Downy Mildew of Cucurbits

Pseudoperonospora cubensis


A fungal disease that causes yellow spots about 15 mm diameter on the upper surfaces of leaves. On the underside of the leaf opposite each spot, furry slightly purple hyphal growth appears. The spots to be somewhat circular on Rockmelon and more angular on other species. Leaves with many spots will wither and die.

Species Affected:

Apple cucumbers are susceptible. Early Marketer and Dasher have some tolerance.
Rockmelons are susceptible. Gulf Coast has some tolerance.
Pumpkins and Squashes tend t be only severely affected in abnormally wet conditions


Favoured by warm moist conditions.
Spores are spread by wind.

Life Cycle:

Origin and History:



Management and Control:

Plant tolerant varieties.
Remove and destroy infected leaves and old plants.
Apply fungicides.

Related and Similar Species:


(McMaugh, 1985)


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