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Performance of UF strawberry cultivars
planted on three dates in October
Craig K. Chandler and James C. Sumler, Jr.
A main goal of the UF/IFAS strawberry breeding
program has been to develop cultivars that produce relatively
high yields of marketable fruit during the period from late
November to the end of February compared to cultivars
from other North American breeding programs. All the
UF/IFAS cultivars, starting with 'Florida Belle' (released in
1975) have this capability. Acceptable total season yields
have been obtained from 'Florida Belle', 'Dover', and
'Sweet Charlie' when these cultivars have been planted
anytime during the month of October, but past research at
GCREC-Dover has shown that the highest early season
yields are obtained when these cultivars are planted in early
October. Based on our experience with these older cultivars,
we have been suggesting that the new UF/IFAS cultivars --
'Earlibrite', 'Strawberry Festival', and 'Carmine' (FL 95-
256) be planted in early October. "Early October" is not
very specific, so to refine our planting-date
recommendations, we decided to conduct a trail in which
cultivars are planted on several dates, spaced a week apart,
starting October 1.
The new UF/IFAS cultivars, as well as 97-39 and
'Sweet Charlie', were planted on Oct. 2nd, 9th, and 17t, 2001.
'Sweet Charlie' plants were included in these plantings as the
standard early season cultivar.
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
Editors: Dan Legard (firstname.lastname@example.org) & Craig Chandler
(ckc&.ufl.edu); Design, Layout & Distribution: Christine Manley
(email@example.com); Director: Jack Rechcial
Plug plants from a high elevation nursery in North
Carolina were used for the Oct. 2nd planting (except for the
FL 97-39, which were "home-grown" bare-root plants).
Bare-root plants were used for the Oct. 9 and 17h plantings.
All bare-root plants, except for FL 97-39, came from the
same North Carolina source that supplied the plugs. Plants
were spaced 15 inches (38 cm) apart within the row. Ripe
fruit were harvested, graded, counted, and weighed twice
weekly from mid November till the end of February.
Although direct statistical comparisons cannot be
made between the three planting dates, there does appear to
be a trend: the later the planting date, the lower the
November-February yield (Table 1). November/December
yields appear to be higher for plants set on Oct. 9t than on
Oct. 2nd. This difference may be partially due to the fact that
bare-root transplants were used on Oct. 9t and they probably
had larger crowns than the plug plants used on Oct. 2nd.
Conversely, yields in January were higher for the October 2nd
planting than the October 9th planting. We suspect that for
early ripening cultivars like 'Sweet Charlie', plug plants may
produce lower November/December yields, but higher
January yields than bare-root plants. If true, then a grower
could include both types of plants in his farming operation
and smooth out the peaks in marketable yield from
November-January. (A future newsletter article will focus
on potential ways to better manage fruit production peaks on
a farm basis.)
Berry Times 1
The new cultivars out-yielded 'Sweet Charlie' in November/December, irrespective of planting date, but
differences in total yield were generally not detected between the cultivars in these trials. 'Earlibrite' produced
relatively large fruit, regardless of planting date (having an average fruit weight greater than 20 grams), while the other
entries had average fruit weights between 16.4 and 19.1 grams (Table 1).
Based on the data presented in Table 1, it appears the new UF/IFAS strawberry cultivars should be planted
before October 10th to obtain the highest possible November-February yield. But because year-to-year variation is
common with these types of results, several years of data will be collected and examined before specific
recommendations are made.
Table 1. Performance of UF strawberry cultivars planted on three dates during the 2001-02 season at Dover
Marketable yield (grams/plant)y
Planting date/ Average fruit
Cultivar Nov./Dec. Jan. Feb. Total weight (grams)
Carmine 180 ab 108 b 164 b 457 a 16.8 bc
S. Charlie 82 c 171 a 204 ab 457 a 17.0 be
Earlibrite 177 b 146 ab 168 b 491 a 20.1 a
S. Festival 151 b 140 ab 212 ab 503 a 16.5 c
FL 97-39 219 a 118 ab 232 a 536 a 18.1 b
Carmine 232 a 62 ab 204 bc 499 a 17.0 c
S. Charlie 102 d 92 a 166 c 360 b 16.4 c
Earlibrite 205 ab 33 b 201 bc 439 ab 21.1 a
S. Festival 163 bc 61 b 221 b 444 ab 17.2 c
FL 97-39 159 c 93 a 277 a 453 ab 19.1 b
Carmine 106 b 72 bc 152 b 330 a 16.7 c
S. Charlie 64 c 92 ab 110 c 265 a 17.1 be
Earlibrite 163 a 55 cd 170 ab 388 a 21.8 a
S. Festival 112 b 100 a 198 a 410 a 17.9 b
FL 97-39 85 bc 37 d 166 ab 397 a 17.8 bc
z All transplants, except FL 97-39, were obtained from a commercial nursery in North Carolina. Those planted on 2
Oct were plug transplants (except for the plants of FL 97-39, which were bare-root transplants), while those
planted on 7 Oct and 17 Oct were bare-root transplants.
Y At a plant density of 17,424 plants per acre, 1 gram per plant = 38.4 pounds per acre.
x Average fruit weight was determined by dividing total marketable fruit yield per plot by total marketable fruit
number per plot.
w Means based on four replications. Mean separation within columns and planting dates by Fisher's protected LSD
test, P < 0.05. (Within columns and planting dates, means followed by the same letter are not significantly
FL 97-39 were "home-grown" bare-root plants
Berry Times 2
Spotlight on Diagnosis
Last season, numerous strawberry growers in
California, Florida, and Louisiana experienced
establishment problems caused by Colletotrichum acutatum,
one of the anthracnose fungi. In the UF Strawberry
Diagnostic Lab, this pathogen was detected on at least 75 of
the 180 total samples submitted last season. Most samples
showed signs of root necrosis, the principal cause of
establishment problems, but slow decline and anthracnose
fruit rot were also diagnosed. At least one anthracnose-
infected sample was associated with each of the nursery
sources used by Florida strawberry growers. However, it
would not be accurate to suggest that all the nurseries sold
anthracnose-infected transplants last season. Disease can
spread from contaminated to healthy fields, and this may
account for some positive samples, especially later in the
season. It also looks like the foundation planting stock from
the western US was also probably contaminated by C.
acutatum. Nurserymen everywhere are now keenly aware
of the situation, and they are working with University and
private researchers to improve methods to help manage this
pathogen in the nursery. These efforts should help to
minimize problems caused by C. acutatum in the future.
IFAS pesticide revision now on-line for
James F. Price
The most recent revision of ENY-657, Insecticides,
Miticides, and Molluskicides for Management oflnsect,
Mite, Snail, and Slug Pests of Florida Strawberry, is now
available online through University of Florida EDIS. It can
be accessed for planning next season's culture through the
URL: http://edis.ifas.ufl.edu. Once there click on "Pest
Management Guides", then "Insect Management Guides",
then "Vegetables", then the above publication. This
information can also be found on our website at
ENY-657 lists the 27 active ingredients available
for Florida strawberry farmers to control insects, mites,
snails and slugs important in their crop. A list of the
commonly available commercial products along with
reentry and post harvest intervals that must be observed is
provided for each active ingredient. There is also listing of
the pests controlled by each of the products. Acramite for
spider mite control was registered too late to be included in
this revision, but is available.
Once growers know the pests to expect next season
(largely aphids, lepidopterous larvae, sap beetles, small fruit
flies, spider mites, thrips) they can select and place orders
for the desired pesticides presented in the publication.
Planning now with ENY-657 can better prepare growers for
problems that will occur during the season.
Results of the 2001-2002 Botrytis fruit
rot fungicide efficacy trial
Dan Legard, Steve MacKenzie and James Mertely
This month we will review the results of our
Botrytis fruit rot fungicide efficacy trial. We conduct these
trials every season to evaluate new fungicides and compare
them to fungicides that growers currently use. Although we
had a very unusual season with record high temperatures in
January (http://fawn.ifas.ufl.edu) and a delay in the peak
harvest period of several weeks for most cultivars, there was
a period during the season when conditions were ideal for an
epidemic of Botrytis fruit rot. The incidence of Botrytis
began to increase in January, was most severe during mid to
late February, and declined during early March (Figure 1).
This pattern is typical for Botrytis epidemics in Florida,
repeating itself with slight variations every season.
The fungicides that best controlled Botrytis in our
study included the labeled products Switch, Elevate,
Captan and Thiram. However, a couple new products
looked promising. These were a strobilurin (same chemical
class as Quadiis ) from BASF (BAS 516) and a new
product from Arvesta (formally Tomen Agro) that combines
Captan and Elevate. The best control programs in our
study combined weekly applications of a protectant like
Captan or Thiram with four bloom applications of Switch
or Elevate The bloom applications were applied weekly
from January 23 to February 13, protecting the flowers from
infection when disease pressure was highest. The best
control programs in our study combined weekly applications
of a protectant like Captan or Thiram with four bloom
applications of Switch or Elevate The bloom
applications were applied weekly from January 23 to
February 13, protecting the flowers from infection when
disease pressure was highest.
Berry Times 3
More information about the control of Botrytis fruit rot and the scheduling of bloom applications can be found on our website
Over the next few months, the facilities at GCREC-Dover will be undergoing several renovations. The work is
being paid for by funds the Florida legislature generously appropriated to renovate the strawberry lab. New growth
chambers are now being installed in a new equipment room. We will also be repairing the air handlers in both buildings.
One of the most important projects is the field renovation, in which we will change the field layout to increase the cultivated
area and install a new computer controlled irrigation system. A new climate controlled greenhouse is also in the planning
stage. Our new and improved research facilities will allow our faculty and staff to better serve the needs of the strawberry
On a personal note, the faculty and staff would like to congratulate Dr. John Duval on his recent nuptials. Dr.
Duval and his lovely wife, Jennifer, were wed in Key West May 20. Best wishes to the new bride andgroom.
Figure 1. Percent Botrytis fruit rot during 2001-2002 season
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 signify that they are approved to the exclusion of others of suitable composition. Use pesticides safely. ,, directions
on the manufacturer's label.
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