DISEASES OF CUCUMBERS
 BY G. F. WEBER

 Cucumbers have been profitably grown in Florida for years.
 The quantity of production has steadily increased until at present
 this crop is one of the leading truck crops of the state, returning
 to the growers millions of dollars each year. The plant has been
 successfully cultivated in nearly-every section of the state at
 some season of the year.
 During certain seasons the yields are reduced because of the
 prevalence of diseases. There are a number of these diseases
 attacking the cucumber plant, but it is seldom that more than
 one particular disease is important in a single season.
 This bulletin contains information concerning the diseases
 that may attack the cucumber plant. Their occurrence and sea-
 sonal development are discussed. A detailed description of each
 disease is given, followed by control methods in each case. Certain
 information previously published in Experiment Station Bulle-
 tins 121, 139 and 177 is contained herein.

 DOWNY MILDEW OF CUCUMBERS
 One of the most destructive diseases of cucumbers in Florida,
 commonly called "downy mildew," is caused by the fungus
 Pseudoperonospora cubensis (B. & C.) Rostow. The disease has
 been found in the different countries of the world.
 In the United States the disease has been collected in almost
all of the states east of the Mississippi River; it is scarce in the
western part of the country. It is more serious in the southeast-
ern states than in the northern states. In Florida the disease has
been found in every county and has been collected by the writer
during every month of the year. Between November and March
it is common in the southern counties. During the past several
seasons it has been more destructive than all other cucumber
diseases combined.
 This disease has been known to exist in Florida for the past 40
years and has been a factor in the production of cucumbers during
this time. The disease appears on young plants before the
runners develop but usually not in destructive form until about
picking time. Often the lack of rain accompanied by continued
high temperatures holds it in check. However, under favorable
conditions, the disease will show up on the host plant at any time