• TABLE OF CONTENTS
HIDE
 Historic note
 Title Page
 Table of Contents
 Main














Group Title: Circular - University of Florida. Florida Cooperative Extension Service ; 142C
Title: Strawberry production guide for Florida
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00072520/00001
 Material Information
Title: Strawberry production guide for Florida
Series Title: Circular Florida Cooperative Extension Service
Physical Description: 17, 1 p. : ill. ; 28 cm.
Language: English
Creator: Maynard, Donald N., 1932-
Sherman, Mark, 1949-
Hochmuth, George J ( George Joseph )
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville Fla
Publication Date: 1988
 Subjects
Subject: Strawberries -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 18).
Statement of Responsibility: D.N. Maynard, G.J. Hochmuth, and M. Sherman ; edited by G.J. Hochmuth.
General Note: Cover title.
General Note: "November 1988."
Funding: Circular (Florida Cooperative Extension Service) ;
 Record Information
Bibliographic ID: UF00072520
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 20737141

Table of Contents
    Historic note
        Historic note
    Title Page
        Title page
    Table of Contents
        Table of contents
    Main
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
Full Text




HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida




/0/


S, November 1988


Circular 142C


Strawberry

Production Guide

for Florida


1.

4.


Edited by G.J. Hochmuth
Commercial Vegetable Guide Series


HF'lIonl ( ooplcilr(ivc Extension Service / Insilitulte (ol F )(od (r ti .\griiiultl urcl S- Ci(l -( cs / liv\'rsit\ of Flortida /Jo(lhn T1 \\Vteste. De'al


sl~ns~ ~R~"x7~--
~5~ a








Contents

1 Intr ductti on1
Strawberry Cultivars
Culti'ar descriptions
2 Crop Establishment

Strawberry Fertilization

Micro llutrints

8 Fertilizer placemllent
Solil)le salt injury

Drip irrigation
9 NutriIent diiso(rders
Pest Management

10 Nematode control
Disease -o)ntrol

12 Insect c(l control

13 ed Control
Nursery production

14 Harvesting & Handling

Grades
15 Definitilons
I larvesting

AccIuracI versus specdt
16 Field handling
Cooling aind storage

Loading and transporting
17 Modified atmospheres
Wholesale and retail

8 Literature cited
S Suggeested reading


Authors
D) N. Ma\yiard. Prott'ssor and Extlensiont \V'gtahlbc (:Crops
SpncR lalist. G.J. I Iocthmulth. AssokCtiat Protf'ssor ,i(nl Ext-nn-
sion \V'getable C(rop's S)'(idllist, ainl M S m;rnin. m ss,(( i-
atc \'- gctal)lul (Iops Dep artm nt, IF.S, Uni\'rsit\ A- Florind
32611.









Introduction


Table 1. Strawberries: Acreage
1984-1985.


and production for


Florida strawberries are grown on over 5000 acres
(Table 1) and comprise 4.5 percent of the total farm
value of vegetables in Florida. Approximately 90 per-
cent of the crop is produced in the Plant City area
with smaller centers of production in the Starke area,
and in Palm Beach, Broward, and Dade counties.
Most of the crop is marketed in the eastern part of
the United States. A portion of the crop is sold
through roadside markets and U-pick operations with
the latter popular toward the end of the season.


Acreage Yield per acre
Area Harvested Flats
North 600 1497
Central 4500 1696
Southeast 200 1515
State 5300 1667


Strawberry



. Cultivars
by D.N. Maynard


Selecting cultivars is one of the most important
decisions that the commercial strawberry grower
must make each season. New cultivars, to compete
with those already available, are released periodical-
ly. Glowing descriptions, tempting photographs, and
sometimes exaggerated claims accompany the
release of each new cultivar. Growers should
evaluate new cultivars as they become available, on
a trial basis to observe performance on their own
farms. A limited number of new cultivars should be
evaluated so that observations on plant performance,
plant characteristics, and yields can be recorded. It
is relatively easy to establish a trial, but very time-
consuming to collect all the data needed to make a
decision on adopting a new cultivar for large scale
production. Some factors to consider:
Yield The cultivar should have the potential to
produce equivalent or higher yields than those
already grown. Average yields in Florida range from
1400 to 1800 12-pint flats per acre. Potential yields
should be considerably higher than the average since
market constraints often limit harvest.
Earliness Early strawberries command a higher
market price than do later fruit. Accordingly, a


cultivar that produces a large proportion of its crop
in December, January, and February might be
desirable.
Disease Resistance The most economical and ef-
fective means of disease management is through the
use of cultivars with genetic resistance to disease.
Since anthracnose is the most serious strawberry
disease in Florida, it would be useful to have a resis-
tant cultivar with desirable horticultural
characteristics, and the ability to produce high yields.
Horticultural Quality Nursery production, adapt-
ability to the annual-hill system of management, and
plant habit as related to production practices, must
be acceptable.
Adaptability Successful cultivars must perform
well under the range of environmental conditions
usually encountered on the individual farm.
Market Acceptability The harvested strawberry
must have characteristics desired by the packer,








shipper, wholesaler, retailer, and consumer. Includ-
ed among these qualities are good shipping ability,
firm flesh and skin, long shelf-life, good skin color
and gloss, uniform internal color, sweet flavor,
uniform fruit shape and fruit size, and composition
including optimum vitamin C content, soluble solids,
and acidity.


Cultivar descriptions

Chandler is a patented cultivar developed by the
California Agricultural Experiment Station from a
cross between Douglas and C55. It is named for
William Henry Chandler, a horticulturist at the
University of California. Chandler is midseason,
fruiting just after Douglas. Plants are large, semi-
erect, and similar to Tioga. Fruit are large, long con-
ical to long wedge-shaped, bright red, glossy, and
borne on long, semi-erect peduncles. The fruit are
firm and ship well. Chandler is susceptible to
anthracnose.
Douglas is a patented cultivar developed by the
California Agricultural Experiment Station from a
cross between Tufts and C64.57-108. Plants are
moderately vigorous and large with sparse runner
production. Fruit are early, very large, smooth,
glossy, and dark red. They have good flavor, but are
soft. Douglas is very susceptible to anthracnose.
Dover is a cultivar developed by the Florida
Agricultural Experiment Station from a cross be-
tween Florida Belle and F71-189. Plants are medium-
sized and somewhat lighter-green than other
cultivars. Fruit are flattened, moderately pointed,
deep-red, glossy, firm, and are borne on long, thin
peduncles. Fruit may be considered too dark and


therefore overmature. Dover is resistant to
anthracnose.
Florida Belle is a cultivar developed by the Florida
Agricultural Experiment Station from a cross be-
tween Sequoia and Earlibelle. Plants have an erect-
open growth habit, are moderately vigorous, and
have good runner production. Fruit are blunt, con-
ical shaped, large, moderately firm, smooth, and
deep-red, but occasionally have white shoulders.
Florida Belle is resistant to anthracnose.
Pajaro is a patented cultivar developed by the
California Agricultural Experiment Station from a
cross between Sequoia and a breeding line. Plants
are vigorous with good runner production in the
nursery. Fruit are large, medium to long conical-
shaped, smooth, light-red, and are produced late.
Fruit are sweet and firm. Pajaro is susceptible to
water damage and very susceptible to anthracnose.
Tufts is a patented cultivar developed by the
California Agricultural Experiment Station from a
cross between Tioga and C46-5-1. Medium-sized
plants are vigorous and produce abundant runners.
Fruit are flat, wedge-shaped, medium to large, light-
red in color, moderately firm, and have a very poor
flavor until late in the season. Tufts is a late cultivar
and very susceptible to anthracnose.
Selva is a day-neutral cultivar from the Califor-
nia Agricultural Experiment Station. Selva produces
good quality fruits that are well-colored, firm, and
flat-shaped. The fruits resist abrasion but are suscep-
tible to anthracnose.

Although these cultivars are grown commercially
in the principal production areas, Hillsborough, Brad-
ford, and Dade counties, there are weaknesses and
defects associated with each of them under certain
conditions. Growers should continue to evaluate all
new cultivars as they are released.


Crop




Establishment
by G. J. Hochmuth


Field selection. Strawberries grow on most Florida
soils except for organic types. Soil must be well-
drained to facilitate water removal after heavy rains


or following large water applications for plant
establishment and freeze protection. Raised beds
should be used in areas subject to periodic flooding








from heavy rainfall. Avoid areas of known perennial
weed infestations, such as nutgrass; control of these
weeds is difficult and adds to the cost of production.
Field preparation. For sandy production sites, it can
be beneficial to plow under a cover crop such as
sorghum. The resulting organic matter will add to the
soil nutrient supply, and improve soil tilth.
A field should be leveled in a manner that will pro-
vide rapid surface drainage during the growing
season. Furthermore, drainage must move from the
field in order to prevent, water and soil in adjacent
fields from coming into the production area. Water
or soil moving into a strawberry field might be in-
fested with nematodes or disease organisms.
Bedding. (rowing st rawberries on raised beds helps
prevent flooding damage (Fig. 1). The raised beds
also provide easier harvesting of the fruit since the
berries are more accessible to pickers.
The height of the bed varies depending on the
amount of drainage needed. For most growing areas,
a height of 7 to 9 inches (measured from bottom of
row middle) is sufficient. The beds are shaped by bed
presses which can be custom-built to provide the
desired height and width.
The width of the bed depends on the number of
rows desired per bed. Fruit yield per acre may in-
crease with more rows (2). Production costs,
however, also increase because more plants, fer-
tilizer, plastic mulch, fumigant, and pesticides are
needed. High row numbers also result in denser
foliage which may make pesticide application more
difficult. Furthermore, beds with more than two
rows make picking more laborious and fruits on the
inner rows are often missed.


Figure 1. Strawberries growing on raised beds.


Bed firmness has not been adequately addressed
by research, however firmer beds may hold their
shape and retain moisture longer than softer beds.
Furthermore, moisture conductance will be greater.
The bed should be shaped so that the center is
slightly higher than the shoulder surfaces (14). This
slight central peak will facilitate movement of water
from the bed surface and provide an area to which
excess fertilizer salts can move. Avoid placing plants
in the center of beds since salt damage could result.


Figure 2. Black polyethylene mulch on strawberry beds.


Mulching. Using black polyethylene as a full-bed
cover is a standard strawberry production practice
(Fig. 2). The mulch improves fumigant effectiveness,
retains soil moisture and fertilizer, and provides
higher fruit quality. The black mulch also reduces
weed competition.
Use a mulch 0.75 to 1.5 mil thick and wide enough
to cover the beds with the edges of the mulch buried
by soil. Be sure the mulch of lower thickness is strong
enough to resist tearing throughout the season.
Prior to mulching, the beds are chemically
fumigated following all label directions for rate,
chisel spacing and placement, and waiting period.
The soil must be moist, but not wet, at the time of
fumigation and mulch application.
Fertilizer should also be applied prior to mulching.
(See the section on fertilization for detailed informa-
tion.) All of the procedures mentioned above can be
easily mechanized. A common practice is to shape,
fumigate, and fertilize the beds in one operation.
Mulch is applied in a second operation. All opera-
tions, however, can be done simultaneously with
suitable equipment.









Plants. Strawberry plants, for production, can be ob-
tained from plant producers in the northern United
States or from Florida and other southeastern plant
producers. The plants are called dormant, semidor-
mant, or non-dormant depending on the amount of
chilling temperature (below 45 0F) they have re-
ceived in the nursery. During chilling, starch content
in the upper root area increases; this enables the
plant to survive long-term storage at 28 F. Time of
fruiting and total yield are partially influenced by the
amount of chilling the plant receives in the nursery,
storage, and production field.
Growth in the production field from dormant
plants will be mainly vegetative for several months
with only periodic flowering, leading to delayed
fruiting. Usually plants received from northern
nurseries are partially dormant and have enough
starch for establishment in the field but not for long-
term storage. These plants provide adequate
vegetative growth and may even fruit earlier than
locally-produced plants. If northern plants have not
received chilling in the nursery, care must be taken
to minimize foliage loss during transplanting and
establishment since these plants have no starch
reserves. They must be handled like non-dormant,
Florida-grown plants.
Plants produced in the southeastern United States
have received no chilling prior to transplanting. Since
these plants have no starch food reserves, they
should not be defoliated or frozen. Storage periods
in a cooler for longer than 2 weeks makes establish-
ment difficult and reduces both early and total fruit
yields. Plants stored more than 4 weeks should not
be used.
Recent research with Dover and Florida Belle
showed that early (December) yields were increased
by a one-week storage period at 36 OF rather than by
transplanting directly into the field (5). Total yields
through April generally were not affected by the
storage treatment. A slight reduction in the total
yield of Dover occurred in one year out of two in-
dicating that there may be a difference among
cultivars for response to short-term storage.
There is an interaction between day length and
temperature affecting flower initiation. Shorter day
lengths are required to initiate flowers during warm
late fall and early winter growing conditions. This
effect varies with cultivars. Therefore, do not
transplant directly from the nursery too early since
vegetative growth can be excessive and fruiting can
be delayed.
Plant quality has a definite effect on plant
establishment and yield. Do not transplant
nematode-infested or diseased plants. Use
transplants that are at least one-quarter inch thick


in the crown area (1). Use plants of several cultivars
and obtain them from several sources to reduce
chances of large-scale loss.
Recent research has shown that there is an op-
timum number of leaves for a transplant when
placed in the production field (6). Dover and Florida
Belle need 4 leaves, and Pajaro needs at least 5 leaves
to be present on the transplant. If the optimum leaf
number is not known for a particular cultivar, then
a minimum of 4 leaves per plant should be needed
to facilitate establishment and early growth of the
transplants. These numbers are for plants not receiv-
ing chilling prior to transplanting and assumes no
leaves are lost during the establishment phase.
Planting date. Transplanting periods for the various
production areas in Florida are presented in Table
2. Non-dormant plants with small crowns and little
foliage develop slowly and should be planted early
in the recommended period for the particular
cultivar. Planting early in the period produces larger
plants and more fruit. If plants are transplanted too
early, however, they may become too vegetative and
fruiting may be delayed. Planting too late may result
in reduced plant growth, and later and lower yields.




Table 2. Strawberry transplanting dates for Florida
production areas.

Production Area Planting dates

North Florida Sept. 20 to Nov. 10
Central Florida Oct. 7 to Nov. 1
South Florida Oct. 1 to Dec. 1


Plant spacing. The spacing between, and within
rows depends on the number of rows per bed (Table
3). At high plant densities, pesticide spray coverage
is reduced and fruits may be missed by pickers. Fruit
rots also may increase due to reduced air circulation
around the plants.
Planting depth. Depth of planting is critical to the
successful establishment of strawberry plants. The
plants should be placed in the production field as
shown in Figure 3. Correct planting depth will pre-
vent losses due to rotting of the crown or due to root









dedication. Providing a firm bed will help keep the
plants at the desired depth by preventing bed set-
tlement or erosion.
Plant establishment. Non-dormant and partially
dormant plants require overhead irrigation after
transplanting to prevent foliage loss which reduces
plant growth and delays fruiting. These plants will
require irrigation for a period of a few days to 2
weeks. Less irrigation is needed for dormant plants
and is usually required only to cool the plant and pro-
vide soil moisture.
The objective of the irrigation is to prevent foliage
dessication while the plant root system is becoming
established. Small amounts of water are needed to
accomplish this. Irrigation should begin as soon as
plants are placed in the ground with special atten-
tion given the first few days after transplanting and
to plants with long petioles. Sprinklers should be
turned on at the first sign of wilting, and turned off
when temperatures decrease. Excessive water ap-
plication from large nozzles, used continuously, dur-
ing the establishment period can lead to fertilizer
leaching and water waste. Research has shown that


Table 3. Plant spacing for Florida Strawberries.

Between plants (in.) Plants
Bed Between In Between per acre
type beds (in.) rows rows (X 1000)

2-row 48-60 8-14 12-14 15-25
4-row 60-84 8-10 10-12 20-30


intermittent irrigation can successfully establish
plants with one-half the water consumption of con-
tinuous irrigation. Control of the "on" and "off"
cycles can be achieved by computers or time clocks.
Length of the cycles will depend on weather condi-
tions. However, a 7 minute "on" period and 8
minute "off" period should be adequate for dry
establishment periods which usually occur in late
September and early October.
Antitranspirants have been evaluated for their
ability to enhance plant establishment. In general,
they were no more effective than water.
Daughter plant removal. Runner plant production
varies with cultivar, planting date, and the amount
of chilling. It is greatest on plants placed in the field
too early, and on those that have received excessive


chilling especially from storage. Runner production
is undesirable since it leads to excessive foliage which
interferes with pesticide application and harvesting,
and may lead to reduced fruit production by the main
plant. Runners can be removed manually or by suc-
tion type rotary mowers.
Irrigation. Plant growth, fruit yields, and fruit quali-
ty depend on adequate soil moisture levels. For most
sandy soils, a soil moisture level of 7 to 10 percent
should be maintained. Amounts of water required
will vary depending on the stage of crop and on
prevailing weather conditions. Largest amounts of
water are needed in March and April when air
temperature is high and plant transpiration is rapid.
Soil in the beds should be monitored daily using one
of several types of soil moisture measuring devices.
Correct water application will ensure proper crop
development while minimizing fertilizer leaching.
Since overhead systems are used for plant
establishment and frost protection, they have been
the method of choice for routine crop irrigation.
However, drip irrigation has been shown to be a
suitable alternative. Research has shown that prop-


Figure 3. Correct planting depth is important for proper
rooting and to avoid plant damage or mortality. The
proper depth is seen with A, while B and C are too
deep and too shallow, respectively. (Drawing from Bul-
letin 841 by Albregts and Howard.)



early managed drip systems can reduce water applica-
tion by one-half (16). Drip irrigation can maintain a
more constant moisture level in the bed and reduce
fertilizer movement to the bed surface which can oc-
cur during the dry period between overhead water
applications. However, fertilizer leaching can occur
with the drip system if too much water is applied.









When using drip, apply water at, or near, the pan
evaporation rate for the area covered with mulch.
If one-half the field is covered with mulch and the
pan evaporation is 0.2 inch per day, then 0.1 inch
of water should be applied to one cropped acre. Drip
systems require special management abilities and
consultment with knowledgeable specialists prior to
installation.
Cold protection. In order to protect early yield and
maintain plant vigor, protection from freezing
temperatures should be provided. Overhead irriga-
tion is presently used for this purpose (13). As the
irrigation water freezes on the plant it provides heat
which can prevent damage to the flowers and fruits
(Fig. 4). The lower the air temperature, the greater
the amount of water required to maintain
temperatures above the damage level (30 F for
flower or fruit). Flowers are more susceptible to
freeze damage than green fruit, which are more
susceptible than ripe fruit.


severe plant damage may occur (8). With no wind,
apply 0.15 inch of water per hour for protection
down to 22 OF and 0.25 inch per hour for protection
from 18 to 22 OF. Greater amounts of water may be
needed if the water is taken from an open reservoir
rather than from a well since well water is usually
warmer in winter.
An alternative to sprinkler irrigation for freeze pro-
tection is row covers (Fig. 5). Recent research and
field demonstration has shown that certain row
covers used alone can protect strawberries equal to
sprinkler irrigation (9, 10). Advantages of row covers
over sprinkler irrigation for freeze protection in-
cludes reduced fruit cracking and rotting, reduced
field erosion, and reduced fertilizer leaching.


.. .
/**" .1 ^- *- '" ^^y"'* "'*' 's. *'i* *


Figure 4. Freeze protection of strawberries with over-
head sprinklers.




Irrigation should be turned on when the air
temperature just above the mulch in the coldest part
of the open field falls to 31 F. Irrigation should be
turned off as soon as the ice begins to melt or when
the wet-bulb temperature is above 32 oF.
Sprinklers should be spaced so that water from
each sprinkler reaches all adjacent sprinklers when
no breeze is present. With wind speeds above 10
mph, uniform water distribution is difficult and


Figure 5. Freeze protection of strawberries with a non-
woven crop cover.


NOTE: Much of the information presented above was
summarized from University of Florida Agricultural
Experiment Station Bulletin 841, Strawberry Produc-
tion in Florida.











Strawberry



Fertilization
l \' ( G.J. I lochmullt i


Prior to each cropping season, soil tests should be
conducted to determine fertilizer needs. Obtain an
IFAS soil sample kit from the county agricultural ex-
tension office for this purpose. Commercial soil
testing laboratories also are available for soil testing.
Routine soil testing will help avoid overfertilization
which reduces farming efficiency and increases risk
of groundwater pollution. The crop nutrient re-
quirements of nitrogen, phosphorus, and potassium
(designated in fertilizers as N-POs-K,O) in Table 4
represent the optimum amounts of these nutrients
needed for maximum production under most situa-
tions. A portion of this required nutrition will be sup-
plied by the native soil and by previous crop residue.
The remainder of the nutrient requirements will be
supplied by fertilizer, and this amount must be deter-
mized by soil testing. Therefore, the nutrient
amounts in Table 4 are applied as fertilizer only to
soils testing very low in phosphorus and potassium.
Automtic use of the amounts of nutrients in Table
4 as fertilizer without a soil test will possibly result
in wasted fertilizer, crop damage, reduced yields and
quality, and a risk to the environment.




Liming

The optimum soil pH range for strawberries is 5.5
to 6.5. It is not advisable to raise the pH above 6.5
because of reduced micronutrient availability.
Calcium and magnesium levels should be corrected
according to the soil test. If both elements are low,
broadcast and incorporate dolomitic lime. Where
calcium alone is deficient, use calcitic lime. If the pH
needs no adjustment but the magnesium level is low,
sources such as magnesium sulfate or potassium-
magnesium sulfate can be added to the fertilizer. It
is best to apply lime several months prior to planting.
However, if time is short, then it is better to apply
the lime any time before planting than not to apply
it at all.


Micronutrients

Since a fine line exists between adequate and tox-
ic amounts of these nutrients, they should be applied
only when needed and according to soil and tissue
testing. Table 5 provides a guide to leaf concentra-
tions of micronutrients for strawberries. Use these
amounts as a guide to monitoring the micronutrient
fertilization program.



Table 4. Fertility recommendations for mulched
strawberries on soils testing very low in phosphorus
and potassium (2-row bed system).
Nutrient Supplemental
requirements applications
Actual Ib/A
each
Actural Ibs./A application Number
Soil N-P205-KO2 N-P20O-K20 applications'
Irrigated mineral 120-160-160 30-0-20 0-2
Marl 90-120-120 30-0-20 0-2
Rockdale 90-120-120 30-0-20 0-2
'Supplemental applications can be made with a liquid injection
wheel.









Micronutrients can be supplied from oxides,
sulfates, chelates, or fritted sources. Growers using
micronutrient-containing fungicides need to consider
these sources when calculating a micronutrient pro-
gram. Avoid overuse of these pesticides since toxic
levels of micronutrients might build up in the soil.
Manganese and iron deficiencies are usually the
first micronutrient problems to appear on strawber-
ries, and this is usually associated with soil pH ex-
ceeding 6.5. Foliage application of these nutrients,
when deficiency appears, is a suitable method to cor-
rect the problem.
Boron can leach from sandy soils, and since large
amounts of water are used on strawberries, it should
be monitored closely. Amounts exceeding one pound
per acre might be toxic.


Table 5. Minimum Strawberry
element concentrations (4).


leaf blade mineral


Nutrient Leaf concentration (dry wt.)

Nitrogen 2.8 percent
Potassium 1.1 percent
Calcium 0.3 percent
Phosphorus 0.2 percent
Magnesium 0.2 percent
Sulfur 0.1 percent
Iron 50 parts per million
Manganese 30 parts per million
Boron 25 parts per million
Zinc 20 parts per million
Copper 5 parts per million
Molybdenum 0.5 parts per million


Fertilizer placement

All phosphorus and micronutrients should be in-
corporated in the bed. For soils requiring only small
amounts of phosphorus, optimum fertilizer efficiency
may be obtained from banding the phosphorus in the
bed center. Where phosphorus is low, some increase
in root development might result from the use of a
starter fertilizer solution which is high in soluble
phosphorus and applied in the hill while transplant-
ing. This starter fertilizer only supplements; it does
not replace the main fertilizer requirements.
Broadcasting excessive rates of nitrogen and
potassium increases the risk of fertilizer salt damage
to the plants. An alternative is to incorporate approx-
imately one-fourth of the nitrogen and potassium in


the bed with the phosphorus. This placement will en-
sure fertilizer presence in the transplant root zone
and will help establish the plant. The remainder of
the nitrogen and potassium may be placed in a band
1 to 2 inches deep between the 2 rows of a double-
row bed. If the 4-row system is used, increase the
recommended per acre fertilizer amount by only one-
third and place it in two equal bands between the
first and second, and third and fourth rows. The
bands are usually placed 1 to 2 inches below the bed
surface. With banding, slightly lower overall fertilizer
amounts may be used in comparison to broadcast
because banding provides for more efficient fertilizer
use.
Overfertilization or incorrect placement can lead
to severe plant damage from salt burn. Strawberries
are very sensitive to high levels of soluble salts in
the soil. This is a common problem, especially where
excessive rates of fertilizer are incorporated in the
bed or banded too close to the plant. Once diagnosed,
the only way to correct the problem is to apply large
amounts of overhead water to leach the fertilizer.




Soluble salt injury

Where general-purpose fumigants are used, at least
20 to 25 percent of the nitrogen should be in the
nitrate form. Use of natural organic nitrogen usual-
ly has not resulted in increased yields or better fruit
quality than inorganic sources (12). If poultry manure
is applied regularly to strawberry fields, rates should
not exceed 8 to 10 tons per acre per year (3). Approx-
imately one-half of the nitrogen may come from slow
release sources such as sulfur-coated urea (SCU),
isobutylidene-diurea (IBDU), or a mixture of slow
release and natural organic nitrogen. Be careful that
the nitrogen release rates of these compounds cor-
respond to crop need. Natural organic or slow-release
nitrogen sources should be considered ammoniacal
when calculating the amount of ammoniacal nitrogen
in the fertilizer.
Fertilizer potassium may be supplied from several
sources, however, the muriate (potassium chloride)
form increases the risk of soluble salt injury over
other sources of potassium. Where soluble salt prob-
lems are likely, apply a portion of the potassium from
potassium sulfate, potassium nitrate, or potassium-
magnesium sulfate.








Triple superphosphate and normal superphosphate
are excellent sources of potassium. Diammonium
phosphate should comprise only part of the
phosphorus need since research with other vegetable
crops has shown reduced yields where diammonium
phosphate was used as the sole phosphorus source
and where it was banded with the fertilizer
micronutrients.


equipment and safety requirements, as well as the
technical management details.
When fertilizing with drip, place all phosphorus,
micronutrients, and 20 percent to 40 percent of the
nitrogen and potassium in the bed. The remaining
nitrogen and potassium can be applied in weekly in-
crements corresponding to crop need. Be careful not
to apply too much water since overwatering, even
with drip irrigation, can lead to fertilizer leaching.


Drip irrigation

Drip irrigation provides a means to apply fertilizer
to the strawberry crop during the growing season,
thus potentially reducing the amounts of in-bed fer-
tilizers which are subject to leaching (15). Before fer-
tilizing with drip, be sure to consult with a
knowledgeable specialist regarding fertilizer injection


Nutrient disorders

Nutrient deficiency symptoms are sometimes dif-
ficult to diagnose. Often soil and tissue analyses can
help. Descriptions of several nutrient deficiency
disorders of strawberries, along with photographs,
are available (11).


Pest



.niManagement


Pest control should consist of an integrated pest
management (IPM) system which relies on efficient
use of all appropriate control strategies (7). Action
is taken to prevent problems and suppress damage
levels without reliance solely on chemicals. Effec-
tive IPM consists of four basic principles: exclusion
of the pest from the field, suppression of pest levels
below an economic threshold, eradication of certain
pests where deemed absolutely necessary, and plant-
ing resistant cultivars.
To carry out these principles, several steps are
taken: identification of key pests and beneficial
organisms, preventative cultural practices to
minimize pest development, pest population
monitoring by trained field scouts, prediction of loss
and risk to determine when acceptable levels of
yield and quality will be threatened, and action deci-
sion on what control measure is warranted. Consult


the appropriate Control Guide for information on
specific chemicals, safety, and chemical control
measures. All sound IPM programs include an evalua-
tion phase to assess the level of success.


This pest management information was compiled by
George Hochmuth, for strawberry growers, from the
Vegetable Sections written by Gary Simone, Fred
Johnson, and Joe Noling, respectively, in the following
IFAS publications: Disease Control Guide, Insect Con-
trol Guide, and Nematode Control Guide.











Nematode control

In Florida, sting and root-knot nematodes are
generally the most severe and widespread nematodes
attacking the strawberry. Bud and leaf nematodes
cause damage in localized areas. Damage to the
strawberry plant is dependent on numerous factors
including the number and distribution of nematodes
in the field, and by cultural and agronomic practices
by which the strawberry plants are grown.
The distribution of nematodes in the soil is usual-
ly irregular and closely related to the distribution of
plant roots and the direction of cultivation practices.
The principal ecological factors governing the
number of nematodes are temperature, moisture,
texture, aeration, and chemistry of the soil solution.
As a general rule those conditions favorable for plant
growth are equally favorable for the nematode. Host
susceptibility, tolerance, and resistance to nematode
parasitism are thus dependent on the properties of
the soil and prevailing environmental and cultural
conditions.
Sting nematode (Belonalaimus spp.) This
nematode, with a very long stylet, lives freely in the
soil and feeds on surface and interior root cells. Root
cells are destroyed by removal of cellular fluids and
by secondary invaders such as bacteria or fungi. As
a result, the size and distribution of roots are reduc-
ed and only brushes of coarse roots may remain.
Plants reduced in size may appear dormant.
Circular- to oval-shaped damaged areas appear in the
field. These areas generally increase in size as the
season progresses. Damage is generally most exten-
sive on sandy soils. Initial populations of sting
nematodes depend largely on the cover crop and
other cultural and agronomic practices which occur-
red during the intercropping period. Alternate hosts
such as crabgrass and sesbania can support large
numbers of nematodes while velvet bean and hairy
indigo are not good sting nematode hosts.
Root-knot (Meloidogyne spp.) This nematode
enters and develops entirely within root tissue induc-
ing the formation of root galls. This particular aspect
of its biology makes it more difficult to control. Galls
are one-sixteenth to one-eighteenth inch in diameter,
which is smaller than galls which form on most
vegetable crops. The galls form at the expense of
other plant parts while, at the same time, they fur-
ther influence plant growth by interfering with the
absorbtion and translocation of water and nutrients
from the soil.
Affected plants become unthrifty, wilt readily, and
may appear to be nutrient deficient. Root knot is
usually less severe on the strawberry than on other


vegetables because strawberries are grown during
cooler periods unfavorable for nematode population
growth. Most extensive damage occurs during
periods of prolonged high temperatures and drought.
Most root-knot nematodes have a very wide host
range with tremendous reproductive potential and
thus limit the types of cover crops which can be
grown.
Bud nematode (Apelenchoides spp.) This
nematode attacks the above-ground portion of the
plant, living and feeding on leaves and buds. Toxins
produced by the nematode result in smaller, crin-
kled, dark green leaves with red margins and veins.
Symptoms are described by many common names in-
cluding "french bud," "crimp," and "dwarf". Bud
nematodes are most active in warm temperatures
and, like root knot, easily spread through
transplants.
The control of all nematodes involves the use of
rotation, non-host cover crops, and approved
nematicides or fumigants. Begin field preparation 6
to 8 weeks ahead of planting so that crop debris will
be completely decayed. In the field, only the row
area needs to be fumigated, however, the entire area
must be fumigated in the nursery. Take care to pre-
vent drainage water from entering the field since it
may carry strawberry pests. Nematode sample kits,
which contain instructions and packing materials for
collecting and submitting samples to the Nematode
Assay Laboratory are available from county exten-
sion offices. Pay special attention to the source of
strawberry transplants to ensure they are not in-
fested with nematodes. For specific information on
chemicals and other control measures, consult the
nematode control guide.




Disease control

Several diseases can cause serious losses in
strawberry plant nurseries and in production fields.
A short description of each of the most serious
diseases follows.
Anthracnose. This disease, caused by the fungus
Colletotrichum fragariae, is most important in
nursery beds. The fungus first causes dark spotting,
girdling of runners, leaf petioles, and eventually









leads to dryrot of the fleshy crown. It is most destruc-
tive during periods of high temperature and abun-
dant rainfall and can be very severe in a summer
nursery. The disease also can be very important in
the fruiting field, where it can appear in three
phases, usually during warm weather. These phases
include crown rot (red, discolored streaks in the
crown), leaf spot (dark spots on leaves and petioles),
and fruit rot (brown rot of green or ripe fruit).
Diseased plants found early in the nursery should
be destroyed. Fungicide applications should be made
to prevent spread of the disease with particular at-
tention given to the nursery. Thorough coverage and
use of a sticker is recommended. Avoid high fertili-
ty in the nursery since this disease appears to be
enhanced by excessive fertility.
Rhizoctonia bud rot. Caused by Rhizoctonia
solani, this disease is most prevalent during cool,
humid periods, especially with dew and heavy fog.
The organism can attack the plant where it contacts
the soil and may grow over the plant to infect the
leaf and flower buds. Older leaves may not be at-
tacked, however, if attacked they become dry rot-
ted and lay flat on the bed surface. Single-bud plants
may lose the bud which can easily be pulled from the
remainder of the plant. The same organism causes
a fruit rot called "hard brown rot".
To control bud rot, provide adequate air circula-
tion around the plants. Avoid areas where the
disease has been prevalent particularly where heavy
cover crops of legumes have been grown. Place
transplants at the proper depth.
Common leaf spot. This disease is caused by the
fungus Mycosphaer clla f aiariae. It is favored by
warm, wet weather although it can occur any time
of the year. The spots are small at first (less than one-
eighth inch) and a purple-red color. They increase
in size to 3/16 inch and the centers become white or
gray. Numerous spots on a leaf may cause defolia-
tion. The main control measure is fungicide sprays.
The disease can be present in the nursery as well as
the production field.
Leaf scorch. This leaf disease is caused by the
fungus Diplocarpon earliana. Young spots appear
as small, purple discolorations which rapidly enlarge
to purple blotches up to three-sixteenths inch in
diameter. In these spots, small, black, glistening
bodies (the fungus fruiting bodies) appear. The pur-
ple areas may coalesce and the leaves eventually
desicate giving the plant a scorched appearance.
Control by recommended fungicide applications.
Leaf blight. This disease is caused by the fungus
Dendrophoma obscurans and is favored by warm,
wet weather. The spots are larger than those of


scorch or leaf spot. The young spots are circular and
a reddish purple color. Older spots become zonate
with a central dark brown area surrounded by a
lighter brown zone that is bordered by a purple, red,
or yellow zone. Small, black, fungal, fruiting bodies
appear in the dark brown zone. Use recommended
fungicide applications to control.
Black root. This condition is a physiological con-
dition occurring on older plants in the nursery and
thought to be related to lack of oxygen in wet soils.
The root cortex, or bark, becomes dark brown or
black and readily peels. Such roots will form new
lateral roots. Providing adequate soil aeration in the
nursery prior to digging will aid in new root
initiation.
Red stele. Caused by Phytopthorafragariae this
disease favors cool, moist soil conditions and does not
survive in Florida. It can, however, occur in Florida
where uncertified plants have been purchased from
northern areas. Heavily infected plants -become
stunted, often in patches, throughout the field. The
interior of the root, above the rot, will be red. Lateral
roots are destroyed leaving a rattail appearance.
Control by purchasing certified plants.
Southern blight. Also called sclerotium rot, this
disease is caused by Sclerotium rolfsii. Warm, moist
conditions favor the development of this disease and
it can be a problem in summer nursery beds. The
fungus attacks at the soil line involving the crown
and roots. Death can be sudden, and under moist
conditions, a white mat of mycelium may be ob-
served around the base of the plant. Small, round,
dark fruiting bodies may be found embedded in the
mat.
To help control southern blight, avoid areas where
this disease has been present on previous crops. Bury
plant material completely, by plowing.
Gray mold fruit rot. This fruit disease is caused
by Botrytis cinerea and occurs both in the field and
while transporting fruit. It attacks strawberries at
any stage of development and can be severe during
periods of cool, wet weather. Infected fruit are
covered with the gray-colored mycelium mat (mold).
Regular spray programs are needed to control this
disease. Cultivars vary for resistance to this disease
with Pajaro and Douglas being particularly
susceptible.









Verticillium wilt. This fungal disease is caused by
Verticillium albo-atrum. Older leaves have marginal
and interveinal browning and eventually collapse. It
is especially troublesome on calcareous soils of south
Florida but is not common in central Florida. There
is little chemical control for this disease although
some control can be obtained by fumigation. Use new
land or rotate with non-susceptible crops.
Leaks or whiskers. This fruit rot, caused by
Rhizopus stolonifer, is of most importance during
shipping although it can be found in the field. It
develops under conditions of high temperature and
moisture. The fungus attacks damaged fruit causing
a loss of juices (leak). The fruits become covered with
a loose cottony growth of mycelium (whiskers). The
fruits settle in the container and are matted together
by the mycelial growth.
Control of this disease involves care during pick-
ing, grading, and shipping to ensure no damage to
the fruits. Proper cooling during storage and ship-
ping will help prevent the development of this
disease.




Insect control

Spider mites. These pests feed on plant leaf sap
causing stunting of the plant. Often, infested areas
in the field have a yellowish or brown color. Several
species of mites can affect Florida strawberries. This
will become a serious problem if routine observations
or scouting is not carried out. The most prevalent
mite is the two-spotted spider mite, although the
cyclamen mite may occur occasionally. Control of
mites is accomplished by proper miticide applica-
tions. Complete foliage coverage is needed to con-
trol mites which tend to populate the undersides of
the leaves. Failure of a chemical to control all infesta-
tions may indicate the presence of several mite
species.
Wireworms. These insect larvae are smooth,
round, and shiny, varying in color from pale yellow
to dark brown. The adult is a brown to black "click
beetle". The larvae bore into the thickened portion
of the root and may even bore into fruit leading to
rotting of the plant or fruit. Clean cultivation and
crop rotation are helpful practices, however, op-
timum control is achieved by fumigation and
insecticides.
Cutworms. Several species of cutworms attack
strawberries by cutting leaves and plants. They can
also feed on strawberries, sometimes cutting the


berry from the plant. Control measures are similar
to those used for wireworms. Baits are effective if
applied late in afternoon. Sprays must be directed
at the crown.
Armyworms. Larvae of a moth, these worms are
about 1 to 11/2 inches in length when grown. They
vary in color from tan to green to black and have 3
yellowish-white hair lines down the back. Next to
these lines is a wide dark stripe and next to it is a
wavy yellow stripe blotched with red. Army worms
can be distinguished by a light-colored inverted "Y"
on the forehead. Recommended insecticides will con-
trol the fall armyworm.
Lesser cornstalk borer. This insect can be a
serious pest of strawberries at times. It attacks other
crops and has several wild hosts such as nutgrass.
Small round holes in expanding leaves are the first
sign that this insect is present. Plants later wilt after
the insects bore into the crown. Foliar applications
of insecticides are used for control. Irrigation is quite
effective in reducing damage from this pest.
Pesticide sprays should consist of sufficient volume
to wet crown and root areas.
Mole crickets. This insect is most severe in the
field during the fall but can also be destructive in the
nursery. It affects plants most by burrowing in the
soil which damages roots and hastens drying of the
soil. Control of mole crickets involves the use of in-
secticide baits applied to warm, moist soil before
mulch application.
Citrus root weevil. The larva (a large, white, fat
grub) often severely damages strawberries in Dade
county. The chief damage is caused by larvae tun-
neling through the crowns. The same controls used
for wireworms will control the root weevil.
Pameras. This insect is a member of the chinch
bug family and resembles small, yellow ants in size
and color but has rapid movements. The feeding of
pameras causes a fruit syndrome known as "but-
tons" in which young fruits fail to grow and become
hard, dry, and brown. Outer leaves turn brown and
die, and if disturbed, these leaves reveal the insects
which scatter for cover. Insecticide application is the
most effective control measure.
Strawberry leaf roller. This insect is more
prevalent in the nursery rather than the production
field. A gradual change in the color of leaves from
green to silver may be the first indication of this in-
sect. A heavy infestation results in many folded
leaves exposing the silver color underside of the leaf.









Larvae feed on the leaf surfaces causing leaves to
turn brown and die. Insecticides are used to control
this insect, however, timing is critical since control
is difficult once the insect is inside the leaf roll.
Flower thrips. This rasping insect is very small,
soft-bodied, yellowish in color, and very active. They
can be numerous in flowers where they feed on
pistils, stamens, and young fruits resulting in blossom
drop or the formation of hard, brown fruits that fail
to develop. Insecticide applications that ensure
penetration of the foliage are the most effective
means of control. Do not over use insecticides against
flower thrips since these chemicals often destroy
beneficial predators of the two-spotted mite.
Other insects. Insects of lesser importance include
field crickets, flea beetles, root worm, grasshoppers,
ants, root aphids, white grubs, slugs, and snails.




Weed control

Optimum vegetable production depends on suc-
cessful control of weed species. Weeds reduce yields
by competing with the crop for nutrients, water, and
light. In addition, certain weeds may be alternate
hosts for disease organisms and insects. It is impor-
tant to understand certain weed problems because
they can differ in the same field and in different
years. Annual grasses and broadleaves sprout from
seed and complete their life cycle in one year. These
weeds must be anticipated and control strategies
planned before the crop is established. Perennial
weeds, such as bermuda grass, live continually from
year to year, and their presence can be determined
prior to field preparation.
An important aid in weed control programs, is a
weed map. Weed maps, developed through the
season, will detail areas in the field where specific
weeds exist, and as a result, help the grower plan
a more efficient weed control strategy.
Control of weeds is similar to control of plant
diseases and insects, since it involves an integrated
management system where several control strategies
may be combined. These measures include
mechanical means, crop rotation, cover cropping,
crop competition, mulching, and herbicides.
Mechanical means include such control measures
as plowing, disking, cultivation, hoeing, mowing, and
hand-pulling. Cultivate only deep enough to achieve
weed control. Excessive cultivation could damage
crop roots, or lead to rapid soil drying.


Crop rotation helps control weeds by providing a
different crop/weed interaction. Different weed con-
trol strategies might be available on one crop that
may not be available, or as effective for another
crop. Rotating to a crop that is more competitive with
a certain weed or, for which a specific herbicide is
labeled, might be a good strategy for dealing with a
weed problem.
Cover cropping allows a grower to place a crop in
the field to compete with weeds during the "off-
season". Competition reduces the weed's ability to
reproduce, and thus can reduce the potential for
weed problems in the next season.
Special attention needs to be placed on ensuring
the crop's capability to compete with weeds. This in-
cludes providing optimum water, fertilizer, and pest
control so the crop has a competitive advantage. Op-
timum plant and row spacing will provide the highest
economic degree of crop competition with weeds.
Careful selection of approved herbicides can be an
effective tool for weed control. Care must be exer-
cised to ensure the materials are used at proper rates
and timing to avoid crop damage.
The use of black polyethylene mulch on strawberry
beds will greatly reduce weed problems in the row.
Fumigants used under mulch will help reduce weed
and pest problems. Weeds may still appear in
strawberry plant holes, in the mulch, or in alleys be-
tween beds. Usually timely application of a herbicide
with a shielded sprayer or manual cultivation will
remove weeds in alleys.




Nursery production

Most Florida strawberry growers use northern-
grown plants. However, some growers still produce
all or a portion of their own transplants. For those
interested in nursery production practices, the
following general points are offered. For more detail,
consult Bulletin 841, Strawberry Production in
Florida (4).
The largest problems with nursery production are
disease, nematode and weed control, and labor sup-
ply shortages for nursery care and plant digging.
Select a well-drained site, one that has not been in
fruit production the same year. The site should be
broadcast fumigated.








For winter nurseries, plants should be fertilized
with 20 pounds per acre each of nitrogen,
phosphorus, and potassium by banding 2 to 3 inches
to the side of the plant and 1 to 2 inches deep. Ap-
ply 10 to 30 pounds per acre of each nitrogen,
phosphorus, and potassium over the beds by broad-
casting every 2 to 3 weeks to maintain rapid growth.
Sprinkler irrigate to wash fertilizer from leaves.
For the summer nursery, the fertility program
should be reduced because anthracnose can be
enhanced under high fertility levels. Reduce the
broadcast fertilizer by about 50 percent until late
August or early September when it can be increased
to provide larger plants. Watch closely for
anthracnose.
The plants should be grown on beds no higher than
required for adequate drainage. Beds are usually 4
to 6 feet between centers and firmly pressed. Plants
are grown in a single row per bed.
For the winter nursery, use a plant spacing of 2
feet for prolific plant producers and 1 to 1I feet for


poorer producers on 4-foot beds. Summer nurseries
may require 2 to 3 feet between plants. High den-
sities produce undesirable plants with small crowns
and long leaf petioles.
The winter nursery is planted in January and the
summer nursery is planted in late May or early June.
Use the later date for cultivars very susceptible to
anthracnose. Store local plants for 6 to 8 weeks in
a cooler prior to winter nursery planting. Remove
flowers as they appear. Out-of-state dormant plants
do well in either nursery.
Weed control is important in the nursery. Fumiga-
tion controls many weeds but some may have to be
cultivated or manually removed.
Soil moisture is critical to proper rooting of run-
ners. Attention should be given to maintaining ade-
quate soil moisture.
Maintain careful attention to disease and insect
problems. Stay on a good control program as outlined
in the Pest Control section of this guide.


Harvesting




and Handling
byl M. Sherman


Strawberries are one of the most delicate and
highly perishable fruits. Their nonclimacteric
physiological characteristics dictate that they must
be harvested in an essentially ripe condition. This is
in contrast to climacteric fruits like the tomato where
fruit can be harvested at a mature (but unripe) stage
with the postharvest environment regulated to con-
trol ripening. Therefore, the successful harvesting
and handling of strawberries requires precise
management of all operations.
With many fruits and vegetables the harvesting,
grading, and packing are done by different people.
Harvesting is done by pickers in the field, field con-
tainers are transported to a packinghouse, grading
is done by graders along a grading area, and packing
is either done by hand or machine. With strawber-
ries, the harvesting, grading, and packing operations
are all done by one person in the field.


From a product quality standpoint, this can be very
advantageous because the number of handing steps
is dramatically reduced and this reduces the possibili
ty of physical damage to the fruits. However, this
harvesting system places more importance and
responsibility on the pickers and the harvest crew
supervisors. If the fruits are not picked and packed
carefully, all other attempts to maintain fruit quali-
ty are useless.










Grades

United States grade standards for strawberries
allow for three grades, U.S. 1, Combination, and U.S.
2. The principal grade is U.S. 1. Although Florida
shippers may not use U.S. grades for shipping, these,
or similar grades, are used for inspection purposes
at destination. Therefore, all growers should be
aware of the grade specifications. If the strawber-
ries do not meet the grade standards when they are
picked, then it is simply impossible for them to make
grade at destination.
Strawberries of one variety or with similar varietal
characteristics with the cap (calyx) attached, which
are firm, not overripe or undeveloped, and which are
free from mold or decay and free from damage
caused by dirt, moisture, foreign matter, disease, in-
sects, mechanical or other means are U.S. 1. Each
strawberry has at least 3/4 of its surface showing a
pink or red color.
(a) Size Unless otherwise specified, the
minimum diameter of each strawberry is not less
than 3/4 inch.
(b) Tolerances In order to allow for variat ions
incident to proper grading and handling the follow-
ing tolerances, by volume, are provided as specified.
Defects Not more than 10 percent for strawber-
ries in any lot which fail to meet the requirements
of this grade, but not more than one-half of this
tolerance, or 5 percent, shall be allowed for defects
causing serious damage, including therein not more
than 2/5 of this latter amount or 2 percent for
strawberries affected by decay. (2) Off-size Not
more than 5 percent for strawberries in any lot which
are below the specified minimum size.





Definitions

Overripe means dead ripe, becoming soft, a con-
dition unfit for shipment and necessitating im-
mediate consumption.
Undeveloped means the fruit has not attained a
normal shape and development due to frost injury,
lack of pollination, insect injury or other causes.
Button fruits are the most common type of the
underdeveloped condition.
Damage means any defect or combination of
defects which materially detracts from the ap-
pearance or the edible or shipping quality of the
strawberries.


Serious damage means any specific defect de-
scribed in this section; or an equally objectionable
variation of any of these defects, any other defect,
or any combination of defects, which seriously
detracts from the appearance or the edible or ship-
ping quality of the strawberries. The following
specific defects shall be considered as serious
damage: soft fruits, badly deformed fruits, badly
bruised fruits, decayed or leaky fruits, fruits badly
caked with dirt, and fruits with less than half of the
surface showing a pink or red color.




Harvesting

Strawberries are packed directly into fibreboard
flats containing 12 one-pint baskets. The open-mesh
molded plastic baskets are the most widely used at
this time. The more flexible baskets are less damag-
ing than the more rigid ones. Pickers should always
use a picking cart or stand to keep flats off the
ground.
Fresh market strawberries must be picked with
their calyx (caps) on. Pickers should hold the fruit
gently between the thumb and first two fingers, then
using a twist of the wrist, snap the stem off.
Strawberries for long distance shipments should be
picked with not more than 3/4 of the surface area
pink or red color. This may seem strange at first, but
remember that you are not picking berries for you
to eat today. These fruits are going to distant markets
and will not be consumed for several days. Harvested
strawberries are alive and will continue to ripen and
soften after they are picked. Soft, bruised, and over-
ripe fruits should be discarded because they are con-
sidered "serious damage" in the grade standards.
Two soft or overripe fruits in a pint containing 20
fruit would constitute 10 percent serious damage and
throw the strawberries out of grade.
Fruit should be handled gently at all times.
Anytime a fruit is bruised, that area will discolor. In
addition, bruising increases water loss. Trying to hold
too many fruit at one time will result in bruising.
Harvested strawberries should be placed, not
dropped, in the flats. Flats should not be overfilled
because stacking will cause crushing.









Pickers should discard any strawberries with
decay. The grade standards allow for only a 2 per-
cent tolerance for decay. Therefore, this must be
strictly enforced in the field. A few decayed fruit
could throw an entire load out of grade. Severely
misshapen, sunburned, undersized, or otherwise un-
marketable fruits should be removed from the plants
and dropped in the alley.
The importance of picker training and supervision
cannot be overemphasized. The quality of the pack
depends on the picker. A scoresheet similar to the
one in Table 6 should be used as an initial training
aid and as a tool for evaluating the performance of
pickers during the entire season. A financial incen-
tive could be offered to pickers that pack in-grade
strawberries for the season.





Accuracy versus speed

The accuracy of the pickers is essential to making
a quality pack. Good pickers average 5-6 flats per
hour in good, high-yielding strawberries. Accuracy
should not be sacrificed for speed. Proper training
early in the season will develop fast, accurate
pickers.
Speed of harvest can also be increased by manag-
ing crews and laying out fields to minimize the time
pickers spend traveling between the check-in station
and the strawberries to be harvested. Harvesting and
checking in flats from both ends of a field can save
considerable time.


Field handling

Every time a flat of strawberries is handled, the
chance for physical damage increases. Field stack-
ing the filled flats directly onto the pallets to be used
for shipping is the most efficient practice, since this
eliminates the need for further handling of individual
flats. Travel over rough roads can cause considerable
damage to packed strawberries.
Harvested strawberries can deteriorate rapidly at
normal field temperatures (Fig. 6). Therefore, the
field handling after harvest needs to be expedited.
The key to delaying strawberry deterioration is prop-
er temperature management. Steps that can be taken
in the field include: 1) keep harvested strawberries
in the shade (fruit exposed to the sun and 72 OF air
increased in temperature as much as 160F in one
hour); and 2) transport strawberries to a cooler as
soon as possible.


Cooling and storage

Prompt, thorough cooling to near 32 OF soon after
harvest is essential for maximizing strawberry quali-
ty and shelf-life. Forced-air cooling is the preferred
method for removing field heat from strawberries.
Temperatures should be measured with a reliable
electronic thermometer. Fruit pulp temperatures
should be taken prior to cooling and during cooling.
Fruit temperatures should be measured on the warm
side of the cooler (inside of stack in systems that
draw air through the berries; outside of stack in
systems which blow air through the berries).
Strawberries coming from the'field at 65 F do not
need to be cooled for as long as fruits arriving at
90 F. Leaving strawberries in the forced-air cooler
longer than necessary can lead to undesirable water
loss because of the rapid air movement. On the other
hand, inadequate cooling can lead to rapid deteriora-
tion due to high temperatures. For every 18 OF above
32 0F, strawberry deterioration roughly doubles.



Table 6. Strawberry grading scoresheet based on grade
standards for U.S. No. 1 fresh market strawberries. Per-
cent of sample is based on the count of fruits in a pint.

Date
Picker


Serious Damage
Decay (not more than 2% allowed)
Soft, bruised, or over-ripe fruits
Badly misshapen
Underripe (less than 1/2 of fruit
surface with pink or red color)
Subtotal for serious damage (not
more than 5% allowed)
Other Defects
Undersize (lless than 3/4" in
diameter) (not more than 5
percent allowed)
Other damage (calyx removed,
insect damage, dirty fruits)
Subtotal for other defects
Total for all damage (not more
than 10 percent allowed)


% of Sample









Cooling schedules should be utilized to maximize ef-
ficiency. Use of a schedule allows cooling times to
be adjusted based on the initial temperature of the
berries. The local extension agent can assist in
developing a cooling schedule.
Following cooling, strawberries should be stored
in a cold room maintained at 32-34 OF. Strawberries
are highly perishable and holding periods should be
kept as short as possible.





Loading and transporting

Modern strawberry loading facilities are enclosed
and provide continuous refrigerated handling of the
fruit from the cooler to the truck. Trailers that are
to carry strawberries should be precooled to 34 F
prior to loading. Center loading of the palletized
strawberries (Fig. 7) results in more uniform fruit ar-
rival temperatures because contact with potentially
hot or cold places in the trailer walls is eliminated.
Strawberries could be shipped in mixed loads with
other products having similar temperature re-
quirements (320 to 34 F). This may include iced
products when precautions are taken to keep the
strawberry packages from coming in contact with the
melting ice. Some mixes may not be compatible with
respect to odors (onions and garlic). Strawberries
should never be shipped in mixed loads with chill-
ing sensitive products such as avocados, tomatoes,
cucumbers, peppers, eggplant, squash, etc.

100
goo
so --
90,
80

S 70-
60

50 -
S40
a /
30 /
20 /-- Marketble fruit
20 Fruit showing
10 / decay
10

0 1 2 3 4 5 6 7 8
Hours at 85'F

Figure 6. Effect of delaying cooling on strawberry
quality (from Mitchell, F.G., E.C. Maxie, and A.S.
Greathead. 1964.) Handling strawberries for fresh
market. Circular 527. Univ. of Calif. Coop. Ext.
Service p.16.


Modified atmospheres

Elevated carbon dioxide (CO,) levels between 10
to 20 percent are known to retard strawberry decay
caused by Botrytis. Recent studies at the University
of California indicated that carbon dioxide treatment
was of little benefit when storage temperatures were
maintained below 41 F. Therefore, if transit and
storage temperatures are maintained below about
Side-loaded Center-loaded


I--,- i

28 -- 28 0 0




Figure 7. Effect of trailer loading patterns on the
number of strawberry flats per pallet in contrast with
an outer wall.


36 OF there is little need for the carbon dioxide treat-
ment. Practically speaking, considerable evidence in-
dicates that strawberries are often exposed to
temperatures above 40 F during transport and in
these cases the carbon dioxide treatments may be
beneficial.
With solid loads, the modified atmosphere may be
established for the entire transport vehicle. Plastic
shrouds are, more commonly, placed over individual
pallets equipped with a base that can be sealed. Car-
bon dioxide is then injected into the package to
establish the desired atmosphere.





Wholesale and retail

Even under optimum handling conditions,
strawberries will have deteriorated to some degree
during harvesting and transport. It is extremely im-
portant that low temperatures be maintained dur-
ing wholesale and retail handling. Often a plastic
overwrap or cover is placed on the pints of strawber-
ries at retail. This is primarily to prevent pilferage
but it also helps reduce water loss during retail
display.







Literature cited

1. Albregts, E. E. 1968. Influence of plant size at
transplanting on strawberry fruit yield. Proc. Fla.
State Hort. Soc. 81: 164-167.
2. Albregts, E. E. and C. M. Howard. 1979. Effect
of two and four-row beds with drip or sprinkler
irrigation on strawberry fruiting response. Proc.
Fla. State Hort. Soc. 91: 73-74.
3. Albregts, E. E. 1981. Effect of poultry manure
on strawberry fruiting response, soil nutrient
changes, and leaching. J. Amer. Soc. Hort. Sci.
106: 295-298.
4. Albregts, E. and C. Howard. 1984. Strawberry
Production in Florida. Univ. Fla. Res. Bull. 841.
5. Albregts, E. E. and C. M. Howard. 1985. Short-
term cold storage and soil fertility during plant
and fruit production on growth and fruiting of
strawberry. HortScience 20: 411-413.
6. Albregts, E. E. and C. M. Howard. 1985. Correla-
tion of leaf number at transplanting to
strawberry fruit yield. HortScience 20: 415-416.
7. Anon. 1978. IPM, an integrated pest manage-
ment primer. Fla. Coop. Ext. Ser. Misc. Pub.
IPM-1.
8. Harrison, D. S., J. F. Gerber, and R. E. Choate.
1974. Sprinkler irrigation for cold protection. Fla.
Coop. Ext. Ser. Circ. 348.
9. Hochmuth, G. T., S. R. Kostewicz, and S. J.
Locascio. 1986. Row covers for freezer protec-
tion of strawberries. Proc. 19th Nat'l. Agric.
Plastics Congress. 175-184.
10. Hochmuth, G. J., S. R. Kostewicz, S. J. Locascio,
E. E. Albregts, C. M. Howard, and C. D. Stanley
(in press). Freeze protection of strawberries with
floating row covers. Proc. Fla. State Hort. Soc.
11. Johanson, F. 1982. Hunger in strawberries. K and
H Printers, Inc. Everett, Washington.
12. Locascio, S. J. 1964. Effects of fertilizer place-
ment, organic nitrogen and time of mulching on
strawberry yield. Proc. Fla. State Hort. Soc. 77:
194-198.
13. Locascio, S. J., D. S. Harrison, and V. F. Nettles.
1967. Sprinkler irrigation of strawberries for
freeze protection. Proc. Fla. State Hort. Soc. 80:
208-211.

Illustration and Graphic Design bI' Katrina Hautler


14. Locascio, S. J. 1970. Strawberry yield and soil
nutrient levels as influenced by plant population,
fertilizer rate, and bed shape. Proc. Fla. State
Hort. Soc. 84: 160-162.
15. Locascio, S. J., J. M. Myers, and F. G. Martin.
1977. Frequency and rate of fertilization with
trickle irrigation for strawberries. J. Amer. Soc.
Hort. Sci. 102: 456-458.
16. Myers, J. M. and S. J. Locascio. 1972. Efficiency
of irrigation methods for strawberries. Proc. Fla.
State Hort. Soc. 85: 114-117.


Suggested reading
This guide presents general recommendations for
commercial production of strawberries in Florida.
Because chemical recommendations and production
costs change rapidly, they are not presented in this
guide but can be obtained from several of the follow-
ing IFAS publications:

In sect Control Guide. (Available on \VAX).
Chemical Control Guide for Foliar Diseases of
Vegetables. Plant Pathology Report 6.
Plant Disease Control Guide. (,Available on
VAX).
Guidelines for Effective Control of Plant Dis-
eases, Plant Pathologyv Report 20.
Nem~atolde Control Guide (also a\. il Ii I1, on
VAX via FAIRS).
Weed Control in Florida \Vegetables STI-87.
Commercial Vegetable Fertilization Guide. Cir-
cular 225-C.
Commercial Vegetable Varieties for Flori(da. Cir-
Cular 530-A.
Costs a nd Retcurns From Vtegetatble Crops in
Florida. With Comparisolls. Economic Infor-
mlationl Report 186.
Florida Stra\vbetrry Production ali nd Marketing
Facts, Econiomic Information Report 158.
Strawherry Production in Florida, Bulletit 841.
Diseases. Nematodes, anti Insects \Afecuting
Stra\twherries il Florida, Bulletin 852.

These publications are continually revised (be sure
to get the latest edition).
PRECAUTIONS: Pesticides must be used wih ex-
treme care. Always read and follow the label recom-
mendations to find out which crops a pesticide may
be used on, what dosage to use, and what amount
of time should lapse between last application and
harvest. Study suggestions for safety.


This publication was produced at a cost of $2,454.17, or 61.0 cents per copy, to inform growers and county
extension staff about information on commercial strawberry production. 9-4M-88


COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORIDA, INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES, K.R. Tefertiller,
director, in cooperation with the United States Department of Agriculture, publishes this information to further the purpose of the May 8 and
June 30,1914 Acts of Congress; and is authorized to provide research, educational information and other services only to individuals and institu-
tions that function without regard to race, color, sex, age, handicap or national origin. Single copies of Extension publications (excluding 4-H
and \buth publications) are available free to Florida residents from County Extension Offices. Information on bulk rates or copies for out-of-state
purchasers is available from C.M. Hinton, Publications Distribution Center, IFAS Building 664, University of Florida, Gainesville, Florida 32611. Before publicizing
this publication, editors should contact this address to determine availability.




University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs