Although the cucurbit growing season is winding down, we continue to see new outbreaks of downy mildew. We found downy mildew in pumpkins in our sentinel plot in Fremont, OH (Sandusky County) on Friday, September 12. Yesterday we found the disease in butternut squash in our sentinel plot in Celeryville, OH (Huron County). At this point growers need to decide whether or not fungicide application is a good idea from an economic standpoint. In southern Ohio, frost may occur for some time, so keeping cucurbit foliage protected from downy mildew with fungicides may be a good idea. Downy mildew affects leaves, not fruit, so if pumpkins or winter squash are ripe and curing in the field, it may not be necessary to apply fungicides to control the disease. However, control measures for powdery mildew and other diseases that affect handles or fruit need to continue. See my July 3, 2014 post for fungicide recommendations for downy mildew management.
For more information on cucurbit downy mildew and a map of outbreaks in Ohio and the US, see the Cucurbit Downy Mildew Forecasting website. The map below was captured today.
