Bulletin 208, Cucumber Diseases in Florida


 The organism causing this disease (on leaf and fruit) has been
found on a large number of the commercial varieties of cucum-
bers, and several species of gourd which are closely related to the
cucumber. To judge from observations made in Florida the dis-
ease is favored in its spread and destructiveness by cool, rainy
weather. High temperatures tend to check the development of the
disease and during continued periods of warm weather the plants
grow away from the disease. The rain aids in the dissemination
of the organism by washing the bacterial ooze from the infected
areas on the leaves to the ground where it is carried by running
surface water and splashed upon other plants by the rain drops.
 The organism enters the leaves and fruits through the stomata
and results in the formation of the spots that are known to
cucumber growers. Wind, insects and pickers are also carriers
of the organism and are instrumental in the spread of the disease.
The organism is brought into the field primarily with the seed, on
which it will live for a considerable length of time. Since most
of the northern states have
reported the occurrence of
the disease it is logical to
suppose it has come from
that source, as very little
seed is raised in Florida.
 Description: It is impos-
 sible to look at cucumber
 seed and tell whether they
 are infected with the angu-
 lar leaf spot organism.
 When the young plants
 emerge the first indications
 of the disease may be found
 by the appearance of spots
 on the cotyledons of a few
 seedlings. It may be so se-
 vere as to kill the seedlings
 or it may not be serious at
 all except that the infected
 seedlings serve as a source
 of infection for healthy
 plants. The lesions appear Fig. 13. Typical angular leaf spot le-
 plants. sions on cucumber leaves.