Cucurbit Downy Mildew Update for Pennsylvania

Posted: September 10, 2014

To date, downy mildew has only been confirmed on cucumber in PA. Since downy mildew does not affect the fruit, as fruit reaches maturity, the management of this disease can become less a priority.

Despite the numerous earlier outbreaks of downy mildew on multiple hosts in adjacent states to the south and west, downy mildew has only been confirmed on cucumber in Centre, Lancaster, York, and most recently in Washington Co. Current weather patterns the past few days have been most favorable for disease development and spread in the lower southern tier part of the state in Chester, Lancaster, York, Adams and Franklin Counties and the rest of the mid-Atlantic region.

Since downy mildew does not directly affect the fruit, as we get closer to harvest and the fruit are fully mature, managing the disease becomes less important. It is primarily a concern earlier in the season because it reduces the photosynthetic capacity of the plant which leads to lower fruit quality and an inability of the plant to ripen the fruit. Defoliation can saw lead to sunscald if the fruit have not fully matured.

If you suspect downy mildew on your farm to let me know either by email at or by phone at 814-865-7328 or contact your local Penn State Cooperative Extension Office. For the latest information on outbreaks and to receive email or text alerts please visit the Cucurbit Downy Mildew Forecasting website ( Updates will also be made to the 1-800-PENN-IPM hotline weekly or more frequently if needed to provide growers with information that can be used to help make timely management decisions.

Contact Information

Beth K. Gugino
  • Associate Professor Vegetable Pathology
Phone: 814-865-7328