Skip to main content

Downy Mildew of Cucurbits

Updated July 2020

This is one of the most common and destructive diseases affecting all cucurbit crops in the eastern United States including New York. Occurrence varies spatially and temporally year to year with movement of this wind-dispersed pathogen. There are some resistant cucumber varieties. Fungicides are the main management practice.

Listen to Meg McGrath talk about managing downy mildew in a teleconference hosted by Steve Bogash of Marrone Bio Innovations on 17 June 2020. Dial 515-604-9875. At prompts enter 832191 for access code and 9 for reference number.

Detailed information about downy mildew and its management are in the following articles and tables:


cucumber leaf with downy mildew

Symptoms of downy mildew on upper surfaces of cucumber leaves. Leaf in the center is the leaf in the second image.

close-up of cucumber leaf with downy mildew

Symptoms of downy mildew lower surface of cucumber leaf. Pathogen sporulation is below the yellow and brown symptoms visible on the upper surface (first image).

© 2020 Cornell University. This web resource is designed to enhance access to Cornell's vegetable production resources. This site is a project of the Cornell Vegetable Program Work Team (PWT). Visit the About section for more information on the team. Comments or questions? Email Craig Cramer, Communication Specialist, School of Integrative Plant Science. Some of the informational links provided are not maintained by, nor are the responsibility of, Cornell Cooperative Extension and Cornell University. Mention of commercial products and trade names is for educational and informational purposes only. Manufacturers' instructions change. Read the manufacturers' instructions on the pesticide label carefully before use. Inclusion of information is not intended as an endorsement by Cornell Cooperative Extension or Cornell University, nor is discrimination of excluded information implied. Cornell University is an equal opportunity, affirmative action educator and employer. If you have a disability and are having trouble accessing information on this website or need materials in an alternate format, contact for assistance.
Skip to toolbar