Blackberry production in Florida

Material Information

Blackberry production in Florida
Translated Title:
Circular / Agricultural Extension Service ; no. 325 ( English )
Sherman, W. B.
Westgate, P. J.
Place of Publication:
Gainesville, Fla.
Agricultural Extension Service, IFAS, University of Florida
Publication Date:


Subjects / Keywords:
Plant roots ( jstor )
Blackberries ( jstor )
Canes ( jstor )
Spatial Coverage:
North America -- United States -- Florida

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.


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Copyright 2005, Board of Trustees, University
of Florida





Agricultural Extension Service
Institute of Food and Agricultural Sciences
University of Florida, Gainesville

MAY 1968


Introduction .. ----------- --.--..........---------- 3

Varieties ----....-----------------------.---------- 3
Propagation 3--... ...-- ......-............--- ---..~~~~------- 3

Leafy stem cuttings ............---------....-------------------- 3

Root cuttings ...........-.... .. .------ .. ......... .... ... 4

Planting -----........ ........... ......... ... ...----------..........-. 4

Site selection .-------.-.........--------------.----------- 4
Setting, spacing and trellising --------------- 5
Cultural Practices -.... ....... ......... ........----- ---------- ----- 5

Cane removal .......-----------.....-- ...-.......... .- 5

Weed control .--..--.. --------------.. ..............--.---..-...--..-
Fertilizing -........--.........--- ....... ..- ---------------- I

Irrigation ------...-- ...---.. ......- ....- ...
Pollination----.-.. -----............--------------- ...

Harvesting and Marketing --.-------..... ..............

Insects .......-----------.........--------... ----.-...------- --.

Diseases ------ ---.---------------.

(Acts of May 8 and June 30, 1914)
Agricultural Extension Service, University of Florida, and United States
Department of Agriculture, Cooperating, M. O. Watkins, Director


W. B. Sherman and P. J. Westgate2


Commercial blackberry produc-
tion has become important in Flor-
ida because the fruit from recently
introduced varieties can reach the
market earlier than fruit produced
in other regions. In addition, new
varieties produce high yields of
large, attractive fruit. At present,
Florida production is aimed at the
fresh fruit market; however, the
development of a processing mar-
ket is desirable for growth and
expansion of the blackberry in-

The major blackberry varieties
grown in Florida during the last
10 years, 'Floragrand,' Oklawa-
ha,' and 'Brazos,' have replaced
'Marvel,' 'Advance,' 'Regal-Ness,'
and 'Boysen' types. Plantings have
been small, usually ranging from
1/. to 5 acres. A few larger plant-
ings are in the range of 10-20
acres. Interest in the culture of
this crop is increasing, and esti-
mates of up to 2,000 cultivated
acres have been projected by 1975.


Blackberries include both the
erect and trailing types and are re-
ferred to as erect blackberries and
dewberries respectively.
The recommended varieties for
Florida are: (1) the early fruiting,

trailing types, 'Oklawaha' and
'Flordagrand,' released by the
Florida Agricultural Experiment
Station, and (2) the later fruiting,
semi-erect type, 'Brazos,' intro-
duced from Texas.

Blackberry plants will normally blackberry plants in Florida have
propagate themselves throughout been propagated by leafy stem
the summer by root suckering and cuttings under mist. The stem cut-
natural layerage. Thus, two main ting method lends itself more
methods of propagation are avail- readily to the trailing types which
able. sucker poorly from the roots. Cut-
Leafy Stem Cuttings. Most tings can be obtained from an
Excerpts in this circular have been taken from Circular 294 by J. S. Shoe-
maker and R. M. Davis, University of Florida. Writing of the sections on
insects and diseases was coordinated with J. E. Brogdon, Entomologist, and
R. S. Mullin, Pathologist, Agricultural Extension Service, University of
2 Assistant Horticulturist and Horticulturist with the University of Florida
Agricultural Experiment Stations.

Figure 1. A typical propagating bed for leafy stem cuttings.

established plant, using the new
canes while their growth is still
Make cuttings 4 to 6 inches long,
and insert them 1 to 2 inches
into the rooting media. A 1/L per-
lite and 1/, peat mixture provides
a well drained, sterile medium de-
sirable for good rooting and nema-
tode free plants. Rooting occurs
within five to six weeks. If each
cutting is rooted in a peat pot they
can be used for direct field plant-
ing while the plants are quite
young. Otherwise the rooted cut-
tings may be lined out in a nursery
row until they become well estab-
lished on their own roots.
Trailing types can also be propa-
gated by covering tips of new
canes on an established plant with
soil in summer. The rooted tips are
dug and planted before the follow-
ing spring.

Root Cuttings. All blackberry
varieties will propagate from root
cuttings although this method is
most often used with the 'Brazos'
types. Root cuttings are economical
since the desirable fleshy roots are
easily dug. Root pieces of pencil
size are most likely to produce a
strong vigorous plant for this size
is neither too old nor too small.
Roots are cut into 4 to 6 inch
lengths, tied in bundles, and stored
in damp burlap or polyethylene
bags until planting. Planting root
pieces directly into the field often
results in uneven growth the first
year but a good stand is usually
Sucker plants growing from
roots may also be dug and planted.
The 'Brazos' types sucker more,
readily than the trailing types
making it possible to obtain a con-
siderable number from one plant.


Site Selection. The blackberry
is adapted to a wide range of soils,
providing they are well drained.

On mineral soils, a slightly acid
range pH 5.5 to 6.5 should
provide optimum growing condi-

tions. Little information is avail-
able for peat and muck soils, but
blackberries have been grown with
some success on muck which tested
as low as pH 4.7 where adequate
drainage was maintained.
Returns from a high-yield plant-
ing justify using good land for
blackberries. A site with good air
drainage and frost protection is
especially important for the early
blooming, trailing type. Mature
blackberry plants are seldom dam-
aged by cold; however, damage to
flowers and young fruit is fre-
quently a problem in early spring.
Frost hazard begins as soon as
buds have swollen and can continue
to affect even berries that have set.
Open blossoms and young berries
are injured by a minimum tem-
perature of 280F. The pistils of
open flowers may be killed by frost
while the petals escape. In such
cases the blossoms appear to be
normal but do not set fruit. The
fruit-producing canes of 'Okla-
waha' and 'Flordagrand' may be
weakened or killed at temperatures
ranging below 20F.
Setting, Spacing and Trellising.
- The cool months are best for
setting blackberry plants, but they
may be planted throughout the
year. If planting is done during
warm, dry weather, irrigation is
With trailing varieties, the canes
extend several feet from the plant
center so that the growth of adja-

cent plants becomes intermingled.
Depending on the vigor with which
plants are grown and the amount
of capital outlay, plants may be
spaced 5 to 10 feet apart in the
row between posts that are 20 to
40 feet apart. The spacing between
rows is often 10 to 12 feet, but op-
timum spacing depends largely on
the cultivation equipment to be
Set plants of the semi-erect
'Brazos' 4 to 6 feet apart in the
row. When set directly in the field,
space root-pieces slightly closer
than nursery plants to insure a
uniform stand more quickly.
For easier picking, tillage, and
cleaner fruit the canes must be
supported off the ground. When
vigorously grown and properly
pruned the 'Brazos' requires no
trellis; however, 'Oklawaha' and
'Flordagrand' require a trellis.
There are a number of methods
for trellising and a common one
consists of three evenly spaced
horizontal strands of wire with the
top one five feet high. Wire is sup-
ported by well anchored end posts
with smaller sturdy posts within
the row.
It is best to get at least one new
cane tied to the top wire. Later de-
veloping canes can then be drooped
over the wires, but not bent sharp-
ly. Thorns tend to hold the addi-
tional canes on the trellis without

Cultural Practices

Cane Removal. Unlike most
other fruit plants, the blackberry
has perennial roots with biennial
tops tops which grow one sum-

mer and produce fruit the next
spring. Fruiting canes die after
harvest and are of no further use
in the planting. In northern pro-

duction areas, only the fruiting
canes are removed after harvest,
leaving the new canes for produc-
tion the succeeding year. Because
of the long growing season in Flor-
ida, the general practice among
growers has been to remove all tops
to ground level immediately after
harvest. The brush which results
harbors insects and diseases and
should be burned. New growth
which then develops from the
crown will fruit the following
spring. This process of top re-
moval and new cane development
is repeated each year for the life
of the planting.
Weed Control. Weed control
is very important in establishing
and maintaining a vigorous and
highly productive blackberry
planting. Hoeing is important as a
means of encouraging a good start
for a new planting. It is also a good

practice to hoe near plants in es-
tablished plantings where disks
and other cultivating equipment do
not reach the weeds. Cultivation
in between rows should be shallow
since deep cultivation destroys
part of the blackberry root system
and retards growth.
Insufficient work has been con-
ducted on the use of herbicides as
cultural tools for blackberries to
outline a good program; but, they
show considerable promise. If
herbicides are to be tried it is a
good practice to treat only a small
area for a trial basis. Always fol-
low directions on the label.
Casoron and Simazine are pre-
emergent herbicides. They should
be applied to bare soil prior to
weed growth or after cultivation
at the rate of 4 pounds active in-
gredient per acre on established
plantings. Two periods offer good

Figure 2. An example of clean cultivation in the planting.


-. _- ..>' .. -?~-r -. 4

opportunities for application: (1)
immediately before spring growth
begins, or (2) at the time of
old cane removal. These two her-
bicides give best results when
applied to moist soil or when over-
head irrigation is applied immedi-
ately after application.
With Simazine always avoid
direct contact with the blackberry
plant and do not apply when fruit
is present. DO NOT cultivate the
treated area until weed seeds begin
to germinate within it. Cultivation
might damage the blackberry
plants if the applied Simazine is
mixed with soil in the root zone.
Casoron should be distributed
uniformly on the soil surface and
incorporated to a depth of 1 to 2
inches. Incorporation should be
accomplished immediately follow-
ing application for best results.
Fertilization. Until more in-
formation becomes available, the
following fertilization procedures
are suggested:
About 3 weeks after planting ap-
ply 1/5 pound per plant of a mixed
fertilizer (e.g., 8-8-8) in a uniform
band 8 to 12 inches wide around
each plant, keeping the band 6 to
12 inches from the plants.
If the planting were made dur-
ing the late fall or winter, no ad-
ditional fertilizer need be applied
until late February or early March
when 1/3 pound of a mixed fer-
tilizer should be applied. Repeat
at 8 to 10 week intervals until
early September. For all succeed-
ing years, three applications of 1/3
lb. of mixed fertilizer per applica-
tion the first in late February or
early March, the second just after
the canes have been removed after

harvest, and the third in late
August or early September are
Excessive amounts of fertilizer
increases the cost of production
and may do more harm than good.
Fertilizing will not offset a poor
stand of plants, imperfect drain-
age, inadequate pollination and
other limiting factors; it should ac-
company other good cultural prac-
tices. The complete effect of a
fertilizer does not appear the year
it is applied since canes produced
one year bear fruit the following
Irrigation. Because of varia-
tions in frequency and amount of
rainfall, irrigation appears neces-
sary for successful blackberry pro-
duction in Florida. How much
water to apply depends on root
zone depth, soil water-holding ca-
pacity and the amount of water
to be replaced at each irrigation
interval. In general, 1 to 2 inches
of water per application is suf-
Irrigation is needed soon after
planting and during the dry peri-
ods of late spring and early sum-
mer. The rate of water use
increases as daily mean tempera-
ture and length of day increase.
During the blossom period, irri-
gation should be done in late after-
noon when bees are not active as
pollinators. During the fruiting
season, irrigate each block immedi-
ately after picking so ripe fruit is
not damaged by falling droplets of
water. Plan irrigation for a week
or so before the first harvest so
subsequent applications fall imme-
diately after picking as water may
soften berries and cause rot.

Figure 3. The difference in size of berries may be due to frost damage,
imperfect pollination, or the fruiting habit of blackberries.


A blackberry is composed of
many drupelets, each of which de-
velops from a single pistil. To ob-
tain a perfect, well-formed berry
most of the pistils must be effec-
tively pollinated. 'Brazos' does not
require cross-pollination; however,
the varieties 'Oklawaha' and 'Flor-
dagrand' do not set any fruit from
their own pollen but produce well-
formed berries when cross-polli-

nated by each other. While the
blossom periods for these two va-
rieties do not fully coincide, they
do overlap during the times of
maximum bloom (Figure 1).
'Oklawaha' and 'Flordagrand'
bloom much earlier than the 'Bra-
zos' variety. The earlier bloom re-
sults in an earlier crop, which is
an advantage for the fresh-fruit

market. On the same site, the trail-
ing and upright types seldom
overlap in bloom, and picking of
'Oklawaha' and 'Flordagrand' may

be in progress before the peak of
bloom occurs on 'Brazos.' The later
bloom of 'Brazos' enables this va-
riety to escape frost damage.

Harvesting and Marketing

The harvest season for 'Okla-
waha' and 'Flordagrand' occurs in
April and May, varying in different
years and with various locations,
and lasts approximately one
month. 'Brazos' ripens later, thus
prolonging the harvest season in
a given area (Figure 2).
Blackberry fruits bruise easily
and are extremely perishable. They
should be handled with care when
harvesting and marketed immedi-
There are two types of markets
for blackberries: fresh fruit and
processing. The fresh fruit outlet
may be divided into distant, home
or local markets and pick-your-
own operations. Until methods are
developed to insure that high qual-
ity fruit will arrive at distant mar-
kets in good condition, local mar-
kets and pick-your-own operations
will continue to be the major out-
lets. The local market has marked
advantages for a grower. The fruit

can be picked at the best stage for
eating and may be marketed
quickly and economically. A loca-
tion near high population centers
on good roads is desirable for road-
side markets and pick-your-own
operations. Operations whereby
customers do their own picking
offer the greatest and most im-
mediate solution to marketing
small units. This method offers the
happiest harvest labor force and a
type of outdoor recreation. In ad-
dition, grading and handling oper-
ations are eliminated.
Increases of both total acreage
and individual planting are needed
for a stabilized processing market.
Labor is both difficult to get and
expensive. Mechanization of grow-
ing, harvesting, and handling
blackberries must be developed to
reduce hand labor requirements.
Mechanical harvesting of Florida
blackberries is still in the develop-
mental stage.


Several kinds of insects includ-
ing thrips, spider mites, caterpil-
lars, stink bugs and beetles may
attack blackberries. Thrips are
tiny insects that infest blossoms
and berries. Injury to fruit has
been attributed to their feeding
and their presence is objectionable
on harvested berries. Spider mites
sometimes become numerous, espe-

cially during dry weather. They
infest the underside of leaves
where they suck out the juices.
Caterpillars that feed on foliage
and others that make a web and
feed on fruit have been occasional
problems. Beetles of different kinds
may feed on leaves, stems and
blossoms; and stink bugs may be-
come a problem on berries.

Control measures for insects
have not been needed in some
areas, while in other areas a regu-
lar spray program appears to be
desirable. The application of mala-
thion at weekly intervals begin-
ning just as the plants flush
out in the spring and continued
through harvest has given satis-
factory control of most insect and
mite pests. Apply malathion at
the rate of 1 quart of 57% emul-
sifiable concentrate or 4 pounds
of 25% wettable powder per 100
gallons of water. For 1 gallon of
water, use 2 teaspoons of 57%
emulsifiable concentrate or 4 table-
spoons of 25% wettable powder.
Use only the emulsifiable concen-
trate near harvest to avoid visible
residues on harvested berries by

wettable powder. Do not apply
malathion within 1 day of harvest.
Bees may be poisoned if spraying
is done during bloom, while they
are working the flowers. This re-
duces the amount of cross-polli-
nation and results in poor fruit
Where a regular spray program
is not needed and insect problems
develop, malathion can be used for
thrips; Kelthane for spider mites;
Sevin, DDT or TDE for caterpil-
lars; Sevin, DDT or malathion for
stink bugs; Sevin or DDT for
beetles. Do not apply Kelthane
within 2 days, Sevin within 7 days
or TDE within 14 days of harvest.
Do not apply DDT when fruit is


Fungus diseases appear com-
monly on blackberry plants grown
in Florida. Leaf Spot appears on
the foliage as dark red spots with
a whitish center. It occurs in most
blackberry plantings and tends to
weaken the plants. Good cultural
care, including cutting back both
old and new canes to ground level
after harvest (burning all pruned-
off parts), tends to offset any ex-
haustive effect from this fungus.
Spraying with a fungicide will as-
sist in controlling this disease.
Anthracnose lesions appear as
grayish spots with a purplish
brown margin on both canes and
fruit stems, causing some deform-
ing, browning, and withering of
the berries. The same cultural
practices as with leaf spot lessen
the weakening effect of anthrac-

Rosette or Double Blossom can
cause heavy damage to 'Brazos'
plants in Florida whereas the trail-
ing varieties are highly resistant.
A mildly infected 'Brazos' planting
usually produces a high yield, but
as the infection becomes severe,
vigor and yield decline severely.
Rosette is readily recognized at
two stages: (1) an abnormal flow-
ering stage; (2) witches'-broom
stage in which multiple, bunchy
shoots appear on semi-dormant
canes. Flowers on infected shoots
are often more numerous than
usual and may be elongated with
the sepals extending as leaflike
structures. Petals may be deep
pink, and twisted, and the pistils
often die before the petals open.
The disease follows a set cycle.
In spring, spores produced on the
blossoms infect young buds on new

canes and later the flower buds. In
winter and early spring infected
buds show abnormal flowers and
witches'-broom. Spores produced
on the stamens and pistils infect
young buds of the new canes. Se-
verely infected canes show rosette.
Cutting back to ground level and
burning both the old and new canes
soon after harvest is a good prac-
tice, and appears to prevent seri-
ous infection in some plantings.
There is not enough experimental
evidence at present for a definite
recommended spray program.
In the past few years, several
fungi have caused considerable
damage as Berry Rots in black-
berry plantings. These rots appear
on the berries as a white or grey
mold growth, either in the field or
after harvest. As the rots develop,
the fruits break down, becoming
soft and watery.

Several fungicides may be used
to control the various fungus dis-
eases of blackberries. For the leaf
spots and anthracnose, copper, zi-
neb, or maneb may be used effec-
tively. During the fruiting period,
copper or captain may be used for
berry rot control. A regular spray
program is best, but it is not al-
ways needed, especially in small
Dosages for the fungicides men-
tioned are: Copper 48-53%, 3 lbs.
per 100 gallons of water (11/ table-
spoons per gal.); maneb 80%, 11/2
lbs. per 100 gallons (3/4 table-
spoons per gal.) ; maneb 80%, 1l
per 100 gallons (11/3 tablespoons
per gal.); and captain 50%, 4 lbs.
per 100 gallons (3 tablespoons per
gal.). Do not use maneb after
bloom period, or zineb in less than
14 days of harvest. Captan and
copper may be used during
harvest period.

Figure 4. Witches'-broom and abnormal blossoms
with a normal, healthy blossom in the center.

caused by Rosette





0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60

Days of Blossom

Diagram 1.

The average length of blossom period for each of 3 black-
berry varieties and their relationship to each other.




0 4 8 12 16 20 24 28 32 36 40 44 48 52 56

Days of Harvest

Diagram 2.

The average length of harvest period for each of 3 black-
berry varieties and their relationship to each other.