Bulletin 208, Cucumber Diseases in Florida


wet with dew. Fungicides are not cures but rather preventive
and should be used accordingly. Begin applications early, repeat
them often, do a thorough job each time and it will be found
profitable.

 ANTHRACNOSE
 The disease known as anthracnose is caused by the fungus
Colletotrichum lagernarium (Pass.) Ell. & Hals. This disease
has been known to occur on the cucumber for more than half a
century and has been found in both Europe and America. In the
United States the disease has been reported most common in the
states east of the Mississippi River and rare in the western
states. In Florida the disease is common and often severe. It
has been found almost everywhere the host plant is grown and
has been known to the growers since the early cultivation of the
plant. The same fungus causes anthracnose of muskmelons,
watermelons and some varieties of gourds.
 The disease is favored by high temperature and high humidity,
heavy dews being the most important factor in Florida. It has
caused considerable losses in Florida in certain localities where
the growing of cucumbers is concentrated. The fall crop of
cucumbers, as a rule, suffers more from this disease than the
spring crop. It has been observed that cucumbers planted in the
fall in old watermelon fields Were total losses due to the fungus
spreading to the cucumbers from the old infected melon vines and
fruit. The fungus will spread from watermelons to watermelons,
cucumbers, cantaloupes and gourds and from each of these hosts
to the others.
 The fungus lives during the growing season on the numerous
 host plants and when they die it remains in the old vines and
 fruits left in the fields. The climate of Florida is such that the
 fungus easily lives the year around and when a new crop is
 planted, if weather conditions are favorable, the first leaves in-
 variably become infected.
 Ten days to two weeks are required for the fungus to produce
 dead areas in the leaves, although some yellowing is often visible
 after one week. (Fig. 7.) Because of this early infection first
 signs of the disease may be observed on the leaves in the immedi-
 ate vicinity of the hill. These infected leaves produce the spores
 for general infection of the crop later in the season. It is at this
 time that the grower begins to find that the disease is giving him
 trouble.