case, draw inferences concerning the
entire shipment based on results of
tests on several bottles. Claims
against suppliers or shippers should
be supported also by the whole
bottle test described on the
Do not unnecessarily delay
releasing the predators into the field.
Their vigor declines each day the
predators remain in post-shipment
cool storage.
Finding spider mite food
and laying first eggs are big tasks
for predators in strawberry fields
and only those in good vigor are
likely to get the job done. This
method removes some of the
uncertainty about whether a
shipment can accomplish this and

Volume III Issue 12

helps a successful strawberry season
get off to a good start.

Ideas for increasing
Florida strawberry
growers' profit. Part II
Craig Chandler

In part one of this article, which
appeared in last month's issue of
Berry/Vegetable Times, the focus
was on production costs. This
month, I present some thoughts on
supply and demand.
Increasing fruit yield per
acre can increase profits. Higher
yields allow growers the option of
either selling more fruit or reducing
their acreage and harvesting the same
amount of fruit as they did before the
yield increase. We may, however, be
reaching the limits for yield in
strawberry. The average seasonal
yield for Florida strawberries is
currently about 25,000 lbs/acre,
which is substantially higher than for
other fresh fruit crops grown in the
southeastern U.S. For example, the
average yield for high-density
blueberries in Florida is only about
6,000 lbs/acre, and the average yield
for peaches in Georgia is about 8,000
lbs/acre (www.usda. gov/nass).
Also, the wisdom of developing
cultivars with greater total yield per
plant may be questionable, because
high yield can result in low soluble
solids (an important component of
flavor). In fact, the pineapple
breeder in Queensland, Australia,
Garth Sanewski, is breeding for
lower yield per plant, resulting in
sweeter and better-flavored fruit.
Even if higher total yield is
not possible or advisable, it is
possible (and highly desirable) to
increase marketable yield. For
example, marketable yield can be
increased by eliminating or reducing
losses due to diseases, arthropod
damage, fruit malformation, and
cracking. Certainly great strides
have been made in the areas of

disease and pest control, and I have
no doubt that additional progress will
be made in the future. As for fruit
malformation and cracking, breeders
are working diligently to develop
cultivars that produce symmetrically
shaped and crack-resistant fruit over
a range of environmental conditions.
The timing and consistency
of yield is also amenable to
manipulation. Increased yields
during a desirable market window
can result in increased profit for the
grower. For information on how to
modify the timing and consistency of
strawberry yield, please see
"Smoothing out the peaks and
valleys in winter strawberry
production" in the Sept. 2002 issue
of Berry Times (http://strawberry.
Another way for growers to
increase their profits is to obtain
higher overall prices for their fruit.
This requires increased demand for
the fruit. From the research side, I
think we can create a greater demand
for strawberries by developing
cultivars and cultural practices that
result in more desirable fruit. Traits
that would make the fruit more
desirable include uniform shape and
color, better flavor, and greater
health benefits.
In conclusion, I believe
research and development efforts can
help lower production costs, increase
marketable yield, and create fruit that
is in high demand by consumers.

Pesticide Regulations and
Chemically Speaking

On September 5, the FDACS
registered the insecticide
Proclainm (emamectin
benzoate) for control of certain
lepidopterous larvae on fruiting
vegetables, including brassica
and turnip greens. The EPA
registration number for the
Syngenta Crop Protection

Berry/Vegetable Times
product is 100-904. (FDACS
PREC, October Agenda)
* On September 25, FDACS sent
a letter to Florida Fruit and
Vegetable Association to inform
them that the EPA had granted a
specific exemption for the use of
Indart (fenbuconazole)
fungicide (EPA Reg. #62719-
421 or 707-239) for control of
leaf spot and rust on bearing
blueberry. The exemption
expires on September 14, 2004.
(FDACS letter of 9/25/03)
* The time limited tolerance for
vinclozolin (Ronilan) on snap
bean has been extended until
September 30, 2005, which is
also the last date of legal use of
this fungicide on this crop.
(Federal Register, 9/30/03)
* Based on a request from
Syngenta Crop Protection,
tolerances have been obtained
for the herbicide trifloxysulfuron
in citrus (0.03 ppm), cotton
undelinted seed/gin byproduct
(0.05/1.0 ppm), sugarcane (0.01
ppm), and tomato (0.01 ppm).
(Federal Register, 9/17/03)
* Based on a request from Valent
U.S.A. Corporation, tolerances
have been obtained for the
insecticide etoxazole in cotton
undelinted seed/gin byproduct
(0.05/1.0 ppm) and strawberry
(0.5 ppm) as well as
commodities such as meat and
milk (0.01 to 0.02 ppm).
(Federal Register, 9/26/03)
* Based on a request from BASF,
tolerances for the insecticide
chlorfenapyr in fruiting
vegetables. The fruiting
vegetables uses will only be for
greenhouse-grown vegetables,
and they will be found on the
Pylon label. (Federal Register,
9/26/03 and personal
communication, D. O'Byrne,

Volume III Issue 12 Berry/Vegetable Times

Powdery Mildew
Jim Mertely

Recently, powdery mildew
has been a problem in scattered
strawberry fields (and in some later-
als here at GCREC Dover). A few
words about this pathogen might be
Powdery mildew of straw-
berry is caused by the fungus
Sphaerothecia macularis f. sp.fra-
gariae. This pathogen produces su-
perficial white strands on the straw-
berry leaf which absorb nutrients
through root-like structures called
haustoria (Photo 1). Vertical shoots
(conidiophores) rise up from these
strands and end in a chain of spores
(Photo 2). Powdery mildew spores
are easily dislodged by the wind and
relatively short lived. Young leaves
are infected when temperatures are
mild and relative humidity is high.
Heavily colonized leaves respond to
infection by cupping upward, turning
purple or brown in colonized areas,
and dying prematurely (Photo 3).
Flowers and fruit may also be in-
fected. Such infections result in
flower abortion, distorted fruit, or
"seedy" fruit. Powdery mildew also
grows on the seeds when conditions
are favorable (Photo 4).
The current outbreak of
powdery mildew is the result of in-
oculum from diseased nursery plants
and favorable conditions for infection
that occurred several weeks ago.
With the crop already in the ground
and the disease already established,
chemical sprays are our only option.
Numerous products are labeled for
powdery mildew control on straw-
berry. These include the strobilurin
fungicides Abound (Quadris), Cab-
rio, and Pristine. To avoid the devel-
opment of resistance, no more than
five applications of products from
this group should be made during a
single season. The strobilurin fungi-
cides are also our best materials for
controlling anthracnose fruit rot
(Colletotrichum acutatum), which is
often a far more serious problem in
the spring than powdery mildew is in

the fall. Therefore, these fungicides
should be conserved for use later in
the season. If possible, keep your
powder dry! Nova and Procure are
highly specific products for pow-
dery mildew control that have con-
sistently controlled or suppressed
the disease in our experimental tri-
als. Hydrogen peroxide (Oxidate),
potassium bicarbonate (Armicarb,
Kaligreen), and Topsin M are also
labeled for powdery mildew control
in strawberry, but have not been in-
dependently tested for effectiveness
here. However, a discontinued
compound closely related to Topsin
M (i.e., Benlate) was moderately
effective in previous trials.
Sulfur fungicides
(Microthiol, Sulfur 6L, Thiolux,
etc.) are inexpensive, and fairly ef-
fective against powdery mildew.
Growers have decreased their use of
elemental sulfur over the years for
several reasons: availability of al-
ternatives, fear of phytotoxicity, and
suppression of predatory mites. Sul-
fur fungicides may bur strawberry
foliage when applied at high tem-
peratures, or when combined with
other materials which facilitate
penetration into plant tissues.
Therefore, sulfur should not be ap-
plied when temperatures higher than
85 F are expected within three days
of application. It is less well known
that sulfur fungicides are not as ef-
fective at temperatures below 65 F.
Do not combine sulfur with
spreader stickers or other products
containing emulsifiers or petroleum
solvents (e.g., an EC formulation).
Also, avoid the use of sulfur within
two weeks of an oil spray applic a-
tion. Modem sulfur fungicides are
produced with more uniform part i-
cle sizes than older products which
reduces the risk of phytotoxicity. If
the precautions on the label are fol-
lowed and low to moderate dosages
are applied, the risk of phytotoxicity
is low. WhenP. persimulus has
been released for two-spotted spider
mite control, sulfur fungicides
should be used sparingly. However,
Dr. Jim Price believes that one or

two applications at lower rates are
not too damaging to predatory mite
In Florida, powdery mil-
dew epidemics typically occur in
November. We may have seen the
peak of this outbreak since winter
weather has recently set in. Tem-
peratures and relative humidity
have been low since the beginning
of December. These conditions are
not favorable for powdery mildew.
Keep in mind that infected leaves
may continue to turn brown over
the next several weeks even though
S. macularis is no longer actively
growing or spreading. Although
the situation bears careful monitor-
ing, it is probably too late to start
an effective spray program for
powdery mildew this fall.

Photo 1 Haustoria

Photo 2-Conidiophores

Photo 3 Cupped leaves

Photo 4-Infected fruit

Volume III Issue 12

Berry/Vegetable Times

Volume III Issue 12 Berry/Vegetable Times

Happy Holidays

from the faculty

and staff of




Wishing you all

the best the

season can bring.

A Strawberry Farmer's

Twas the night before harvest
and all through the farm,
not a creature was stirring
till they heard the alarm.

A hard freeze was a' coming,
and all they could do
is get that water going,
sit up, and stew.

With the water's protection
the berries were fine.
The farmers were tired,
but got their pickers in line.

Soon baskets were full
and off to market they went.
To places up north is
where they were sent.

The strawberries of Florida
are a northerner's treat.
During the holiday season
they can't be beat.

So thanks to the farmers
and their hard working hands
for bringing some sweetness
to those cold barren lands.

Happy Holidays from
a Yankee turned


Volume III Issue 12

Berry/Vegetable Times

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