the Economic Products of India.
Diseases of the Poppy Plant.
53
PAPAVER
somniferum.
CULTIVATION
Diseases.
sons. The symptoms are a general drying up of the upper or younger
parts of the plant, the leaves becoming shrivelled and variously contort--
ed, with the veins of a brownish or purple-black colour, while a longitudi--
nal section of the plant shows a dry and shrivelled apex, and the pith less
or more decayed from above downwards. As showing that this injury is
caused purely by heat, it is frequently observed that the stem throws off
lateral shoots immediately after irrigation.
(c) Sclerosis.—The symptoms of this affection, says Mr. Scott, are a
gradual drying and hardening of the whole tissues of the plant; it is evi--
dently a constitutional disease. It appears to be rather a prevalent form
and occurs indifferently in crops on irrigated and unirrigated lands, on dry
and poor soils, as well as on those which lack neither manurial conditions
nor moisture. It would appear to be due to a partial arrestment of the
vegetative functions as the plant attains the flowering stage. The first
symptom of it is ordinarily the slight persistence of the sepals, imperfect
expansion of the petals, and less or more complete persistence of the
stamens which are often found even in the ripe capsule as a fringe around
its base. The capsules are generally of a small size, and very nu--
merous (from 12 to 20, or 30 on each plant) and rarely yield the drug to
more than two incisions and even that scantily. Where prevalent it thus
seriously damages the crop. Mr. Scott found there was a strong tendency
for this disease to become hereditary. It thus becomes necessary that the
cultivators should be taught to avoid collecting seed from such diseased
stock.
Sclerosis.
(d) Petechia.—In this disease the cuticle of the leaves becomes more
or less densely covered with specks or spots, somewhat resembling those
caused by the bite of insects. In moist weather plants thus affected are far
from uncommon in our poppy-fields. The first sign of the disease is
shown by the leaves acquiring a pale, dull, yellowish-green tinge, and soon
after the whole surface becomes studded with specks and patches of purply
-black. The affection is much less developed on the lower than on the upper
surface of the leaf; the latter ultimately acquires a nearly uniform purply
-black colour. The discoloration is mainly confined to the leaves, and very
rarely accompanied by any external exudations from the tissues, though
all parts of the plants are soft and juicy; indeed, in a quasi-dropsical con-
-dition. In many cases this disease seems largely attributable to over--
crowding of the plants.
(e) Gangrene.—The soft herbaceous parts of the plant are most affected
by this disease. It frequently breaks out on injured parts of the plant but
is more or less local. But when due to an excess of moisture and low
temperature, the whole plant may be affected. Indeed, cold and damp
seem frequent causes of this disease. The affected parts are, Mr. Scott
says, easily recognised by their curved or depressed shoots and drooping
and even revolute leaves. The flowers expand imperfectly and the stamens
are always more or less persistent, forming a shrivelled fringe around the
base of the capsule. The latter is also very generally arrested in an early
stage of its growth, and very rarely are the seeds perfected. As the disease
progresses, the stems, leaves, and capsules are spotted with black resiny
exudations. If healthy plants are inoculated with this disease, it spreads
upwards from the point of inoculation. G a n g r e n e
.
2nd, Injuries Caused by Parasites. —These have been already explained.
Mr. Scott refers to two sections, the higher flowering parasitic plant and the
lower or flowerless plants—fungi. Of the former he noted two members of
the same genus - Orobanche indica and O. cernua —the broom-rapes These
occur parasitically on a great many other plants, such as tobacco, brinjal,
rape, and mustard; indeed, the last-mentioned species affects the tobacco ( ) P a r a s i t i c f l o w e r i n g P l a n t s
.
Petechia.