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
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
Subtropical ExperimeFnt Staton
Route 2, Box 508
Mimeographed Report No. 16 -anueri '
University of Florida
SUB-TROPICAL EXPZRIMETT STATION
TEI TROPICAL BLACK P PASPB3TRY
R. Bruce Ledin
Rubus albescens Roxb. (Rubus lasiocarpus Smith), the Mysore or tropical black
raspberry, is native to the mountains of India, Burma end Ceylon, growing at an
altitude of 1500 to 10,000 feet,
DFSC.IPTION. The young stems are gleucous and possess straight or hooked sharp
prickles. The leaves have 5 to 9 toothed and prominently veined leaflets which
are dark green in color and glabrous above but with white matted hairs on the
lower surface; the rachis, petiole, and midrib of the leaflets have curved
prickles. The flowers are 3/8 to 1/2 inch in diameter and are produced in clus-
ters of 8 or more at ends, or in the exils of the leaves, on the young lateral
shoots near the tips of the cenes. The sepals pre 5, persisting at the base of
the fruit, and are as long as the petals; the petals are 5, a purplish-pink in
color; the stamens are numerous and form a ring around the base of the recepta-
cles; the carpels are numerous and are arranged on a conical receptacle in the
center of the flower, the tuft of styles are reddish in color. The compound
fruit is 1/2 to 3/4 inch in diameter and consists of numerous segments which are
red or orange-red at first but on reaching maturity become a dark purple color.
The plants have a typical raspberry-like growth, producing several shoots called
canes from the roots. These canes will grow 10 to 15 feet during the summer
months, and when pruned properly, the short lateral branches are produced which
bear the flowers end fruits during the winter end spring. The flowers will begin
to appear in early December end the fruits will first appear in late December;
flowering and fruiting will continue on into the spring and early summer months,
the peak being reached in March and April.
The fruit of this black raspberry is juicy, mildly pleasant, slightly sweet, with
the flavor being, perhaps, a little on the flat side.
CULTUPJ. There are many problems still to be solved in growing this plant in
Florida. We do not know how many years the plent will live, we do not know much
about its diseases and pests, or much about the pruning schedule. The cultivation
of raspberries in the north is rather well known; the plants go through a dormant
period in the winter and the pruning schedule has been well worked out. Our plants
grow the year around, making rapid growth in the summer months. :uch study is
needed in order to determine the best time end the number of times the plants
must be pruned in order to bring about the maximum yield. The remarks that are
given below are more or less tentative and probably will be changed as we learn
more about the growing of the raspberry in Florida.
- 2 -
PROPAGATION. 1) Seed. The seeds take several weeks to sprout and are subject
to damping off. To control the damping off, dust the seeds with Spergon and plant
them in a mixture of peatmoss and vermiculite. The fresher the seed, the better
and quicker the germination. If the seeds are not to be planted immediately, they
should be stored in the refrigerator. Then the seedlings become about 3 inches
tall, transplant them into individual pots or cans. It will take approximately
10 months before the plants are large enough to be set out in the field.
2) Tip layering. This is best done in the late summer after the fruiting season
is over and the plants are growing vigorously. The long arching cenes are bent
down to the ground or into cans or pots, and the tip is then buried with soil to
a depth of 1 or 2 inches. The tips will root in 2 to 3 weeks, thus forming new
plants. The old canes are then severed just back of the rooted portion.
PLANTING. The young plants are set out in rows, the rows and the plants can be
from 4 to 6 feet apart. The plants should be at least 12 inches high when set
out. If larger plants are purchased from a nursery, it will be necessary to cut
back all the canes to 6 inches or less in height--leaving stumps or "handles"
which will develop the new shoots. The best time to plant is in the spring or
summer, but the plants can be set out at any time of the year as long as they are
watered and taken care of.
SOIL. The tropical black raspberry will grow in the rocky alkaline soil of south-
ern Florida, as well as in the acid sends that prevail over most of the state.
The plants will grow best in a relatively rich soil, a sandy loam being preferred.
If the soil is too sendy, add humus or compost material; if the soil is marly, add
sand and compost material to loosen it up. It is not recommended that the plants
be planted in the marly soil of the glades, the muck soil of the Everglades, or in
low places in the sandy areas north of Miami. These soils are subject to flooding
in the summer and the raspberry will not grow in wet soil. It is important that
the soil has good drainage the year around.
PREPARATION OF THE SOIL. The soil should be cultivated to a depth of 4 to 6
inches before the plants are set out. In the rocky soil of Dade County, it is
advisable that compost material be added to the holes that are prepared before
the plants are set in.
CULTIVATION. The plants are shallow rooted so it is not advisable to cultivate
the soil very deeply. The weeds should be kept down between the rows, as well as
around the plants. The plants require a good supply of water, especially during
the dry winter months. For a large planting, an overhead irrigation system is
probably the best.
MULCHING. Apply a heavy mulch around the plants--the mulch may be straw, hay,
leaves, wood shavings, or any similar material. A heavy mulch will keep the
weeds down and will help to conserve the moisture in the soil.
FERTILIZER. A well balanced fertilizer should be applied twice a month until the
plants have obtained a good growth; thereafter an application of once a. month
should be sufficient. About pound of fertilizer per plant--two handfuls--appliedi
around each plant should be enough, A 4-7-5 fertilizer has been used with success.
NUTRITIONAL SPRAY. If the leaves become yellow and appear chlorotic, spray the
plants with a nutritional spray containing zinc, copper, manganese, and lime.
SUPPORT. Some sort of support is necessary to hold the canes upright. A two-
wire trellis should be sufficient. The two wires mey be placed one above the
other--the first wire about 2 to 3 feet from the ground and. the second wire 2 to
3 feet above the first--or the two wires can be placed parellel to each other at
a height of 5 feet, one wire on each side of the row. Steel posts should be placed
at both ends of the row and within the row a post every 10 feet should be suffi-
cient; the wires are then attached to these posts. The canes are tied to the wires
PRUNING. The fruit is produced on young lateral branches; the best and largest
fruit being produced on the thickest canes that produce the laterals. One of the
main purposes of pruning is to produce long woody canes that bear lateral branches,
which in turn produce secondary laterals on which the fruit is produced. The
plants in Florida are continuous growers and during the summer months produce a
vigorous growth. The pruning schedule to develop the right kind of branches is
one which still has to be worked out. The schedule given below is a tentative
1) After the canes have finished fruiting in late spring or early summer,
these old canes must be cut off to the ground. Also, at this time, all
dead wood should be cut out and a certain amount of thinning should be
done so that 4 to 6 new canes per plant are left, being sure that the
most vigorous and healthiest shoots are selected. All the material thus
trimmed should be burned.
2) These new canes are allowed to grow during the summer and they should grow
rapidly and produce a. heavy growth if the plants are well mulched, watered,
and fertilized. Toward the end of the summer (August to September) these
canes should be cut back to 5 feet; this will force the lateral branches
3) In November the lateral branches should be cut back to about 8 or 10 in-
ches; this will force the secondary laterals to develop. At this time,
all dead wood should be again cut out and the canes thinned to about 5
per plant, selecting the most healthy shoots. All trimmed material should
DISEASES AND PESTS. 1) Red spider. This insect has been observed infesting the
seedlings. Sulfur dust hes been used successfully in controlling rod spider with-
out damage to the plants.
2) Anthracnosc or cane spot. Fungus infection of old canes is almost universal
in raspberries. The best method of control is to keep the area clean around the
plants and by burning all the trimmed material, especially the old canes that have
already produced fruit.