• TABLE OF CONTENTS
HIDE
 Front Cover
 Field map
 Program
 Table of Contents
 Welcome and introduction
 Current list of program leader...
 Main
 Strawberry field tour
 Acknowledgement of industry for...
 Map to AREC-Dover






Group Title: Strawberry field day.
Title: Strawberry field day. February 10, 1993.
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Permanent Link: http://ufdc.ufl.edu/UF00076494/00009
 Material Information
Title: Strawberry field day. February 10, 1993.
Series Title: Strawberry field day.
Alternate Title: Research report - Dover, Florida Agricultural Research and Education Center ; DOV 93-1
Physical Description: Serial
Language: English
Creator: Albregts, E. E.
Chandler, C. K.
Waters, W. E.
Publisher: Agricultural Research Center, Institute of Food and Agricultural Sciences, University of Florida
Publication Date: 1993
 Record Information
Bibliographic ID: UF00076494
Volume ID: VID00009
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 143121533

Table of Contents
    Front Cover
        Front Cover
    Field map
        Page i
    Program
        Page ii
    Table of Contents
        Page iii
        Page iv
        Page v
        Page vi
    Welcome and introduction
        Page 1
    Current list of program leaders
        Page 2
    Main
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
    Strawberry field tour
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
    Acknowledgement of industry for the research programs at AREC-Dover
        Page 21
    Map to AREC-Dover
        Page 22
Full Text



SResearch Report 93-1
Dover AREC Research Report DOV 93-1


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AGRICULTURAL RESEARCH AND EDUCATION CENTER
INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES
UNIVERSITY OF FLORIDA

13138 Lewis Gallagher Road
Dover, FL 33527-9664

February 10, 1993

STRAWBERRY FIELD DAY PROGRAM

Contact Person: Dr. Earl E. Albregts


MODERATOR:


Time, PM

2:15

2:20


2:30

2:40

2:50

3:00

3:15

3:25

3:40

3:45


Dr. Tim Crocker, IFAS, Department of Horticultural Sciences



Dr. W. E. Waters Welcome and Introductory Comments

Dr. N. P. Thompson, Acting Dean for Research
Update of IFAS Research Programs

Dr. E. E. Albregts Nutrition and Culture

Dr. J. F. Price Insect Management

Dr. M. van de Vrie Biological Control of Spider Mites

Drs. G. A. Clark and C. D. Stanley Water Research

Dr. C. K. Chandler Cultivar Development

Dr. Jeffrey Brecht Post-harvest Studies

COFFEE/BERRY BREAK

TOUR OF RESEARCH PLOTS

Mite Management J. F. Price and M. van de Vrie.
Irrigation G. A. Clark and C. D. Stanley
Plant Breeding C. K. Chandler
Culture E. E. Albregts


Field Day Host and Tourguide:

Dr. Tim Crocker, IFAS, Department of Horticultural Sciences


*************************f*********ffff*









TABLE OF CONTENTS

Page

Welcome and Introduction ...................................... ...... 1

List of Program Leaders ............................................. 2

USPS Employees .................................................... 2

Strawberry Research Accomplishments

MITE MANAGEMENT

Establishment of Biological Control of Twospotted Spider Mite
on Commercial Farm .......................................... 3

Dispersal of Phytoseiulus persimilis, Predator of Twospotted
Spider Mite .................................................. 3
Stability of the Predator/Prey System ........................... 3

Strawberry Cultivar Effects on the Twospotted Spider Mite ........ 3

Influence of Insecticides on P. persimilis under Field
Conditions ................................................. 3

STRAWBERRY BREEDING PROGRAM

New Cultivars Released ......................................... 3

Current Breeding Work ......................................... 4

WATER MANAGEMENT

Tailwater Recovery and Reuse for Overhead Irrigation ............. 5

Management of Drip Irrigated Strawberries ........................ 5

Water Requirements of Strawberry Plants ......................... 6

STRAWBERRY CULTURE

Evaluation of Mulch Color for Fruiting Strawberry ................ 6

Defoliation of Strawberry Transplants for Fruiting Field ......... 6

Preplant Fertilization for Drip Irrigated Strawberry ............. 7

Container Plants for Strawberry Fruiting Field ................... 7








POSTHARVEST BIOLOGY AND TECHNOLOGY

Modified Atmosphere Packaging for Strawberries ................... 7

Comparison and Combination of Irradiation and Modified
Atmosphere Packaging for Storage of Strawberries ................. 7

Evaluation of Hydrocooling for Postharvest Handling of
Strawberries ............................................... 8









POST HARVEST STUDIES
Pane
Field Tour

Nitrogen Rates for Microirrigated Strawberry E. E. Albregts, G. J.
Hochmuth, G. A. Clark, and C. D. Stanley ........................ 10

Potassium Rates .for Microirrigated Strawberry E. E. Albregts, G. J.
Hochmuth, G. A. Clark, and C. D. Stanley ........................ 10

Osmocote Microirrigated Study E. E. Albregts ........................ 11

Effects of Pesticides on Predaceous Mites M. van de Vrie and J. F.
Price ....................................................... 11

Dispersal of Predaceous Mites in Commercial Strawberry Fields M. van
de Vrie and J. F. Price ........................................ 12

Comparison of Effectiveness of Two Species of Predaceous Mites,
Phytoseiulus persimilis and Ph. macropilis Under Field Conditions
M. van de Vrie and J. F. Price ................................ 12

Comparison of Plant Performance Under "Biological" and "Chemical"
Treatment M. van de Vrie and J. F. Price ...................... 12

Influence of Strawberry Cultivars and Breeding Lines on Spider Mite
Reproduction and Spider Mite Damage M. van de Vrie, C. K.
Chandler, J. F. Price, C. H. Schanks, J. Scheerens, M. Pritts
and C. Hoffman .............................................. 13

Demonstration of Biological Control of Twospotted Spider Mite
at AREC-Dover Center M. van de Vrie and J. F. Price ............ 13

Response of Twospotted Spider Mites to Miticides J. F. Price ......... 14

Response of Insect Pests to Experimental Insecticide, TD2321 J. F.
Price ....................................................... 14

Reduced Water Applications with Overhead Irrigation Establishment of
Fruiting Strawberry Plants G. A. Clark, E. E. Albregts and
C. D. Stanley ............................................... 15

Phosphorus Rates for Fruiting Strawberry E. E. Albregts .............. 16

Plant Density for Four Strawberry Cultivars E. E. Albregts ........... 16

Canadian Grown vs. Florida Grown Transplants E. E. Albregts .......... 17

Variety Trial C.K. Chandler and E.E. Albregts ....................... 17

Observational Trial C.K. Chandler ................................... 18

Row Trial C.K. Chandler .......................................... 18








Pane


Seedling Trial C.K. Chandler ........................................ 18

Fungicide Trial T. E. Crocker and C. K. Chandler .................... 19

'Oso Grande' Spacing Trial C. A. Sims, R. B. Bates, and C. K.
Chandler ..................................................... 19

Evaluation of Fragaria Clones for Resistance to Spider Mites C. H.
Shanks, Jr. (Washington State Univ.), C. K. Chandler, M. van de
Vrie, and J. F. Price ......................................... 19

Early Planting Trial C. K. Chandler ................................ 20


Acknowledgements .................................................. 21









WELCOME AND INTRODUCTION


W. E. Waters, Center Director

On behalf of the faculty and staff, I extend to each of you a most cordial
welcome to the Dover Agricultural Research and Education Center Field Day. The
Center was initiated in 1927 as a one-man operation located southeast of Plant
City. In 1963, the Center was moved to its present location, and the programs
were expanded. This Center, with an affiliated Center located in Bradenton, is
a Research and Education unit of the University of Florida's Institute of Food
and Agricultural Sciences.

In Dover and Bradenton, 7 research scientists and 1 extension specialist
participate in strawberry research and extension programs. Each research
scientist also holds a joint appointment with his subject matter department at
the University of Florida. This combination of a broad base of research
disciplines, industry contacts and an excellent faculty makes the
interdisciplinary cooperative team approach to research problems far more
productive than could otherwise be accomplished with limited investments in
independent programs.

The overall mission of these centers deals directly with the strawberry industry
in Florida through research programs in (1) genetics, breeding and cultivar
development and evaluation; (2) biological, chemical and mechanical pest
management for diseases, insects, nematodes, and weeds; (3) production
efficiency, culture, fertilization, management and environmental stress; (4)
mechanization, harvesting, handling, and postharvest physiology systems; (5)
water management and conservation; (6) advancement of basic knowledge of the
various scientific disciplines represented by the faculty; and (7) assistance to
the cooperative extension service, departments in the College of Agriculture and
other research centers with extension, educational training and cooperative
research programs for the benefit of producers, consumers and students.

Information presented in this publication summarizes the active research and
extension projects under way this season on strawberries. We sincerely
appreciate your interest and support of these programs, and continuously solicit
your suggestions for improvement, and welcome input concerning industry needs to
keep our research and extension programs productive.








CURRENT LIST OF


Albregts, Earl E.


Chandler, Craig K.


Clark, Gary A.


Gilreath, James P.


Price, James F.


Stanley, Craig D.

Waters, Will E.


Vacant


PROGRAM LEADERS, APPOINTMENT DATE, AND AREA OF
SPECIALIZATION AND LOCATION

1967. Soil Scientist. Local administration, soil and
plant nutrition and culture of strawberry and vegetable
crops, AREC-Dover.

1987. Associate Geneticist and Plant Breeder.
Genetics, plant breeding, and development of strawberry
cultivars, AREC-Dover.

1986. Associate Extension Water Management Specialist.
Extension education and cooperative research on
vegetable and ornamental crops, GCREC-Bradenton.

1981. Associate Horticulturist. Weed control of
vegetable and ornamental crops, GCREC-Bradenton.

1978. Associate Entomologist. Identification, biology
and control of insects and mites of ornamental and
strawberry crops, GCREC-Bradenotn.

1979. Associate Soil Scientist. Soil-water relations
for ornamental and vegetable crops, GCREC-Bradenton.

1960. Horticulturist and Center Director.
Administration, soil and plant nutrition, and
horticulture, GCREC-Bradenton.

Plant Pathologist. Etiology and control of strawberry
and vegetable diseases, AREC-Dover.


UNIVERSITY SUPPORT PERSONNEL SYSTEM STAFF


Annie F. Turgeau
Alicia J. Whidden
James C. Sumler
Larry J. Smith
Frederick D. Wenzel
Michael C. Murphy
Vacant


Secretary
Biological Scientist
Biological Scientist
Agricultural Assistant Supervisor
Senior Agricultural Assistant
Agricultural Assistant
Agricultural Assistant









MITE MANAGEMENT
J. F. Price and M. van de Vrie

Establishment of Biological Control of Twospotted Spider Mite on Commercial
Farm. Release of the predatory mite, Phytoseiulus persimilis at an early
stage of spider mite population development resulted in maintenance of
spider mites below economically damaging levels, provided no hazardous
pesticides were applied.

Dispersal of Phytoseiulus persimilis, Predator of Twospotted Spider Mite.
Dispersal of this predator, under field conditions, is performed by early
stage immature forms carried by air currents.

Stability of the Predator/Prey System. When P. persimilis has reduced the
spider mite prey population to non-damaging levels, a balance is
established between spider mites and predators, such as Scymnus sp.,
lacewing larvae and predatory midge larvae.

Strawberry Cultivar Effects on the Twospotted Spider Mite. Rate of spider mite
reproduction and development and sex ratio of spider mite offspring were
not variously affected by leaves of numerous strawberry cultivars. Spider
mite populations among plants of those cultivars may be affected, however,
by variations in leaf area.

Influence of Insecticides on P. persimilis under Field Conditions. Malathion
and diazinon, used at recommended rates on strawberries caused some
mortality in the mobile stages of P. persimilis, however, the population
was able to recover because the eggs were unaffected. Motile forms of P.
persimilis are killed by certain formulations of captain but not by the 50
WP formulation.

STRAWBERRY BREEDING PROGRAM
C. K. Chandler

New Cultivar. On June 23, 1992, the IFAS cultivar release committee approved
the release of FL 85-4925, and named this clone 'Sweet Charlie'. FL 85-
4925 was named 'Sweet Charlie' to honor Professor Charles M. Howard. Dr.
Howard worked at the Dover Center from 1967 until his death in October
1991. He was in charge of the breeding program for 20 years, until 1987,
and in 1986 he selected the seedling that eventually led to the new
cultivar.

Florida Foundation Seed Producers, Inc., a non-profit organization whose purpose
is to handle the propagation and sale of IFAS cultivars, has applied for
a patent on 'Sweet Charlie', and has designated the Florida Strawberry
Growers Association (FSGA) to be its production and distribution agent.
FSGA is responsible for licensing nurseries to propagate the new cultivar
and is also responsible for collecting royalties.

Over 100,000 plants of the cultivar, from Research Center stock, were
distributed to nurserymen during the spring and early summer of 1992. An
estimated 200 to 300 acres of 'Sweet Charlie' are growing in fruiting
fields this season which is a small percentage of the total Florida
acreage but this should give the industry a good idea of the cultivar's
potential.








IFAS has high hopes for 'Sweet Charlie'. It is complimentary to the principal
cultivars now being grown in west central Florida. Currently, 'Selva' and
'Oso Grande' occupy the majority of west central Florida strawberry
acreage. 'Selva' is very early fruiting, usually producing some fruit in
November, but the fresh fruit flavor of this cultivar is marginal. 'Oso
Grande' produces fruit with better fresh fruit flavor, but is 4 to 6 weeks
later than 'Selva'. 'Sweet Charlie' from northern latitude nurseries is
only 2 to 3 weeks later than 'Selva' and has outstanding fresh fruit
flavor.

In a taste test conducted at the Gulf Coast Research and Education Center in
Bradenton, 26 out of 32 participants rated 'Sweet Charlie' fruit superior
to that of 'Selva' and 'Oso Grande' for flavor.

In laboratory analyses, Jeff Brecht, an IFAS postharvest physiologist, found
that 'Sweet Charlie' fruit had a higher concentration of sugars and
vitamin C and lower acidity than fruit of 'Selva' and 'Oso Grande'.

As for its productivity in commercial fields: three growers reported yields of
approximately 3000 flats/acre during the 1991-92 season.
Summarizing the strengths of 'Sweet Charlie': it is early fruiting, productive,
resistant to anthracnose, and produces fruit with excellent flavor.

Its major weakness is its susceptibility to Botrytis and Dendrophoma fruit rot.
The best way to minimize these rots is to apply protectant fungicides
regularly, especially during periods of cloudy, humid conditions and warm
weather. It may also be helpful to harvest 'Sweet Charlie' every 2 to 3
days when daytime temperatures are in the 80's or night temperatures are
in the 60's.

Other problems encountered include catfaced fruit on the first "hand" of locally
propagated plants; albino fruit on plants exposed to high levels of
nitrogen fertilizer; cracking of fruit after a rain; and at times berries
are produced on which the seeds rub off easily.

Despite these problems, IFAS believes that 'Sweet Charlie' can help improve the
image of Florida strawberries. West central Florida brokers can sell
strawberries even if they lack flavor because of the market window that
the climate gives them but with 'Sweet Charlie', they have a berry
consumers will buy, not because it's the only strawberry in the market,
but because it tastes good.

Current Breeding Work. The major goal of the breeding program continues to be
to develop cultivars that are resistant to anthracnose, spider mites, and
Dendrophoma and Botrytis fruit rot, are easy to harvest, and produce
large, firm, attractive, and flavorful fruit.

About 130 selections and 15,000 seedlings are currently being evaluated.
Several selections looked particularly promising during the 1991-92
fruiting season. FL 87-236 (selected in 1988) had impressive marketable
yield (>3500 flats/acre through the end of March in one trial) and average
fruit size comparable to 'Oso Grande'. Two 1990 selections, number 15 and
51, ranked well above 'Oso Grande' and 'Selva' for fruit attractiveness in









a small-plot observational trial conducted during the 1991-92 season. Both
selections are being evaluated more extensively this season.

During the past several seasons, Jim Price and Marinus van de Vrie have
evaluated advanced selections for mite resistance. Preliminary studies
indicate that 'Sweet Charlie' is significantly more resistant to
twospotted mite than 'Selva'.

In conclusion: the 'Sweet Charlie' cultivar should be a useful addition to the
cultivars presently grown, and as far as the current breeding program is
concerned, '236', '15', '51' and a host of other selections are being
systematically evaluated.

STRAWBERRY WATER MANAGEMENT RESEARCH AND EXTENSION PROGRAM
G. A. Clark, C. D. Stanley, and E. E. Albregts

Tailwater recovery and reuse for overhead irrigation. Objectives: 1) Determine
reductions of deep well withdrawals due to use of recovery system; 2)
Determine impact on storage pond water quality due to leached nutrients;
3) Develop a computer program to simulate long term use of the system; 4)
Develop computer program for pond design to accommodate freeze protection,
5) Perform a simple economic analysis of fixed and operating costs of the
system.

Accomplishments. 1) Results showed that reductions in deep well pumping from
use of a tailwater recovery system ranged from 50-70% (avg. 63%) depending
on location, pond management, and season. 2) Water quality evaluations
showed seasonal changes in nitrate concentration in storage pond to be
very low (primarily surface runoff). However, previous studies showed
higher amounts occurred from systems using subsurface drain tiles. 3)
Impact of system use for crop protection during freeze events showed
predictable runoff amounts depending on duration of application. 4)
Computer programs for pond design and behavior were developed

Recommendations. 1) Need proper sizing, design and location of storage pond to
be successful for desired operations, 2) Consider system as rainfall
harvest system, 3) Keep pond level low unless use is required (allows
subsurface flow into pond) 4) Make sure you are in compliance with state
and local regulations concerning retention pond construction (wetlands
issues)

Management of drip irrigated strawberries. Objective: Determine appropriate
soil tension threshold level using tensiometers for moisture management
and irrigation scheduling. Tension thresholds of 5, 10, and 15 centibars
(cb) were used.

Accomplishments. 1) Fruit yield and size were not affected by tensiometer
setting, 2) Seasonal drip irrigation water applications were lower with
tensiometer settings of 10 and 15 cb than with 5 cb, 3) Monthly water
requirements from the 10 cb treatment ranged from 0.6 inches in December,
to 1.3 inches in February, to 2.4 inches in April.

Recommendations. 1) Tensiometers should be used as irrigation management tools
in drip irrigated strawberry production. 2) Place tensiometers 6 inches
deep positioned between the drip tube and the plant. 3) Adjust irrigation








schedules to maintain soil tensions no drier than 10 cb prior to the next
irrigation cycle.

Water requirements of strawberry plants. Objectives: 1) Determine the plant and
field level water requirements needed in the growth and development of
strawberry plants. 2) Determine crop water use coefficients (kc) for use
with different reference evapotranspiration (ETo) estimation methods for
irrigation scheduling and water budgeting purposes.

Accomplishments. 1) Strawberry monthly crop water requirements were determined
from three years of lysimeter data. Plant level water use averaged: 0.5
inches per month for Nov. and Dec.; 0.9 inches per month for Jan. and
Feb.; and 2.0 inches per month for Mar. and Apr. Field level water use
(plants and row middles) averaged: 1.0 inch per month for Nov. and Dec.;
1.5 inches per month for Jan. and Feb.; and 3.2 inches per month for Mar.
and Apr. 2) Four ETo methods were used with measured weather data to
determine the monthly kc values for each of the ETo methods.

Recommendations. 1) Develop an appropriate irrigation schedule and water budget
based on plant needs and growth characteristics, climatic conditions, soil
moisture conditions, and irrigation system characteristics.

STRAWBERRY CULTURE
E. E. Albregts

Evaluation of Mulch Color for Fruiting Strawberry. During 3 fruiting seasons,
black polyethylene mulch was painted with either an oil or water base
paint. The black polyethylene was painted brown, blue, green, orange,
red, white, and yellow or remained black. 'Selva', 'Chandler', and
breeding line FL-79-1126 were set in all beds. Fruit yields to March 1
were always significantly greater with the yellow painted mulch than with
the black mulch. The red and orange and especially the white painted beds
gave higher early yields each season but yields were not always
significantly higher. Numerically, the black mulch gave the lowest early
yield each season. Beds with the yellow and white mulches generally were
above average in fruit number, average fruit weight, and percent
marketable fruit before March 1. Seasonal yields showed no consistent
yield trends. Soil temperatures at the 1" and 4" depths in the bed were
warmest with the black mulch and coolest with the white and yellow
mulches.

Defoliation of Strawberry Transplants for Fruiting Field. Florida clones
'Dover' and FL-79-1126 grown in nurseries at AREC-Dover, and California
clones 'Chandler' and 'Selva' grown in Canada were evaluated in the
fruiting field. Transplants were defoliated just prior to planting so 0%,
35%, 60%, or 87% of the foliage was removed. Some 'Chandler' plants were
also defoliated at the 87% level 2 weeks prior to plant harvest. With
Florida grown plants, early fruit yields (through January) and total
yields decreased with increasing amounts of defoliation. 'Chandler' and
'Selva' plants from Canada gave a similar response. Average fruit weight
also decreased with increasing defoliation. The percent of the cull fruit
rated cull because of small size increased with increasing defoliation.
The negative fruiting responses may be related to plants being smaller
throughout the season with increasing defoliation.








Preplant Fertilization for Drip Irrigated Strawberry. Strawberry was grown for
2 seasons with a preplant 19-0-19 granular fertilizer applied at 0, 100,
200, 300, and 400 Ibs/acre and banded above the drip tube. Phosphorus and
micronutrients were applied broadcast before bed preparation. Additional
nitrogen and potassium were applied through the drip tube at the rate of
one pound/acre/day and applied twice weekly. Fertilization with the drip
tube started one month and one week after transplanting during the first
and second seasons, respectively. Total marketable fruit yields and
marketable fruit/plant were not affected by preplant fertilizer rate.
During the first season, plants were larger and the percent marketable
fruit increased with increasing rate of fertilizer, but not during the
second season. Average fruit size increased with fertilizer rate the
first season but decreased the second season. Preplant fertilization is
probably not needed if fertilizer is injected through the drip as soon as
new roots are evident, usually within a week after transplanting.

Container Plants for Strawberry Fruiting Field. Locally grown 'Oso Grande' and
'Sweet Charlie' plant tips were placed in 2" x 2" x 2" planting
containers, established and given 1 or 2 weeks of chilling (33 to 360F).
Plants were then given 2 weeks to acclimate to the hot weather and were
set into the fruiting. This procedure was conducted twice with plants
set into the fruiting field on 10/11/91 and 10/28/91. A third treatment
was the setting of normal size nursery plants into large planting
containers which were 2" x 2" x 6" deep. 'Oso Grande' plants were not
used on the first date for the third treatment. The 10/11/91 planting
gave greater yield than the 10/28/91 planting throughout the season. The
2 week chilled plants gave double the yield of the one week chilled plants
during December and for the season. For the second planting date, 'Oso
Grande' yields decreased with chilling and 'Sweet Charlie' yields
increased with chilling. Fruit of the 10/11/91 planting date were larger
than those of the 10/28/91 planting date.

POSTHARVEST BIOLOGY AND TECHNOLOGY
J. K. Brecht
Modified Atmosphere Packaging for Strawberries. Experiments were conducted in
1990 and 1991 with a graduate student, P. C. Talasila, and Dr. K. V. Chau
of the Agricultural Engineering Department. Respiration of harvested
'Selva' strawberries was measured as a function of storage temperature and
02 and CO2 concentrations in the atmosphere. The resulting data was used
to develop a model that can be used to design modified atmosphere
packaging systems. However, it was found that no commercially available
films exist that would allow establishment of the low 02 and high CO2
concentrations desired for strawberries.

Comparison and Combination of Irradiation and Modified Atmosphere Packaging for
Storage of Strawberries. These experiments were carried out in 1992 with
Dr. J. A. Bartz of the Plant Pathology Department, Dr. S. A. Sargent of
Horticultural Sciences, and a graduate student, J. P. Emond, and Dr. K. V.
Chau of Agricultural Engineering. We ran several tests using the
Vindicator irradiation facility in Mulberry to investigate the
effectiveness of irradiation (IRR) and modified atmosphere packaging (MAP)
for control of postharvest decay organisms and maintenance of fruit
quality, as well as the possibility of synergism when the treatments are
used in combination. We used a MAP system that relies on restricted gas








exchange through a perforation in an otherwise impermeable film to
establish the desired atmosphere.

Irradiation effectively controlled rhizopus rot but not gray mold when
strawberries were stored at 45F for 1 to 1-1/2 weeks followed by 2 or 3
days at 68F; simply holding strawberries at near optimum storage
temperature (34F) was as effective as IRR in controlling decay. Modified
atmosphere packaging was more effective than IRR in controlling decay in
34F storage and the two treatments were equally effective at 45F. Both
IRR and MAP improved marketability at 45F storage temperature, but only
MAP improved marketability at 34F storage. There was inconsistent
evidence for synergism between IRR and MAP. Irradiation caused some
softening of strawberries while MAP helped retain firmness.

It appears from the results of these experiments that IRR will be most
useful when higher than optimum storage temperatures are encountered,
resulting in more potential problems with rhizopus rot than gray mold.
The MAP was also useful at the higher storage temperature (45F), but
dramatically extended storage life of strawberries when combined with low
storage temperature (34F). We stored strawberries for 4 weeks at 34F in
MAP with good retention of marketability, meaning that the quality would
be much better than strawberries stored in air at any point in the normal
marketing period.

Evaluation of Hydrocooling for Postharvest Handling of Strawberries. Potential
changes in the handling system for strawberries involving postharvest
sorting and grading, or use of recyclable plastic flats, may allow the use
of hydrocooling, a faster precooling method than the currently used forced
air cooling. However, increased decay and watersoaking are potential
problems associated with hydrocooling of some commodities. Therefore,
tests were conducted with a graduate student, J. J. Aracena, and Dr. S. A.
Sargent of the Horticultural Sciences Department to evaluate the effects
of hydrocooling on strawberries.

'Selva' strawberries were hydrocooled using 32F water until pulp
temperatures of the fruit reached 36F or 46F, then the fruit were stored
in cold rooms at 34F or 45F for 8 days. Control fruit were air cooled in
the same cold rooms. Hydrocooling reduced water loss compared to air
cooling. This was due to water uptake during the hydrocooling process,
but no symptoms of watersoaking were observed after storage. There was no
difference in decay incidence between hydrocooled and air cooled
strawberries. Overall, we saw no inherent negative effects of
hydrocooling on strawberry quality.

These results indicate that evaluation of hydrocooling as a potential
component of modified strawberry handling systems should continue. These
evaluations will have to include tests run under conditions of high
pathogen load, and with different commercial hydrocooler configurations
before we can recommend hydrocooling to Florida growers.


















STRAWBERRY FIELD TOUR









Nitrogen Rates for Microirrigated Strawberry
E. E. Albregts, George Hochmuth, Gary Clark and Craig Stanley


Location:

Objective:


Clones:


Treatments:







Operation:







Summary:


Block A


To evaluate N rates with microirrigation on strawberry growth
and fruiting response.

Oso Grande on south end and Seascape on north end (both from
Canada). Transplanted on October 14, 1992.

Nitrogen Rate
Plot No. Ibs N/day by microirriqation

1 0.25
2 0.50
3 0.75
4 1.00
5 1.25

Phosphorus, magnesium, and micronutrients were broadcast at
bedding. All N applied through microirrigation at rates shown
above on a weekly schedule. Plant growth and color are being
monitored periodically as well as the N and K content of the
foliage. Leaf sap N & K are also being determined. Fruit
yield and quality data will be taken at harvest. Rainbird
drip tube microirrigation tubing with an emiter spacing of 9
inches and a discharge rate of .5 gallons/minute/100 ft.

Nitrogen rates of 1/2 to 3/4 Ibs/acre were optimum during the
1990-91 season.


Potassium Rates for Microirrigated Strawberry
E. E. Albregts, George Hochmuth, Gary Clark and Craig Stanley


Location:

Objective:


Clones:


Treatments:


Block A


To evaluate K rates with microirrigation on strawberry growth
and fruiting response.

Oso Grande on south end and Seascape on north end (both from
Canada). Transplanted on October 14, 1992.

Potassium Rate
Plot No. Ibs K/day by microirriqation

1 0.25
2 0.50
3 0.75
4 1.00
5 1.25








Operation:







Summary:


Phosphorus, magnesium, and micronutrients were broadcast at
bedding. All K applied through microirrigation at rates shown
above on a weekly schedule. Plant growth and color are being
monitored periodically as well as the N and K content of the
foliage. Leaf sap N & K are also being determined. Fruit
yield and quality data will be taken at harvest. Rainbird
microirrigation tubing with an emiter spacing of 9 inches and
a discharge rate of .5 gallons/minute/100 ft.

Potassium rates of 1/4 Ibs/acre were optimum during the 1990-
91 season.


Osmocote Microirrigation Study
E. E. Albregts


Location:

Objective:


Clones:


Treatments:


Operation:






Summary:


Block A


To determine fruiting response of strawberry to two fertilizer
sources.

Oso Grande south end (Canada) and Sweet Charlie north end
(AREC-Dover). Transplanted on October 14, 1992.

Plot No. Treatment

1 All granular N & K from KC1 and NH4NO3
2 All liquid N-K-P fertilizer from Peters 17-5-30
3 All liquid N & K fertilizer from KC1 and NH4NO3
4 All granular N, K, & P from Peters 16-4-16
5* Granular + liquid N & K fertilizer from KC1 and
NH4NO3

Nitrogen rates are 200 Ibs/acre. Phosphorus rates are 50
Ibs/acre PO0s except for treatment 2 with 59 Ibs P20O acre.
Potassium is 165 Ibs K/acre except for treatment 2 which has
145 Ibs/acre of potassium as K. All liquid fertilizer was
applied once weekly through microirrigation system. All
granular fertilizer applied above drip tube one inch below
soil surface.

Work in progress.


Effects of Pesticides on Predacious Mites
M. van de Vrie and J. F. Price


Location:

Objective:


Block D


To determine the effects of fungicides, insecticides and
miticided on predacious mites in various stages of their
development.








Operation:




Summary:


Small plots of strawberry plants were infested with twospotted
spider mites in December 1992. Predacious mites were released
in January 1993. Various pesticides are being applied and
their effects on the entire mite population is recorded by
inspecting leaf samples.

Work in progress.


Dispersal of Predacious Mites in Commercial Strawberry Fields
M. van de Vrie and J. F. Price


Location:

Objective:


Block D


To study the dispersal and the
predacious mites and relate this to
mite population development.


searching capacity of
their effect on spider


Operation:



Summary:


Potted plants with or without spider mites will be placed in
a field where the twospotted spider mite is under biological
control. After an exposure time of 48 hours the leaves will
be inspected for the presence of prey and predators.

Work in progress.


Comparison of the Effectiveness of Two Species of Predacious
Mites Phytoseiulus persimilis and Ph. macropilis under Field Conditions
M. van de Vrie and J. F. Price


Location:

Objective:




Operation:


Results:


Block D; 4 beds west

To determine the capacity of reducing two spotted spider mite
populations by the two predacious mite species Phytoseiulus
persimilis and Ph. macropilis. This last species is a locally
occurring species and may have some advantages over Ph.
persimilis.

Host plants were inoculated artificially with spider mites in
December 1992 and predators were released twice in January
1993.

Work in progress.


Comparison of Plant Performance Under "Biological" and "Chemical" Treatment
M. van de Vrie and J. F. Price


Location:

Objective:


Block D


To determine reduced plant performance as is often observed
under a chemical spray program and its effect on productivity.








Operation:





Summary:


Eight strawberry varieties are planted in four randomized
blocks. Two blocks are under "biological", and two are under
"chemical" control. Counting the number of leaves and
measuring the average leaf area may show the effect of the
treatment. Productivity of the plants is determined by
counting and weighing the berries.

Work in progress.


Influence of Strawberry Cultivars and Breeding Lines on
Spider Mite Reproduction and Spider Mite Damage
M. van de Vrie, C. K. Chandler, and J. F. Price


Location:

Objective:



Treatments:






Operation:





Summary:


Block D


To determine the effects of eleven strawberry cultivars and
breeding lines on twospotted spider mite reproduction, and
longevity and to study the reaction of these plants to spider
mite feeding activity.

Eleven cultivars and breeding lines:
A 16 WSU 2202
E 15 G 9
GCL 8 M 1
Totem X 11
WSU 2198 RCP 37
CL 5

Leaves from these plants will be used in laboratory
experiments to determine rate of reproduction, juvenile
mortality and longevity of the twospotted spider mite.
Severity of mite damage will be studied under field conditions
and on isolated leaves on potted plants in greenhouse
experiments after mite inoculation.

Work in progress.


This is a project in cooperation with Dr. J. Scheerens, Ohio Agricultural
Research & Development Center; Dr. M. Pritts, Cornell University; Dr. C. Hoffman,
Driscoll Strawberry Associates; Dr. C. H. Shanks, Washington State University,
under the title "Evaluation of Fragaria clones for resistance to spider mites in
various regions of the United States".

Demonstration of Biological Control of Two Spotted Spider
Mite at AREC/Dover Center
M. van de Vrie and J. F. Price


Entire Dover AREC Center


Location:









Objective:


Treatment:

Operations:




Summary:


Establish biological control of the two spotted spider mite on
the AREC Dover Center using Phytoseiulus persimilis predatory
mite and no miticides during the entire production season.

Phytoseiulus persimilis was released on November 29, 1992 at
a rate of 1 mite per plant.

Major fields are scouted weekly according to a special rating
system. Other pests as aphids and worms are recorded at the
same procedure. Corrective sprays were applied on three spots
prior to the predator release because of the high mite density
at the beginning of November 1992.

The spider mite population has been under biological control
since the middle of December 1992. Scouting will be continued
during the entire season.


Response of Twospotted Spider Mites to Miticides
J. F. Price


Location:

Objective:


Treatments:


Operation:


Summary:


Block D


To determine the response of twospotted spider mites, their
eggs and strawberry fruit yield to applications of currently
available and one miticide not yet registered on strawberries.


Untreated Check
Vendex
Brigade (low concentration)
Brigade (high concentration)
Pyrellin
Pyrellin + Vendex
Avid
Omite
Kelthane


Spider mites were allowed to build up in all treated plots.
Miticides were applied according to label directions. Spider
mite densities were assessed following each treatment.


Work in progress.


Response of Insect Pests to Experimental Insecticide, TD2321
J. F. Price


Location:

Objective:


Block D


To determine the'response of pest insects to 2 applications of
TD2321 applied 2 weeks apart. Response will be compared to
response to the currently available, Lannate.








Treatments:


Operation:


Summary:


Untreated check
Lannate
TD2321 40WP (low concentration)
TD2321 40WP (high concentration)
TD2321 2.5EC (low concentration)
TD2321 2.5EC (high concentration)


Spray applications were made after pest insects such as
pameras, thrips, aphids, plant bugs and other insects
appeared. Insect counts were made after each application.

Work in Progress.


Reduced Water Applications with Overhead Irrigation
Establishment of Fruiting Strawberry Plants
G. A. Clark, E. E. Albregts, and C. D. Stanley


Location:

Objective:


Block B


Determine irrigation system design and management guidelines
to reduce irrigation applications for establishing fruiting
strawberry plants with overhead irrigation systems.


Using sprinklers
Using potted vs.
days of overhead


Accomplishments:


Recommendations:


Acknowledgements:


with reduced nozzle sizes.
bare-rooted transplants with variable
irrigation.


Objective A: Reduced nozzle sizes (7/64" vs. 9/64") were
successfully used under continuous irrigation for plant
establishment with the appropriate sprinklers on a 50 ft by 50
ft triangular spacing. Application uniformity of irrigation
water was substantially reduced. However, all plant foliage
was maintained sufficiently wet for 100% establishment.
Establishment irrigation applications with reduced nozzles
(7/64") averaged 4.2 inches while standard nozzles (9/64")
applied 10.4 inches.

Objective B: Data not available at this time.

1) Use reduced nozzle sizes and limit overhead irrigation
applications when practical for plant establishment.
2) Consider limitations of existing sprinklers; reduced
nozzles may not properly drive existing impact
mechanisms. Alternative sprinklers may be necessary for
reduced nozzle sizes.
3) Minimum nozzle size should provide some overlap of
application pattern at maximum distance between
sprinklers.


This work received partial financial support
Southwest Florida Water Management District.


from the








Phosphorus


Rates for Fruiting Strawberry
E. E. Albregts


Location:

Objective:


Clones:


Block B


To evaluate the response of fruiting strawberry to P rates.


Selva on south end (Canada) and Sweet Charlie on
(AREC-Dover). Transplants were set on October 5,


Treatments:






Operation:



Summary:


north end
1992.


Phosphorus
Plot No. lbs/acre (P,25)

1 0
2 30
3 60
4 90


Phosphorus fertilizer was applied with nitrogen, potassium and
minor elements. One fourth was applied broadcast in bed and
remainder was banded in bed center 1 inch deep above drip
tube. Phosphorus soil tests were rated as high.

The zero phosphorus treatment gave numerically (but not
significantly) lower yields and fruit weight for 1991-92
season. Plant mortality from anthracnose complicated yield
results.


Plant Density for Four Strawberry Cultivars
E. E. Albregts


Location:

Objective:


Clones:


Block F


To determine effect on plant density on plant size, diseases,
and fruiting response.


Selva, Oso Grande, Seascape (Canada),
Dover). Transplanted on October 12,


Treatments:


and Sweet
1992.


Charlie (AREC-


Plant
Spacing Clone
(inches) Selva Oso Grande Seascape Sweet Charlie
------------------ Plot No. --------------

6* 1 5 9 13
9 2 6 10 14
12 3 7 11 15
15 4 8 12 16

*6 inch spacing is 2 plants/planting hole on 12 inch spacing.









Standard fertilizer, pesticide, and harvest schedules used.


Summary: Work in progress.


Canadian Grown vs Florida Grown Transplants
E. E. Albregts


Location:

Objective:


Clones:


Block F


To determine transplant source on plant growth and fruiting
response.


Sweet Charlie, Seascape, and Oso Grande.
October 13, 1992.


Treatments:


Operation:


Summary:


Transplanted on


Plant Sources Sweet Charlie Seascape Oso Grande
--------------------- Plot No.-----------------------
Canada 1 3 5
Florida 2 4 6


Local Oso Grande transplants were obtained from Ron Stalling,
local Seascape from Wallace Peacock, and Sweet Charlie from
AREC-Dover.

Work in progress.


Variety Trial
C. K. Chandler and E. E. Albregts


Location:

Objective:




Operation:


Entries:


Clone


Block C


1) To obtain unbiased comparisons between new and standard
cultivars and promising selections from the IFAS strawberry
breeding program, and 2) to determine the influence of
propagation site (northern vs. southern latitude) and planting
date on the performance of selected clones.

A select group of clones, propagated in either northern or
southern latitude nurseries or both, were planted on one or
more dates in October.

Clones are listed below in alphabetical order. Plot numbers
are in columns corresponding to the time of month in which
they were planted (either early, mid, or late October).


Source


Early


Mid


Late


Grace
Oso Grande
Seascape


Nova Scotia
Ontario
California


2,30,45
1,34,49


12,36,50


Operation:








Selva
Sweet Charlie
Sweet Charlie
FL 87-210
FL 87-236
FL 87-236
FL 90-15
FL 90-51


Ontario
Florida
Nova Scotia
Florida
Florida
Nova Scotia
Florida
Florida


Observational Trial
C. K. Chandler


Location:

Objective:


Operation:


Block C


To identify clones that tend to maintain desirable plant and
fruit characteristics throughout the season.

Ten or 20 plants each of approximately 130 clones were planted
on October 14. Ripe fruit are harvested twice weekly, and the
volume of fruit harvested is recorded. Harvested fruit are
rated for appearance, and notes are taken periodically on
clones with desirable plant habits and attractive fruit.


Row Trial
C. K. Chandler


Location:

Objective:


Block C


To provide a demonstration area to observe standard cultivars
and promising selections. This trial is also used to assess
the harvest efficiency of promising selections, and to provide
a source of fruit for postharvest studies.


Operation:


One of two rows each of 'Oso Grande', 'Selva',
'Sweet Charlie', 'Grace', and several promising
were planted in mid October. The volume of
harvested from each row is recorded.


'Seascape',
selections
ripe fruit


Seedling Trial
C. K. Chandler


Location:

Objective:

Operation:


Blocks B, C, F, and G

To select seedlings with large, attractive, and firm fruit.


One or 2 plants each of about 15,000 seedlings were
mid October. The plants are observed weekly,
showing the desired characteristics are flagged.


planted in
and those


10,25,53

6,29,51
16,21,40


8,35,48


14,27,46
18,22,43
17,33,39
7,24,37
15,28,44

5,20,38
13,26,47


9,19,42

11,32,41
4,23,52
3,31,54








Fungicide Trial
T. E. Crocker and C. K. Chandler


Location:

Objective:


Treatments:





Operation:


Block C


To test the efficacy of several formulations of Captan and 1
formulation of Phyton for control of leaf diseases and fruit
rots.

Fungicides, rate per acre, and interval
1. Unsprayed control
2. Captan 50 WP, 6 lb, 1 week
3. Captan 80 WP, 6 lb, 1 week
4. Captan 75 WG, 6 lb, 1 week
5. Phyton, 20 oz, 1 week


Cultivar: 'Oso Grande'
Planting date: 10-15-92


'Oso Grande' Spacing Trial
C. A. Sims, R. P. Bates, and C. K. Chandler


Location:

Objective:


Operation:


Block C


To examine the effects of plant spacing and fruit maturity on
color development and other quality parameters of 'Oso Grande'
strawberry.

Plants of 'Oso Grande' were set at 12, 15, and 18-inch
spacings on Oct. 17. Berries from each spacing treatment are
being taken to Gainesville and evaluated for quality.


Evaluation of Fragaria Clones for Resistance to Spider Mites
C. H. Shanks, Jr. (Washington State Univ.), C. K. Chandler,
M. van de Vrie, and J. F. Price


Location:

Objective:


Operation:


Block D


To evaluate 11 strawberry clones for resistance to spider
mites. (All but 1 of the clones have shown moderate to high
resistance when tested in Washington).


Four plots of each clone were planted in mid October.
leaf from each plant is harvested every 2 weeks and
counts are made.


One
mite








Early Planting Trial
C. K. Chandler

Location: Block B (white plastic)

Objective: To evaluate the performance of cold-stored (frigo) and plug
plants set on white plastic in late August.

Operation: Cold-stored, bareroot plants of 'Seascape' and 'Irvine' and
plug plants of 'Sweet Charlie' and FL 87-123 were planted on
August 31. Runner and fruit production is being recorded.

rP~==Pte==='ePPII=3P== el==








ACKNOWLEDGEMENT OF INDUSTRY FOR THE RESEARCH PROGRAMS
AT THE AGRICULTURAL RESEARCH AND EDUCATION CENTER,
DOVER, FLORIDA

The effectiveness of the research programs at the Agricultural Research and
Education Center here in Dover has been greatly enhanced by the excellent support
from the various segments of the Agri-business industries and producers, both
locally and nationally. This support in the form of financial grants-in-aid,
supplies, services, or equipment, supplements existing state funds and makes each
research project at the Center far more productive than could be realized
otherwise. We sincerely appreciate your participation in these research programs
and are pleased to acknowledge your support.

Listed below are the names of agencies, firms or individuals who have contributed
significantly to the research programs during the past two years. We trust that
our records are complete and say again, "Thank you for your confidence".


Chemical Dynamics, Inc.
Fermenta Plant Protection
Florida Foundation Seed Producers
Florida Strawberry Growers Association, Inc.
Kay Mukai Research Foundation
Southwest Florida Water Management District
Uni-Royal Chemical
H. Ghesquiere Farms, Inc.
Rhone
Monsanto
Hi Yield Bromine
Grace Sierra
Cedar Chemical


Plant City, FL
Albany, GA
Greenwood, FL
Plant City, FL
Watsonville, CA
Brooksville, FL
Raleigh, NC
Simcoe, Canada
Longwood, FL
St. Louis, MO
Plant City, FL
Milpitas, CA
Memphis, TN








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I-
LP


To 574


To 574
Gallagher Rd


Moore Lake Rd


To 574
& Dover


To 574


Branch Forbes Rd


AREC-
DOVER




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