Bulletin 214, Cotton Diseases in Florida


rotted before reaching the surface. The spots on the cotyledons
are dead areas of irregular outline and are of less importance than
the damping-off, though they may spread to involve the whole
top of the seedling, which is thus killed. The lesions on the stems
and leaves of large plants are not a serious manifestation of the
disease and usually follow the attacks of the bacterial blight or-
ganism. The most injurious manifestation of anthracnose occurs
on the bolls, where the symptoms vary somewhat, depending on
the time and nature of the infection. Infection may take place
through the dead pistils of the flowers, in which case the entire
contents of the boll may be rotted with but minor external evi-
dences of disease at the tip of the boll. The most commonly de-
scribed type of anthracnose injury follows infection on the side
of the boll with or without the aid of injuries to the surface of the
boll from other causes. Infection often also occurs along the lines
of dehiscence of the boll. Following penetration of the boll, brown-
ish spots are formed which are somewhat sunken and surrounded
by a reddish border. The spots may enlarge under favorable con-
ditions to involve half of the boll, and by the coalescence of a
number of spots the whole boll may be destroyed. The centers of
the spots become covered with the orange-pink, slimy masses of
spores during wet weather, but may be gray and very similar in
appearance to bacterial blight lesions in dry weather.
 When the infection occurs in young, succulent bolls a general rot
often occurs and the lint and seed become dark brown and dry


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Fig. 9.-Bolls showing different degrees of anthracnose injury.