Vegetable Disease Updates: August 30, 2017

Within the past week, there have been three separate reports of downy mildew on jack-o-lantern pumpkin in eastern Virginia.
Vegetable Disease Updates: August 30, 2017 - Articles

Updated: October 12, 2017

Vegetable Disease Updates: August 30, 2017

Downy mildew on pumpkin. Photo: Beth K. Gugino, Penn State

These closer sources will put pumpkin crops more at risk especially if the forecasted rainy weather originates from movement up the east coast. Depending on how close you are to harvest, you may want to consider including a downy mildew specific fungicide in your pumpkin fungicide program although protectant fungicides will also help protect where they are applied. Downy mildew will not directly infect the pumpkin fruit but rather will reduce fruit quality through poor ripening or sunscald as a result of a reduced foliar canopy. If your leaves are already down then including a downy mildew specific fungicide is not necessary. However consider making one more application for powdery mildew to protect the handles which are now more exposed to maintain the integrity of the handles post-harvest.

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. The forecasted risk maps are also based on knowing where there are downy mildew infected fields (sources of the pathogen) so it is important if you suspect downy mildew on your farm contact by email at or by phone at 814-865-7328 or contact your local Penn State Extension Office.

Late Blight: Still a Concern

Although much of the early season potato crop is done for the season, late blight continues to remain a concern in late season tomatoes and potatoes. So far this season it has been confirmed in Chester, Indiana and Cumberland Co., PA. It is currently suspected but has not been confirmed on tomato in Mercer and Erie Co., PA and we were unable to confirm that the symptoms observed on the Lehigh Co. tomato sample were due to late blight. This is why sending samples in for confirmation is important and although pictures can be an important diagnostic tool, they are not a substitute for looking at an actual sample. The evening/night temperatures and dew periods continue to be favorable for late blight so please continue scouting - the season is not over just yet!

If you suspect late blight on your farm, please contact your local Penn State Extension Office or via email or by phone at 814-865-7328. We are interested in collecting samples so we can better understand how the pathogen population is changing both within and across growing seasons. Also for the information regarding where the latest confirmed outbreaks have been reported and to receive email or text alerts about when late blight has been confirmed with a personally defined radius from your location visit USBlight.org.

Authors

Integrated vegetable disease management Plant pathogen diagnosis Disease monitoring and forecasting Sustainable crop production

More by Beth K. Gugino, Ph.D.