Share

Downy Mildew on Cantaloupe

Posted: August 7, 2012

Yesterday, downy mildew was confirmed on cantaloupe in our downy mildew sentinel plot in Lancaster Co.
Downy mildew lesions on the lower leaf surface of cantaloupe in the early morning. The observation of purplish-gray sporulation on the underside of the leaf is necessary for diagnostic confirmation. (Photo: Beth K. Gugino)

Downy mildew lesions on the lower leaf surface of cantaloupe in the early morning. The observation of purplish-gray sporulation on the underside of the leaf is necessary for diagnostic confirmation. (Photo: Beth K. Gugino)

This is the first confirmed report of downy mildew on cantaloupe in PA however it has previously been reported on this host in Ohio, New Jersey, Delaware and in regions further south. Downy mildew continues to be widespread on cucumber across the state. Conditions were very favorable for disease spread over the weekend. Symptoms resulting from infection over the weekend could be visible as soon as today or over the upcoming several days. The drier conditions over the past couple of days have less favorable for disease spread.
   
If you have downy mildew in a cucumber field that you are no longer harvesting, it is recommended that you vine kill or disk in the field to reduce the spread of the pathogen to neighboring farms. Since the downy mildew pathogen requires living host plant material to survive, once the plant tissue is dead so the pathogen.

If you suspect downy mildew please contact your local Penn State Extension office and/or send me a sample (overnight delivery) for confirmation to Beth Gugino, Department of Plant Pathology, 219 Buckhout Lab, University Park, PA 16802. We will examine the sample under a microscope and look for the characteristic downy mildew spores. Please visit the Cucurbit Downy Mildew Forecasting website (http://cdm.ipmpipe.org/index.php) for the latest list of disease outbreak locations and forecasts. This information is updated by the end of the day on Monday, Wednesday and Fridays.