• TABLE OF CONTENTS
HIDE
 Front Cover
 Field map
 Program
 Table of Contents
 Welcome and introduction
 Current list of program leader...
 Main
 Field tours
 Acknowledgement
 Map to AREC-Dover
 IFAS description






Group Title: Strawberry field day.
Title: Strawberry field day. February 2, 1995.
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Permanent Link: http://ufdc.ufl.edu/UF00076494/00010
 Material Information
Title: Strawberry field day. February 2, 1995.
Series Title: Strawberry field day.
Alternate Title: Research report - Gulf Coast Agricultural Research and Education Center ; DOV 1995-1
Physical Description: Serial
Language: English
Creator: Albregts, E. E. ( Editor )
Chandler, C. K. ( Editor )
Waters, W. E. ( Editor )
Publisher: Agricultural Research Center, Institute of Food and Agricultural Sciences
Publication Date: 1995
 Record Information
Bibliographic ID: UF00076494
Volume ID: VID00010
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
        Page 9
    Field tours
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
    Acknowledgement
        Page 25
    Map to AREC-Dover
        Page 26
    IFAS description
        Page 27
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E.E. Albregts, C.K. Chandler, and W.E. Waters, Editors


, .. UNIVERSITY OF
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Agricultural Experiment Station
Institute of Food and Agricultural Sciences


Dover GCREC Research Report DOV 1995-1















well
and
pump


Barn


Greenhouses
Greenhouses


L. Gallagher Road









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

13138 LEWIS GALLAGHER ROAD
DOVER, FL 33527-9664


STRAWBERRY FIELD DAY PROGRAM
FEBRUARY 2, 1995
Contact Person: Dr. Earl E. Albregts


MODERATOR, FIELD DAY HOST AND TOURGUIDE: Dr. Tim Crocker, IFAS
Department of Horticultural
Science


Dr. W. E. Waters, Welcome and Introductory Comments

Dr. T. E. Crocker, Safe Usage of Pesticides
Dr. E. E. Albregts, Nutrition and Culture
Dr. J. P. Gilreath, Herbicides
Dr. J. F. Price, Insect Management
Dr. C. K. Chandler, Cultivar Development
Dr. S. A. Sargent, Post-Harvest Studies
P. D. Roberts, Angular Leaf Spot
Coffee/Berry Break
Tour of Research Plots
Mite Management J. F. Price
Plant Breeding C. K. Chandler
Fungicides T. E. Crocker
Herbicides J. P. Gilreath
Culture E. E. Albregts
Disease P. D. Roberts


For individuals with disabilities requiring special accommodations, please contact Dr. Earl Albregts
at the above address.


Time, PM
2:15

2:20
2:30
2:40
2:50
3:00

3:10
3:20
3:35
3:40








TABLE OF CONTENTS


Page

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

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

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

STRAWBERRY RESEARCH ACCOMPLISHMENTS

STRAWBERRY BREEDING PROGRAM

Strawberry Breeding and Genetics Program ..................... 3

STRAWBERRY CULTURE

Effect of Nitrogen and Potassium Rates on Fruiting
Response of Strawberry ..................................... 5

Mulch Colors for Strawberry Fruiting ........................ 5

Potassium Source and Rate Study for Fruiting Strawberry ...... 5

Transplant Sources on Strawberry Fruit Production .........,... 5.

Strawberry Plant Density ................................... 6

Transplant Chilling and Planting Date ....................... 6

PLANT PATHOLOGY

Impact and Control of Angular Leaf Spot on Strawberry ........ 7

Captan Residue Study ........................................ 7

POSTHARVEST PHYSIOLOGY AND TECHNOLOGY

Physiological Responses of Strawberries to Handling
Impacts and Cooling Methods ............................... 7

Physical and Chemical Quality Characteristics of
Strawberry after Storage are Reduced by a Short Delay
to Cooling .............................................. 8

MITE MANAGEMENT

Effects of Pesticide Residues on Predator Mites .............. 8

Effect of Direct Application of Pesticides to Predator
Mites .................................................... 9








Page


Methods to Dispense Predators from Bottles ................... 9

Storage of Predators for Short Periods after Arrival ......... 9

Methods of Predator Release ................................ 9

Twospotted Spider Mite Control with Miticides ................ 9

Species of Sap Beetles in Dover Area Strawberries ............ 9









POST HARVEST STUDIES
Page

FIELD TOUR

Tray Plants in the Fruit Production Field E. E. Albregts ........ 11

Fertilizer Source and Rate Study on Microirrigated
Strawberry E. E. Albregts ............................... 12

Solarization and Nematicide Study E. E. Albregts, J. P. Gilreath,
and C. K. Chandler .......................................... 13

Captan Residue Study T. E. Crocker ............................ 14

Evaluation of Herbicides for Use Under Polyethylene Mulch in
Strawberries W. M. Stall and J. P. Gilreath ............... 15

Seedling Trial C. K. Chandler ................................. 16

Variety Trial C. K. Chandler and E. E. Albregts ................. 16

Fungicide Trial T. E. Crocker, D. E. Legard, A. J. Whidden, and
C. K. Chandler .......................................... 17

Observational Trial C. K. Chandler and J. C. Sumler, Jr. ........ 17

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

Transplant Quality Trial E. B. Bish, C. K. Chandler, and
D. J. Cantliffe ........................................ 18

Epidemiology and Control of Xanthomonas fragariae P. D. Roberts
and J. B. Jones .......................................... 19

Evaluation of Effectiveness of Chemical Pretreatment for
Reduction of Angular Leaf Spot Disease P. D. Roberts and
J. B. Jones ........................................... 20

Evaluation of Four Strawberry Cultivars for Resistance to
Xanthomonas fragariae and Phomopsis obscurans P. D. Roberts
and J. B. Jones ........................................ .. 21

Effects of AC303-630 Miticide on Predator Mites J. F. Price ..... 22

Effects of Experimental Miticides on Twospotted Spider Mites -
J. F. Price ............................................ 22

Demonstration of Biological Control of Twospotted Spider Mite -
J. F. Price ........................................... 23








Page


Population Dynamics of Sap Beetles Affecting Strawberries -
Mark Potter and J. F. Price ............................... 23

Reproduction of Sap Beetles on Strawberries in Row Middles -
Mark Potter and J. F. Price ............................... 24

Acknowledgements ............................................. 25









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 Gulf Coast 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 unit and the 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 participate in strawberry
research 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 the Center 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. We welcome input
concerning industry needs to keep our research and extension programs
productive.









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


Albregts, Earl E.


Chandler, Craig K.



Gilreath, James P.


Jones, Jeffrey B.


Legard, Daniel E.


Price, James F.


Waters, Will E.


1967. Soil Scientist. Soil and plant nutrition
and culture of strawberry and vegetable crops,
GCREC-Dover.
1987. Associate Geneticist and Plant Breeder.
Local administration, genetics, plant breeding,
and development of strawberry cultivars, GCREC-
Dover.

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

1981. Bacteriologist. Ecology and control of
bacterial diseases of ornamental, vegetable and
strawberry crops, GCREC-Bradenton.

1995. Assistant Plant Pathologist. Etiology and
control of strawberry and vegetable diseases,
GCREC-Dover.

1978. Associate Entomologist. Identification,
biology and control of insect and mite of
ornamental and strawberry crops, GCREC-Bradenton.

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


UNIVERSITY SUPPORT PERSONNEL SYSTEM STAFF


Annie F. Turgeau
Alicia J. Whidden
James C. Sumler, Jr.
Kelly Burke
Larry J. Smith
Frederick D. Wenzel
Mitchel Boles


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








STRAWBERRY BREEDING AND GENETICS PROGRAM


C. K. CHANDLER
1992-93. IFAS's new strawberry cultivar Sweet Charlie generally performed
well during its first season in commercial production, and had high
consumer acceptance -- especially for roadside markets in the west
central Florida area. Sweet Charlie fills an important niche in the
market by providing a consistent supply of fruit between the
production peaks of the Selva and Oso Grande cultivars.

Cultural research conducted to determine the best production
practices for exploiting the full genetic potential of new cultivars
and advanced selections has led to the following recommendations for
growing Sweet Charlie:

1. Plant during the first half of October for the highest total
yield.

2. Keep soil nitrogen low (1/4-1/2 lb N/acre/day).

3. Harvest every 2-3 days if daytime temperatures are in the 80s
and night temperatures are in the 60s. (Sweet Charlie berries
mature from the pink to red stage quicker than Oso Grande
berries.)

4. Harvest early in the morning, if possible (i.e., harvest
Sweet Charlie first, then Oso Grande and Selva).

5. Reduce the incidence of Botrytis infection by applying Captan,
Thiram, Benlate, Topsin-M, or Rovral to flowers and developing
fruit. Using Captan or Thiram in combination with one of the
benzimidazole compounds (Benlate or Topsin-M) or with Rovral
may help to delay the occurrence of fungicide-resistant fungi.

Sweet Charlie is the beginning of what we hope will be a steady
stream of improved University of Florida strawberry cultivars. Our
immediate goal is to find suitable replacements for the California
cultivars Selva and Oso Grande, which now provide the bulk of the
fruit during the very early and late portion of the Florida season
respectively. Our long-term goal is to produce additional clones
with desirable plant habits, fruiting patterns, fruit quality, and
pest resistance. To achieve these goals we are conducting an active
program of recurrent selection. During the 1992-93 season this
program included 1) making crosses among 46 clones to combine
desirable traits, 2) selecting desirable families and individual
genotypes from among a population of approximately 15,000 seedlings,
and 3) determining which of 130 selections in the stage 2 trial
should be saved for further evaluation or use as parents.

1993-94. Approximately 12,000 seedlings were evaluated in fruiting field
trials during the 1993-94 season. Several hundred of these
seedlings were selected for future trials. One cross, FL 90-15 x FL








90-38, produced a relatively high percentage (27 out of 207) of
seedlings that were selected because of their exceptionally
attractive fruit.

In an observational trial containing one 10-plant plot per
selection, FL 90-10 produced high early yields; FL 90-20 produced
noticeably attractive fruit; FL 91-8 produced steady yields of good
quality fruit; and FL 91-54 was rated above average for most traits.

In a replicate trial, FL 87-236 produced the highest total fruit
yield. This selection has the ability to produce large fruit on
small plants. FL 90-51 had lower yields, but generally better fruit
quality than FL 87-236. FL 90-15, which is currently the most
promising of the advanced selections, had a fruiting pattern, total
yield, and average fruit size similar to Sweet Charlie, but its
fruit tended to have better firmness and shape than the fruit of
Sweet Charlie, and it had very few fruit that were split or
deformed. FL 90-15 will be looked at closely during the 1994-95
season, and a decision to recommend or not recommend this clone for
release consideration will probably be made sometime during the
spring of 1995.

The 3 main strawberry cultivars being grown commercially in west
central Florida, Selva, Sweet Charlie, and Oso Grande, were
evaluated for fruit yield and quality. November-December yields for
Selva and Sweet Charlie were similar, while Oso Grande yields were
considerably lower for this period. Sweet Charlie produced the
highest number of flats per acre in February (1,396) and for the
season (3,534). The February yield for Selva was 506 flats per
acre, followed by Oso Grande with 453 flats per acre. Totals for
the season were 3,001 flats per acre for Selva and 2,885 flats per
acre for Oso Grande. Sweet Charlie received the highest ratings for
color uniformity, followed by Selva. Oso Grande had the poorest
color uniformity of the 3 cultivars. Sweet Charlie also received
the highest ratings for flavor intensity and sweetness, followed by
Oso Grande. Selva received the lowest flavor intensity and
sweetness ratings. Selva received the highest firmness ratings,
followed by Oso Grande. Sweet Charlie was significantly softer than
the other 2 cultivars.









STRAWBERRY CULTURE


E. E. ALBREGTS
Effect of Nitrogen and Potassium Rates on Fruiting Response of Strawberry.
Separate potassium and nitrogen fertilizer rate studies were
conducted during two seasons. Rates of nitrogen in the nitrogen
study and potassium in the potassium study were 0.25, 0.50, 0.75,
1.00, and 1.25 Ibs/acre/day. Potassium chloride was used as the K
source and ammonium nitrate-urea as the N source. The K rate for
the N trial and the N rate for the K trial was 0.75 Ibs/acre/day.
Marketable fruit yields during both seasons were not significantly
different because of K rates. Average fruit weight may decrease
with increased K rates of some varieties ('Oso Grande' and 'Sweet
Charlie'). Nitrogen rates of 0.50 to 0.75 Ibs/acre/day were
sufficient for maximum fruit yield and quality.

Mulch Colors for Strawberry Fruiting. Eight colors of polyethylene mulch
were evaluated in the strawberry fruit production field during 4
seasons. These were yellow, red, silver, black, green, blue, brown,
and orange. Fruit yield by March 1 was greater with the yellow and
white mulch treatments than the black mulch treatments during all
seasons. Average fruit weight and percent marketable fruit with the
yellow and white mulches were higher or the same as the other mulch
colors. The yellow and white mulched beds were cooler than the
black mulched beds.

Potassium Source and Rate Study for Fruiting Strawberry. 'Sweet Charlie'
and 'Oso Grande' were grown in a winter fruit production study using
potassium chloride (KC1), potassium nitrate (KNO,), and potassium
hydroxide (KOH), at rates of 0.00, 0.25, 0,50, and 0.75 Ibs/acre/day
of potassium through the drip irrigation system. Nitrogen was
applied to all plots at 0.75 Ibs/acre/day. Regardless of the
potassium source, a K rate between 0.5 to 0.6 Ibs/acre/day gave
highest marketable fruit yields. With both strawberry cultivars,
the average fruit weight decreased with increasing potassium rate.
Potassium hydroxide gave the least reduction of the average fruit
weight with increasing potassium rate. The zero potassium rate did
not effect fruit yield of 'Sweet Charlie' in November and December
but it did decrease yields the remainder of the season. The fruit
yield of 'Oso Grande' was reduced all season by the zero potassium
rate. Potassium source had little effect on petiole sap potassium
concentrations until late March when potassium hydroxide gave higher
K reading than the other 2 sources. Potassium hydroxide gave
highest potassium leaf concentrations on the March sampling date.
The soil potassium level before fertilization was 46 ppm (medium
level) by the Mehlich-1 methodology.

Transplant Sources on Strawberry Fruit Production. 'Sweet Charlie', 'Oso
Grande', and 'Seascape' strawberry transplants were obtained from
nurseries in Florida and southern Canada and set into fruit
production plots in October during 2 seasons. Canadian grown
transplants were the first to begin fruit production and had higher
yields than Florida grown transplants during December each season.








During the first season 'Sweet Charlie' transplants from Canada gave
greater seasonal yields than 'Sweet Charlie' transplants from
Florida, yet Florida 'Seascape' transplants outyielded Canadian
grown transplants. Fruit from Florida grown transplants generally
had higher average fruit weight. Transplant source did not
significantly affect cull fruit yield or percent marketable fruit.
Data indicate that yield and cash return differences due to plant
source can be expected to vary with the season.

Strawberry Plant Density. A two year study using 'Selva', 'Seascape',
'Oso Grande', and 'Sweet Charlie' cultivars was recently completed.
Four plant density treatments were used. One was the use of
planting holes 12 inches apart with two plants per planting hole.
The remaining plant spacings were 9, 12, and 15 inches with one
plant per planting hole. Plants per acre for the 6, 9, 12, and 15
inch spacing treatments were 44,000, 33,000, 22,000, and 11,000,
respectively. The usual two plant rows per bed with bed tops of 2
feet and the standard practices of mulch and fumigated beds with
overhead irrigation were used. The fruit yields through January
were generally highest with the most dense plantings. The 15 inch
plant spacing gave the lowest fruit yields through January during
both seasons. Although not significant, the highest seasonal fruit
yields during both seasons for 'Oso Grande' plants were with the 12
inch spacing. Highest seasonal yields for 'Sweet Charlie' during
both seasons were with the two most dense plant treatments. The
more dense the planting the greater the amount of cull fruit during
both seasons. The average fruit weight varied little during either
season because of plant density. However, increased plant density
increased runner production. Keep in mind that increased fruit
production with greater plant density does not necessarily mean
increased profit. Production costs are also greater with increased
plant density.

Transplant Chilling and Planting Date. During two seasons, runner tips of
two or four clones of strawberry were placed in trays on 3 dates and
established. With plants remaining in trays, plants were given 0,
2, and sometimes 4 weeks of chilling. The chilling treatments
consisted of placing the plant trays in an unlighted cooler at 330f
for 16 hours and outside in the sun for 8 hours daily. Plants were
set in the fruiting field in 1992 on 21 Sept., and 05 and 19 Oct.
and in 1993 on 02 Aug., and 03 and 28 Sept.

During the first season, 'Seascape' fruit yields through January
were reduced with 2 weeks of plant chilling on the first planting
date and with 4 weeks of chilling on the second planting date.
Chilling of 'Sweet Charlie' plants had little effect on early yield.
On the last planting date, chilling reduced the seasonal yield of
both clones. Average fruit weight of 'Sweet Charlie' increased with
later planting. The percent marketable fruit on the second planting
date was reduced with 'Seascape' and increased with 'Sweet Charlie'
with increased chilling.

During the second season, chilling had no effect on fruit yield and
quality with the last planting date giving the best response.








PLANT PATHOLOGY


PAMELA D. ROBERTS, RICHARD D. BERGER, JEFFREY B. JONES,
AND CRAIG K. CHANDLER

Impact and Control of Angular Leaf Spot on Strawberry. Experiments were
conducted in 1993-94 on angular leaf spot, caused by the bacterium
Xanthomonas fragariae, to determine if this disease causes a yield
loss and to investigate possible control measures. Disease severity
reached @25% in field plots of 'Sweet Charlie' thirteen weeks after
plants had been inoculated with the bacterium. Yield was reduced an
average of 12% compared to healthy plants. Sprays of a full rate of
Kocide 101 plus Dithane Df applied at 7-14 day intervals reduced
disease severity, but this chemical level was phytotoxic and both
plant size and yield was reduced. Sprays at 10% of the above
combination applied at 4-7 day intervals were not phytotoxic, but
this low rate did not provide noticeable control of the disease.
The spread of bacteria from the plants inoculated with the bacterium
was minimal; thus, yield losses due to angular leaf spot could be
avoided by beginning the season with disease-free plants.



CAPTAIN RESIDUE STUDY

T. E. CROCKER
Captan Residue Study. Conducted 2 Captan residue studies on fruiting
strawberry and with the use of overhead sprinkler irrigation.
Residue samples were taken and the data were submitted to the EPA
through the IR-4 program to re-write the 24-C label for Captan on
fruiting strawberry.


POSTHARVEST PHYSIOLOGY AND TECHNOLOGY

STEVEN A. SARGENT
Physiological Responses of Strawberries to Handling Impacts and Cooling
Methods. Studies were undertaken to determine the feasibility of
improving strawberry handling and cooling efficiency while extending
shipping life. This project was the M.S. thesis research of M. D.
Ferreira and in cooperation with J. K. Brecht (Horticultural
Sciences Department), J. A. Bartz (Plant Pathology Department), and
C. K. Chandler (GCREC-Dover). Strawberries were found to be more
easily bruised by compression force than by impact force. These two
types of forces also had opposite effects depending on the pulp
temperature at time of testing (either 34F (1C) or 75F (24C). When
held at the lower temperature, strawberries were more bruise-
resistant to compression and when at ambient temperature, fruits








were more resistant to impacts. These effects of temperature on
bruise resistance favor strawberry handling at ambient temperatures
and shipping under refrigeration.

Hydrocooled strawberries did not have reduced shipping life when
directly compared to those which were forced-air cooled. On the
contrary, after cooling and two weeks storage at 34F (1C) or 45F
(7C), hydrocooled fruits had less weight loss (and in some cases a
weight gain) and were firmer than those which were forced-air
cooled. Strawberries which were hydrocooled, overwrapped with PVC
film and stored at 34F (1C) showed better color quality after
storage than force-air cooled. Incidence and severity of decay were
similar for both cooling methods unless the strawberries were
previously bruised; in this latter case hydrocooled fruits had more
decay. Two principal postharvest pathogens, Rhizopus stolonifer and
Botrytis cinerea, were effectively controlled by maintaining free
chlorine at 120 ppm and pH of 6 to 7 in the hydrocooling water.
Chlorine was more effective in controlling decay at ambient or
elevated temperatures (75F and 104F; 24C and 40C) than at low
temperatures (36F or 41F; 2C or 5C).

With these promising results, we plan to determine the feasibility
of implementing value-added strawberry packs through grading,
cooling and packing at a central facility. Further studies are
necessary to determine procedures and equipment capable of handling
strawberries with minimal injury.

Physical and Chemical Quality Characteristics of Strawberries after
Storage are Reduced by a Short Delay to Cooling. This project is a
part of the Ph.D. research of M.C.N. Nunes, in collaboration with J.
K. Brecht (Horticultural Sciences Department), and A.M.M.B. Morais
(Escola Superior de Biotecnologia, Porto, Portugal). A 6-hr delay
in forced-air cooling of strawberries caused 50% more water loss
than immediate cooling after harvest, following evaluation after 7
days storage at 34F (1C) plus 1 day at 68F (20C). Delayed-cooled
fruits were also softer, had less bright color and had significant
losses in ascorbic acid and soluble solids content after storage.


MITE MANAGEMENT

J. F. PRICE, M. VAN DE VRIE, AND MARK POTTER
Effects of Pesticide Residues on Predator Mites. Residues of methomyl
remained highly toxic to the Phytoseiulus persimilis predator after
8 days. Propargite (Omite), diazinon, abamectin (Agri-Mek),
mevinphos (Phosdrin) and malathion residues caused less than 25%
predator mortality after 1, 2,2,3, and 6 days respectively. One-
day-old residues of spray oil, azadirachtin (neem seed extract),
fenbutatin oxide (Vendex), sulfur, captain, bicarbonate of soda, and
insecticidal soap were not hazardous to the predator.








Effect of Direct Application of Pesticides to Predator Mites. When
pesticides were applied after predators were present in the field,
there were significant predator reductions in plots treated with
abamectin (Agri-Mek), malathion, methomyl (Lannate), and mevinphos
(Phosdrin) two days after application; there were greater predator
population reductions in plots treated with abamectin and permethrin
(Ambush). Abamectin eliminated the predator's food which in turn
reduced predators.
Methods to Dispense Predators from Bottles. When P. persimilis were
released from shipping containers into strawberry fields, fewest
remained in shipping containers at the conclusion of the release
operations when the predators were chilled and when container
contents were agitated every 3 minutes. Mechanical dispensing
results in a more consistently even dose than does manual
dispensing.
Storage of Predators for Short Periods after Arrival. Newly harvested
predators held in coolers at the farm site lost vigor after 5 days
but egg laying was not affected.

Methods of Predator Release. Predators on commercial strawberry farms
were more effective when dispersed sparsely and early over the
entire crop than when released later at high densities at sites of
spider mite outbreaks.
Twospotted Spider Mite Control with Miticides. Bifenthrin (Brigade)
resulted in rapid reduction but was less effective after multiple
applications. Applications of abamectin (Agri-Mek) and propargite
(Omite) were effective throughout the season. Dicofol (Kelthane)
and alanycarb did not provide satisfactory control.

Species of Sap Beetles in Dover Area Strawberries. Nine species of
Nitidulidae (sap beetles) were found to attack ripe strawberry fruit
in Hillsborough Co. Florida. Different species were predominant
early, mid and late season.



















FIELD TOURS









TRAY PLANTS IN THE FRUIT PRODUCTION FIELD


E. E. ALBREGTS


Location:

Objective:


Clones:


Block G


To determine the fruiting response of runner tip tray
plants set on 5 planting dates.

'Sweet Charlie', 'Oso Grande', 'Selva', 'Seascape', N-
27, and N-29. Runner tips were from Nourse nursery and
GCREC-Dover.


Treatments:


Operation:




Summary:


Plot
No.
1
2
3
4
5


Date Set
in Trays
7/7/94
7/20/94
8/4/94
8/18/94
9/2/94


Date Set
in Field Plots
9/6/94
9/19/94
10/3/94
10/17/94
11/1/94


Nourse plants of 'Seascape', 'Sweet Charlie', and 'Oso
Grande' were set on all 5 planting dates. Nourse
'Selva' plants were set on 9/19 and 10/3/94. GCREC-
Dover 'Oso Grande' and 'Sweet Charlie' were set on all.
planting dates.


Work in progress.


------


--










FERTILIZER SOURCE AND RATE STUDY ON
MICROIRRIGATED STRAWBERRY

E. E. ALBREGTS


Location:

Objective:


Cultivars:


Block A


To compare the fruiting response of strawberry to
various granular slow release fertilizers and to
fertilizer applied through drip irrigation system.

'Sweet Charlie' south end and 'Oso Grande' north end
of each plot. Transplanted on October 13, 1994.


Treatments:











Operation:




Summary:


Plot
No.


Dry Fertilizer
Source


Fertilizer
Rate N-lbs/acre


1 15-5-15 102
2 15-5-15 135
3 15-5-15 167
4 18-0-0 130
5 18-0-0 160
6 18-0-0 190
7 75% (18-0-0)+25% (40-0-0) 130
8 75% (18-0-0)+25% (40-0-0) 160
9 75% (18-0-0)+25% (40-0-0) 190
10 Liquid 8-0-7 1/2 Ib/acre/day

Treatments 4 through 9 received the same amount of
phosphorus and potassium as treatment 3. Treatment 10
received a total of 1/2 Ib/acre/day of potassium. All
granular fertilizer was applied above the drip tube
one inch below soil surface.

Work in progress.









SOLARIZATION AND NEMATICIDE STUDY


E. E. ALBREGTS, J. P. GILREATH, AND C. K. CHANDLER


Location:

Objective:


Cultivars:


Treatments:


Block B


To evaluate alternatives to methyl bromide for
strawberry fruit production.

'Sweet Charlie' south end and 'Oso Grande' north end
of each plot. Transplanted on October 17, 1994.


Plot
No.


Solarization


Fumigation


Fumigation
Date


Mulch
Color


None
1/2 MC-2
1/2 CKa
1 CKa
1/2 Teloneb
1/2 Vapamc
None
1/2 MCd2d
1 MC-2
1 Teloneb
1 Vapamc


aHalf and full rates
and 36 tons/acre
bHalf and full rates
CHalf and full rates
dHalf and full rates
and 400 Ibs/acre


Operation:




Summary:


of chicken manure (CK) were 18

of telone were 20 and 40 gal/acre
of vapam were 50 and 100 gal/acre
of Methyl Bromide 98-2 were 200


Solarization began on 7/6/94 and ended on 10/14/94
when clear mulch was painted black. Plants were
established with overhead irrigation. After
establishment, water and fertilizer were applied
through drip irrigation system.

Soil temperatures (from 7/6/94 to 10/14/94) under the
clear mulch at the 6 and 12 inch soil depth varied
from 84 to 1200F.


Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No


7/6/94
7/6/94
7/6/94
7/6/94
7/6/94
7/6/94
10/7/94
10/7/94
10/7/94
10/7/94
10/7/94


Clear
Clear
Clear
Clear
Clear
Clear
Black
Black
Black
Black
Black









CAPTAIN RESIDUE STUDY


T. E. CROCKER


Location:

Objective:

Cultivars:

Treatments:










Operation:



Summary:


Blocks D and G

To obtain data for Captan 24-C label for drip
irrigated strawberry.
'Sweet Charlie' and 'Oso Grande'

Plot No.

1 'Oso Grande' plants receiving Captan at 3
Ibs a.i./acre applied once weekly.

2 'Sweet Charlie' plants receiving Captan at
3 Ibs a.i./acre applied once weekly.

Plants receive drip irrigation except
during plant establishment and freezes.


Fruit samples will be taken for residue analyses.
Residue analysis data will be sent to EPA through the
IR-4 program to rewrite the 24-C label for drip
irrigated strawberry.

Work in progress.









EVALUATION OF HERBICIDES FOR USE UNDER POLYETHYLENE
MULCH IN STRAWBERRIES

W. M. STALL AND J. P. GILREATH


Location:

Objective:







Treatments:


Block G


Loss of methyl bromide as a soil fumigant probably
will necessitate development of a combination fumigant
and herbicide program to control weeds, soil borne
diseases and nematodes in strawberry. Research is
being conducted at Dover, Gainesville, and Live Oak to
identify preemergence herbicides which can be used
safely and effectively when applied under polyethylene
mulch film in strawberry as part of this program.


Plot No


lb. a.i./A


Nontreated check
Princep
Goal
Goal
Stinger
Dual
Surflan
Barricade
Prowl
Devrinol
Treflan (ppi)
Eptam (ppi)
Sinbar
Sinbar
Zorial (ppi)
Zorial (ppi)


Operation:






Summary:


Herbicides were applied to the bed surface and beds
were covered with mulch film within 1 hour. Treflan,
Eptam, and Zorial were mixed into the top inch of soil
with a rake prior to mulch application. Weed control
and crop response are being assessed at intervals
throughout the season. Fruit production is being
recorded.

Work in progress.


1.0
0.5
0.25
0.187
1.5
2.0
0.33
0.75
4.0
0.75
3.0
6 oz.
4 oz.
0.5
1.0









SEEDLING TRIAL

C. K. CHANDLER


Location:

Objective:


Operation:


Blocks B, C, D, and F

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

One or 2 plants each of about 12,000 seedlings were
planted in early November. The plants are observed
weekly, and those showing the desired characteristics
are flagged.


VARIETY TRIAL

C. K. CHANDLER AND E. E. ALBREGTS


Location:

Objective:


Block C


To obtain unbiased comparisons between
and promising selections from the IFAS
breeding program.


Sweet Charlie
strawberry


Operation:





Entries:


Runner tips of Sweet Charlie were collected on July 4
and August 26, and six numbered selections were
collected on August 26. The tips were rooted in 2 x 2
inch cell trays to produce plug plants. These locally
propagated plug plants were planted on October 12.


Clone


Plot
Numbers


Cl one


Plot
Numbers


Sweet Charlie
"young" (tips
collected 8/26)

Sweet Charlie
"old" (tips
collected 7/4)


FL 90-10


8,15,23


3,16,18


5,13,21


FL 90-15 2,9,20

FL 90-20 6,11,19


FL 91-8


7,14,22


FL 91-33 4,12,24

FL 91-54 1,10,17


VC~l one....








FUNGICIDE TRIAL

T. E. CROCKER, D. E. LEGARD, A. J. HIDDEN,
AND C. K. CHANDLER


Location:

Objective:

Treatments:


Operation:


Block C


To test the efficacy of several fungicide formulations
for control of fruit rots.

Fungicides, rate per acre, and interval

1. Untreated control
2. Rovral 50 WP, 2 lb, 3 applications (1 on Dec. 9
and 2 in late Jan.)
3. Rovral 4 SC, 1 qt, same as treatment 2
4. RP EXP370 50 WG, 2 lb, same as treatment 2
5. RP EXP566 2 SC, 2 qt, same as treatment 2
6. Aliette 80 WG, 3.75 lb, applications every 7
days starting in early Dec.
7. Aliette 80 WG, 5.00 lb, same as treatment 6
8. Ridomil 2 EC, 2 qt, same as treatment 6

1. Cultivar: Oso Grande
2. Planting date: 10-18-94
3. All plots were sprayed with Rovral 50 WP (2
Ib/acre rate) on Dec. 2, and with Captan or
Thiram every 7 days starting in early Nov.


OBSERVATIONAL TRIAL

C. K. CHANDLER AND J. C. SUMLER, JR.


Location:

Objective:

Operation:


Block C


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

Ten plants each of 169 clones were planted on October
17. 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:




Operation:


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.

One or two rows each of Selva, Oso Grande, Sweet
Charlie, Camarosa, Cuesta, Carlsbad, Laguna, Levin,
Lincoln and several promising selections were planted
on October 17 and 18. The volume of ripe fruit
harvested from each row is recorded.


TRANSPLANT QUALITY TRIAL

E. B. BISH, C. K. CHANDLER, AND D. J. CANTLIFFE


Location:

Objective:

Treatments:















Operation:


Block C


To evaluate the performance of different types of
transplants.

1. 1st (vegetative) generation (from micro-
propagated plantlets) plugs, #1 grade
2. 1st generation plugs, #2 grade
3. 1st generation plugs, #3 grade
4. Ist generation bareroot, #1 grade
5. 1st generation bareroot, #2 grade
6. 2nd generation bareroot, #1 grade (Oso Grande
only)
7. 2nd generation bareroot, #2 grade
8. 2nd generation, field propagated plugs (S.
Charlie only)
9. 3rd generation, field propagated plugs (S.
Charlie only)
10. 3rd generation, greenhouse propagated plugs (S.
Charlie only)
11. Field propagated plugs (not descended from
micropropagated plantlets) (S. Charlie only)


Cultivars: Oso Grande and Sweet Charlie
Planting date: 10-4-94









EPIDEMIOLOGY AND CONTROL OF XANTHOMONAS FRAGARIAE

P. D. ROBERTS AND J. B. JONES

Location: Block D

Objective: Determine the economic impact of Xanthomonas fragariae
on strawberry production in Florida. Evaluate methods
of control using chemicals.

Plot
Treatments: No.

1 'Sweet Charlie' no chemical sprays.
2 'Sweet Charlie' 10% mixture of Kocide 101 and
Dithane DF applied at 3-4 day intervals.
3 'Sweet Charlie' Full rate of Kocide 101 and
Dithane DF applied weekly.
4 'Sweet Charlie' 10% Kocide 101 applied at 3-4
day intervals.
5 'Sweet Charlie' inoculated with Xanthomonas
fragariae no chemical sprays.
6 'Sweet Charlie' inoculated with Xanthomonas
fragariae 10% mixture of Kocide 101 and
Dithane DF applied at 3-4 day intervals.
7 'Sweet Charlie' inoculated with Xanthomonas
fragariae Full rate of Kocide 101 and Dithane
DF applied weekly.
8 'Sweet Charlie' inoculated with Xanthomonas
fragariae 10% Kocide 101 applied at 3-4 day
intervals.

Summary: Work in progress.








EVALUATION OF EFFECTIVENESS OF CHEMICAL PRETREATMENT
FOR REDUCTION OF ANGULAR LEAF SPOT DISEASE

P. D. ROBERTS AND J. B. JONES


Location:

Objective:




Treatments:










Summary:


Block D


Evaluate various chemicals used as a preplanting
treatment on strawberry plants infected with
Xanthomonas fragariae in attempt to reduce initial
disease inoculum and spread.

Plot
No.

1 'Oso Grande' plants dipped in water prior to
planting.
2 'Oso Grande' plants dipped in a solution of
bleach prior to planting.
3 'Oso Grande' plants dipped in 100 ppm solution
of Kocide 101.
4 'Oso Grande' plants dipped in 100 ppm solution
of oxytetracycline.


Work in progress.








EVALUATION OF FOUR STRAWBERRY CULTIVARS FOR
RESISTANCE TO XANTHOMONAS FRAGARIAE AND PHOMOPSIS OBSCURANS.

P. D. ROBERTS AND J. B. JONES

Location: Block D

Objective: Determine the relative susceptibility of various
strawberry cultivars in the field to Xanthomonas
fragariae and Phomopsis obscurans.

Plot
Treatments: No.

1 'Oso Grande' inoculated with Xanthomonas
fragariae.
2 'Sweet Charlie' inoculated with Xanthomonas
fragariae.
3 '90-15' inoculated with Xanthomonas fragariae.
4 '90-51' inoculated with Xanthomonas fragariae.
5 'FL-236' inoculated with Xanthomonas fragariae.
6 'Camarosa' inoculated with Xanthomonas
fragariae.
7 'Oso Grande' inoculated with Phomopsis
obscurans.
8 'Sweet Charlie' inoculated with Phomopsis
obscurans.
9 '90-15' inoculated with Phomopsis obscurans.
10 '90-51' inoculated with Phomopsis obscurans.
11 'FL-236' inoculated with Phomopsis obscurans.
12 'Camarosa' inoculated with Phomopsis obscurans.

Summary: Work in progress.









EFFECTS OF AC303-630 MITICIDE ON PREDATOR MITES


JAMES F. PRICE


Location:

Objective:







Operation:



Summary:


Block E


Miticides can be useful to reduce twospotted spider
mite populations before releasing predators for spider
mite control and to reduce high populations of spider
mites after predators have been released, but before
control has been achieved. This experiment is
designed to determine if AC303-630 miticide is
compatible with the use of P. persimilis predators for
spider mite control in strawberries.

Spider mites and predators have been released in
replicated plots. AC303-630 will be applied to some
plots while other plots will not be treated. Predator
populations under both conditions will be monitored.

Work in progress.


EFFECTS OF EXPERIMENTAL MITICIDES ON TWOSPOTTED SPIDER MITES

JAMES F. PRICE


Location:

Objective:




Operation:





Summary:


Block E


A few new miticides are in the advanced stages of
development and may be useful to Florida strawberry
producers. This study is designed to determine the
usefulness of three new miticides to strawberry
production in Florida.

Strawberry plants were inoculated artificially with
twospotted spider mites. Three new miticides,
fluazinam, CM-006 (an avermectin-like compound), and
AC303-630 will be applied in replicated plots.
Comparisons of spider mites populations will be made
to replicated plots left untreated.

Work in progress.














Location:

Objective:






Operation:






Summary:


DEMONSTRATION OF BIOLOGICAL CONTROL OF
TWOSPOTTED SPIDER MITE

JAMES F. PRICE

Entire GCREC Dover acreage

The strawberry acreage at the Dover GCREC is complex
relative to spider mite infestations. Plants are set
over a 3 month period from stock produced out of state
with few to many spider mites. The purpose of this
demonstration is to establish effective biological
control over the entire farm from a single release of
predator mites.

Predator mites were released over the entire farm at
the average density of one predator mite per
strawberry plant. Two areas planted to early set,
mite-infested transplants, are being treated weekly
with Vendex as an adjunct to biological control.
Treatments will cease as predators gain control of
spider mites.

Work in progress.


POPULATION DYNAMICS OF SAP BEETLES AFFECTING STRAWBERRIES

MARK POTTER AND JAMES F. PRICE


Location:

Objective:


Operation:





Summary:


Block E and on farms of cooperating producers

To determine the species and seasonal population
densities of the sap beetles that burrow into ripe
strawberry fruit.

Baited pitfall traps have been placed among
strawberries at the GCREC Dover and at seven
commercial farms. Traps are examined weekly for sap
beetles that have been infesting the fields. The
species that occur and their densities throughout the
season are being monitored.

Work in progress.









REPRODUCTION OF SAP BEETLES ON STRAWBERRIES IN ROW MIDDLES


MARK POTTER AND JAMES F. PRICE


Location:

Objectives:







Operation:



Summary:


Block E


Fruit infested with sap beetles on the plant bed are
conducive to the reproduction of sap beetles that can
further attack fruit. Current recommendations provide
for farmers to pick infested fruit and deposit them in
row middles if economics prohibit removal from the
field. The purpose of this study is to determine if
major species of sap beetles can reproduce in fruit
left to deteriorate in row middles.

Ripe fruit are infested with adult sap beetles and are
left to develop on plant beds and in row middles.
Progress of sap beetle development is monitored under
both conditions.

Work in progress.








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

The effectiveness of the research programs at the Gulf Coast 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".


Bridges Equipment, Inc.
BBI Produce, Inc.
Florida Strawberry Festival
G. W. Allen Nursery
Sierra-Cascade Nursery
Micro Flo Company
Zeneca Ag. Products
Chemical Dynamics, Inc.
Florida Foundation Seed Producers
Florida Strawberry Growers Association, Inc.
Kay Mukai Research Foundation
Rhone-Poulenc Ag. Company
Hi Yield Bromine
Cedar Chemical
Helena Chemical Co.
Chemical Containers, Inc.
Williamson Berry Farms, Inc.
Hollis Maxwell
Tampa Farm Service
Carl Pippin & Sons
Paradise Fruit Company
Norcal Nursery
Lassen Canyon Nursery
Holmberg Farms, Inc.
American Cyanamid
Bunting Biological N.A.
Brock Farms
ICI Americas
Koppert B.U.
Williford Farms
Jones Farms
Dow Elanco


Brandon, FL
Dover, FL
Plant City, FL
Centerville, NS
Susanville, CA
Lakeland, FL
Wilmington, DE
Plant City, FL
Greenwood, FL
Plant City, FL
Watsonville, CA
Longwood, FL
Plant City, FL
Memphis, TN
Tampa, FL
Lake Wales, FL
Dover, FL
Dover, FL
Dover, FL
Plant City, FL
Plant City, FL
Red Bluff, CA
Redding, CA
Lithia, FL
Princeton, NJ
Oxnard, CA
Plant City, FL
Wilmington, DE
The Netherlands
Ruskin, FL
Dover, FL
Tampa, FL











1-75


To 574
Mclntosh Rd.



To 574
Gallagher Rd. GCREC-
Dover





/' Moore Lake Rd.

To 574
and Dover
















IFAS IS:


0 The Institute of Food and Agricultural Sciences,
University of Florida.
O A statewide organization dedicated to teaching,
research and extension.
I Faculty located in Gainesville and at 13 research
and education centers, 67 county extension
offices and four demonstration units throughout
the state.
O A partnership in food and agriculture, and natural
and renewable resource research and education,
funded by state, federal and local government,
and by gifts and grants from individuals, founda-
tions, government and industry.
O An organization whose mission is:
Educating students in the food, agricultural,
and related sciences and natural resources.
-Strengthening Florida's diverse food and
agricultural industry and its environment
through research.
Enhancing for all Floridians, the application of
research and knowledge to improve the quality
of life statewide through IFAS extension
programs.















Gulf Coast Research and Education Center Dover
13138 Lewis Gallagher Road
Dover, FL 33527






All programs and related activities sponsored for, or assisted by, the Florida Agricultural Experiment Station are open to all persons regardless of race, color, age, sex, handicap or national
origin. Information from this publication is available in alternate formats. Contact the Educational Media and Services Unit, University of Florida, PO Box 110810, Gainesville, FL
32611-0810. Printed 01/95.




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