PRESS BULLETIN No. 316


UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION

EGGPLANT DISEASES AND THEIR CONTROL
By C. D. SHERBAKOFF
Growing of eggplants is often rendered unprofitable on ac-
count of certain diseases affecting this crop. Its more important
diseases have been studied and much positive information has
been obtained. During the past several years while with the
Florida Experiment Station the writer has been conducting some
experiments and field observations with these diseases, and ob-
tained some additional information. The following is a brief
summary of our present knowledge of some of the most import-
ant diseases.
DAMPING-OFF: The disease is a decay of the basal part
of the stems of young plants. The disease often produces an
effect as if the plants were scalded with hot water. The damage
caused by damping off depends to a great extent on the dampness
of the air, hence the name. A great many plants are subject to
this trouble, and in all known instances it has been found to be
caused by certain fungi, mostly either by Rhizoctonia solani,
Pythium debaryanum, or by some of the Fusaria. In the case of
eggplant, the fungus Phomopsis vexans has also been found to
cause damping-off. When older plants with hardened, woody
stems are attacked, the result is merely a scar on the stem. How-
ever, such plants should never be used for transplanting as they
may introduce some very important diseases into a field. To con-
trol damping off: (1) Use seed extracted from healthy fruit and
under sanitary conditions; (2) seed-bed soil should be either new
or sterilized; (3) avoid the use of organic fertilizers in the upper
2 inches of the seed-bed soil; (4) do not grow plants too thick in
the seed bed; (5) give the plants as much air and sunshine as
possible; (6) sow the seed in rows and cultivate the seed bed
often.
BACTERIAL BLIGHT: This disease is characterized first
by a sudden wilting of the plant tip or of a single leaf near the
top; and second, by a quick withering and dying of the entire
plant. When the stem of a diseased plant is cut across it shows
browning of its woody elements and an exudation of a dirty-
white, puss-like substance consisting of the causal bacteria, Ba-
cillus solanacearum. Proper crop rotation is at present the only


December 13, 1919






known method of control of this disease. Fields infected with
the bacteria should not be planted to eggplant, nor to the Irish
potato or tomato, which are also subject to this trouble. To
check rapid spread of the disease in the field, the destruction of
the affected plants as soon as they are detected is strongly recom-
mended; also keep insects in check.
TIPOVER OR FALLOVER: Sometimes the stems of ap-
parently healthy eggplants break near the ground and the plants
tip or fall over. It has been suggested that a strong wind was
the cause of the trouble. However, the writer finds that the
trouble is due to the fungus Phomopsis vexans. The disease is
sometimes responsible for a considerable loss of plants in the
field. To control tipover, secure seed from healthy fruit and
under sanitary condition; the seed-bed soil should either be new
or should be properly disinfected; do not plant eggplants in
a field which has previously been affected with the disease.
STEM-ROT is a dry rot of the stem near or at the level
of the ground. Plants affected with it usually fail to-produce
any good fruit. The cause and control are the same as for tip-
over,
FRUIT ROT appears in the form of somewhat sunken,
pale spots, which in time become dotted with minute pimple-like
postules, fruiting bodies of the causal fungus Phomopsis vexans.
Ordinarily, the rot spreads very rapidly and in a few days in-
volves the entire fruit. The total damage from the trouble is
often such as to make growing of eggplants quite unprofitable.
To control fruit rot, do as suggested for tipover, and in addition,
spray thoroly with 5-5-50 Bordeaux mixture. Repeat the spray-
ing every ten days until about a week before the last picking.
To prevent conspicuous staining by Bordeaux, this mixture may
be substituted by ammoniacal solution of copper carbonate.
LEAF-SPOT, caused by Phomopsis vexans: These are
irregular, brown spots without any distinct markings or
zonations, but often with darker specks, the fruiting bodies of
the causal fungus. Control is the same as that for tipover and
fruit rot.
LEAF AND FRUIT SPOT, caused by the fungus Alter-
naria sp.: The leaf spot is brown, and usually shows some zona-
tion. The fruit spot is brown, hard, zonated, not sunken. Neither
of these troubles is, so far as it is known at present, very
important. Spraying with 5-5-50 Bordeaux mixture should con-
trol them.
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