Colorado Pf.ant Diseases 
59 
Downy Mildew (Plasmopara cubensis) — Downy mildew affects 
not only the cucuniber but all members of the Cucumber family such 
as cantaloupes, watermelson, squash and pumpkins. AfPected leaves 
show ii'regular yellow spots often covering an entire leaf in whibh 
case the leaf shrivels and dies. The oldest leaves are first affected, 
spreading towards the ends of the vine. A whitish downy fungus 
groAvth tinged Avith purple is often seen on the under side of the leaf. 
The few cucumbers formed are small and misshapen. Large numbers 
of spores are formed on the fungus growth, Avhich serve to spread 
the disease. 
Downy inildeAV may be held in check by spraying with Bordeaux 
mixture (5-5-50). The first application should be made as soon as the 
vines begin to run. Later applications should be given at ten day 
inteiwals. 
Bacterial wilt of cucurbits on squash. 
