Group Title: Berry/vegetable times.
Title: Berry/vegetable times. September 2002.
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 Material Information
Title: Berry/vegetable times. September 2002.
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: September 2002
 Record Information
Bibliographic ID: UF00087388
Volume ID: VID00009
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.


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Berry Times

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Chemical control of Phytophthora crown rot
Dan Legard

Phytophthora crown rot can be a serious disease
in Florida. In the past, two different species of
Phytophthora (P. cactorum and P. citricola) have

Crown discoloration in
plant with Phytophthora
crown rot

Spotlight on Diagnosis
Jim Mertely

Land is already being prepared for the next berry
crop, and soon the first boxes of runner plants will arrive
from northern nurseries. Early indications are that some of
plants will be infected by Colletotrichum acutatum. This
fungus causes Colletotrichum fruit rot anthracnosee), and
is also responsible for root necrosis, poor establishment,
and other strawberry problems. How can you tell if runner
plants coming out of the box are infected? It's not easy,
but two symptoms should arouse your suspicions:

caused epidemics in Florida. The pathogen does not over
summer in Florida so the primary source of inoculum is
strawberry transplants that became infected in the nursery.
Because it can be difficult to detect the disease in the
nursery, Phytophthora crown rot problems often develop
after the daughter plants are transplanted in fruiting fields.
Two fungicides are recommended for the control
of Phytophthora on strawberry: Ridomil Gold EC
(mefenoxam) (Ridomil Gold label) which can be applied
by drip irrigation and Aliette WDG (fosetyl-al) (Aliette
WDG label) which is either used as a preplant dip or
applied to the foliage. We recommend that growers apply
Ridomil Gold (1 pt / treated acre) through their drip
irrigation system after plant establishment. A second
application may be used if symptoms of Phytophthora
crown rot appear during the season. Ridomil Gold can be
applied while plants are flowering and the PHI is 0 days.
Ridomil is very effective at controlling epidemics of
Phytophthora because it is a systemic fungicide that can
cure plants that are already infected. Growers may also
consider using Aliette WDG (fosetyl-al). However,
Aliette does not appear to be very effective at controlling
Phytophthora crown rot, although pre-plant dip
applications (2.5 lbs / 100 gals) may provide control.
Aliette is also labeled for foliar applications (2.5 to 5.0
lbs / acre) but the product would need to be applied to the
crown of the plant to provide control of the disease. It also
appears that multiple applications of Aliette (7 to 14 days
between applications) would be necessary to control the
Growers also need to consider that cultivars differ
in their susceptibility to Phytophthora root rot. Although
we have not experimentally determined the susceptibility
of different cultivars, historically, cultivars from the
University of California have been more resistant than
those from the University of Florida.

~N .~rn

Black sunken lesions
on leaf stalks

A mixture of dark and tan-
colored structural roots in
C. actutatum infected

The first symptom (sunken, black lesions) is
probably the most diagnostic. It should not be confused
with slimy rotted areas typical of plants that have been
stored improperly or for extended lengths of time. Look
for dry, sunken lesions on the petioles of younger leaves.
The second symptom can be called the "salt and pepper"
effect. Make sure that roots from runner plants, not old
mother plants, are being examined. Wash the roots and
look for a mixture of dark infected roots and tan healthy
roots. Roots that appear to be dying back from the tip or
have brown blotches may also be infected.
If you note these symptoms and would like to know
if C. acutatum is present in your planting material, we can
help. Collect at least 6 plants showing typical symptoms,
place them in a plastic bag, and bring them to the Dover
diagnostic lab a.s.a.p. It may be possible to confirm the
disease within 24 hr simply by examining the diseased
material under the microscope. However, 5-7 d may be
required if culturing is necessary to confirm the disease.

Berry Times 1


Major U.S. Strawberry Insect Problems Outside
James F. Price

Sometimes it is a struggle to successfully manage
the insect and mite problems we face in Florida and it seems
that we are the only growers burdened with this huge task.
Our warm weather and long production period help cause
these problems, but producers in other regions also have pest
control troubles just as vexing as ours. Florida growers
compete on a national scale and can benefit from
understanding production outside our own region. The
summer inter-season period is a good time to look at the
production obstacles of our competitors.
Some of the major U.S. strawberry insect problems,
not normally encountered in Florida are described below:

1. The strawberry root weevil and similar black
vine weevil are pests of strawberry produced in
perennial culture. These weevils feed on
strawberry foliage and their grub larvae feed on
roots. Just two of these insects per plant can cause
economic damage, but no satisfactory control of the
underground larvae exists. Control often is not
achieved until the perennial field is plowed under
and fumigated.

White grub of a
June beetle

2. Various white grubs of scarab beetles (including
Japanese beetles, Rose Chafer, June beetle, and
Asiatic garden beetle) cause similar damage and
are just as problematic to control. These are huge
grubs like the ones we sometimes dig up in our
yards and they are problems throughout much of the
northern production areas.
3. In the same regions, the strawberry clipper or
bud weevil causes severe damage in perennial
culture. These weevils girdle the flower pedicle
allowing the dried flower to drop to the ground.
Control is recommended when 0.6 clipped buds are
found per 2 feet of row.
4. Whiteflies, including the greenhouse, silverleaf
(sweetpotato) and banded wing whiteflies are an
increasing problem in California. The problem
has reached a point that emergency use of a new
pesticide has been required. These insects feed and
reproduce on the undersides of leaves, weaken the
plant and create sticky honeydew and the black
sooty mold that follows. Low quality fruit result.
Each of these insects resides in Florida, but none
has become problematic on strawberry here.
5. Potato leafhoppers with their toxic saliva plague

strawberries in many regions outside Florida.
Affected plants are stunted and have leaves
streaked with yellow that cause suspicions of
herbicide damage.
6. In production areas of high relative humidity
the spittlebug creates a nuisance. Nymphs feed
on leaves and flowers and exude a frothy "spittle"
mass. This activity damages the plants, but the
real loss is from the terrific annoyance to pickers.
Use your imagination.

Tarnished plant
bug a major pest
in California

7. The tarnished plant bug is a major pest of
strawberry from California to Maine. The
insect occurs in Florida, but, surprisingly, we do
not sustain economic losses. This insect inserts
its needle-like mouthparts into developing flowers
causing severe deformities in the fruit. Affected
fruit are small, cat-faced and unfit for market.
Damage can reach as high as 90%. The necessity
to apply chemicals for tarnished plant bugs
sometimes limits progress toward biological
control of spider mites. A few ago, some growers
in California used enormous tractor-mounted
vacuums to control plant bugs and to allow
survival of predator mites.
8. There are still more insect pests that the other
farmers must worry about. For instance,
strawberry rootworm (different from the
strawberry root weevil), strawberry leafroller, and
cutworm are all lepidopterous pests of strawberry
that cause concern in many regions except
Florida. And too, there is the cyclamen mite that
infrequently visits us on transplants brought from
regions that must deal with it regularly.

When the entire picture is examined, we can see that
we are not alone in having to square off against threatening
insects. Maybe we are even lucky that we have only the
menacing few.

Smoothing out the peaks and valleys in winter
strawberry production
Craig Chandler

From a labor management and marketing point of
view, it would be most desirable if strawberry growers
could harvest the same volume of fruit from their farms
each week -just as factories produce manufactured

Berry Times 2

products on a regular and consistent basis. But, because of
interactions between plants and the environment (some of
which are unpredictable), this does not happen. However, it
may be possible to smooth out the typical peaks and valleys
that occur in winter strawberry production. Listed below are
some ideas on how this might be accomplished:

1. Plant more than one cultivar. Cultivars tend to
differ from each other in their fruiting pattern, and
these different patterns can be complementary. For
example, 'Sweet Charlie' generally produces more
fruit than 'Camarosa' in February, but 'Camarosa'
produces more fruit than 'Sweet Charlie' in March.
2. Obtain transplants from more than one
propagation site or nursery. The environmental
and cultural conditions a transplant is exposed to
prior to digging can affect its fruiting pattern. For
example, transplants exposed to cool weather during
the last couple of weeks in the nursery will start to
flower and fruit before transplants that are exposed
to warm weather during the last couple of weeks in
the nursery.
3. Plant the crop over several weeks. Plants set in
early October will tend to flower and fruit before
plants set in mid to late October. But then as plants
set in early October cycle down in production, later
set blocks will often be cycling up in production.
4. Vary plant density. Higher plant densities
(accomplished by closer within row spacings) result
in higher early season yields, generally at the
expense of late season harvest efficiency and
disease control. (For more information on the
effects of plant spacing, link to the following
research paper on the GCREC-Dover web site:
"Effect of plant spacing and cultivar on the
incidence of Botrvtis fruit rot in annual
5. Use more than one transplant type. Plug
transplants tend to have a slightly different fruiting
pattern than bareroot transplants. The initial crown
size of the transplant is also important. Large crown
transplants tend to flower and fruit before smaller
crown transplants, but the fruiting cycles of smaller
crown transplants may be complementary to those
of larger crown transplants.
6. Use more than one cultural system. In the Po
Valley in Italy, strawberry growers use a
combination of open field production and plastic
tunnel production to extend their season. Plants
under the clear plastic tunnels come into production
first because of the higher soil and air temperatures
inside the tunnel, but then as the fruit production
under tunnel is cycling down, plants in the open
field are increasing in yield. In Florida, plastic
tunnels would also allow fruit to be harvested
during rainy periods, and would protect fruit from
rain damage. (Please note, however, that the
economic viability of tunnel production in west

central Florida has not yet been established.)
7. Take some acreage out of production at the end
of February or in early March. This will help
lower the major production peak that occurs in
March. Cultivars such as Sweet Charlie, Earlibrite
and Carmine lend themselves to early termination
because of their high early season yield. Blocks
planted in these cultivars can then be converted to
spring vegetable production.

Transplant storage and handling
John R. Duval

In a few weeks transplants will begin arriving in the
Plant City area for planting for the 2002-2003 strawberry
season. Most of these transplants will be set soon after
arriving; however some will need to be stored for a period of

irrigation of new

time before they are planted. Transplants should be held in
cold storage at 32 to 40 F. Once transported to the field,
plants should be planted immediately and overhead irrigation
applied as soon as possible to reduce heat stress and prevent
desiccation. If plants cannot be planted immediately, they
should be placed in a shaded spot out of the sun and
protected from the wind if possible to minimize desiccation.
Research at the GCREC-Dover has shown that reducing
stress a transplant receives before establishment can
significantly increase early yields of strawberry. By
maintaining proper storage conditions and minimizing water
and heat stress in the field strawberry plants will establish
quickly, resume growth and begin to produce berries earlier.

Center Update
Christine Manley

Another successful AgriTech meeting was held
August 27 and 28 in Plant City, and we received some
valuable feedback with our Grower Survey. We received 26
surveys back from the meeting participants who farm over
2500 acres in the area. Nearly 1800 of those acres are for
strawberries. In addition, the average number of years the
growers have been farming was 20. Other interesting
findings included the traits a grower looks for in
strawberries, which were firmness and disease and pest
resistance. All but two of the survey participants have
brought a sample to our diagnostic clinic and 100% of the

Berry Times 3

problems were properly identified and growers found the service very useful. Ever single survey noted that growers are very
interested in a Production Guide being developed, and many of the respondents agreed that a certification program for healthy
transplants would be desirable. The most popular variety last year was Camarosa partly because it has the least fruit rejections and
most attractive fruit. Over 30% of the growers were using predatory mites for spider mite control. Reasons growers didn't use
predatory mites were that miticides are effective and predators control spider mites too slowly. All but two of the participants in
our survey use drip irrigation. And when it comes to determining fertilization requirements and the rate applied, most growers use
experience as their guide. We appreciate the time each grower spent completing our survey and the information will be put to
good use. Look for complete results of our survey on our website in the near future. In addition, you will be able to access the
PowerPoint presentations and abstracts from several of the IFAS speakers.

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 named, and
does not signfy that they are approved to the exclusion of others of suitable
composition. Use pesticides safely. Read andfollow directions on the manufacturer's
The Institute of Food and Agricultural Sciences is an equal
opportunity/affirmative action employer authorized 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.

A monthly newsletter of the University of Florida Institute of Food and
Agricultural Sciences, Gulf Coast Research and Education Center, and
Florida Cooperative Extension Service
Gulf Coast Research and Education Center
13138 Lewis Gallagher Road, Dover, FL 33527
(813) 744-6630 SC512-1160
Website http//strawberry ifas ufl edu
Editors Dan Legard (legardjufl edu) & Craig Chandler (ckc). ufl edu),
Design, Layout & Distribution Christine Manley (cmanleyv ufl edu),
Director Jack Rechcaol

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