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College of Food, Agricultural, and Environmental Sciences


Pumpkins Facing Another Year of Diseases

September 10, 2004

COLUMBUS, Ohio — There doesn't seem to be one year where pumpkin growers escape serious disease issues. And this year is no different.

Mac Riedel, an Ohio State University Extension vegetable specialist, said that fruit quality could become an issue due to such diseases as anthracnose, powdery mildew, downy mildew and angular leaf spot — a bacterial disease seen more this year throughout Ohio than in the last decade.

"If growers want to keep up foliage and maintain fruit quality, they should maintain a good spray program," said Riedel. "Fungicides used to control powdery mildew, for example, can also be used to control anthracnose and most other pumpkin diseases. Specialized materials must be added to the crop to help control downy mildew."

Cool temperatures in August and excessive moisture have helped spur the development of various pumpkin diseases. And rains associated from Tropical Depression Frances may help further spawn diseases.

Powdery mildew, which infects vine crops, is common in Ohio and shows up nearly every year on pumpkins, ornamental gourds, cucumbers, melon and squash. It affects the foliage and fruit stems and is characterized by a white, powdery mass of spores. In severe infections, leaves will turn yellow and die and stems and handles on the fruit will turn brown, impacting the overall value of the crop.

Downy mildew, which emerges under wet, cool conditions, affects crop foliage. It is characterized by fuzzy, dark purple to grayish patches on the underside of the leaves. The upper part of the leaves may contain pale yellow or green spots.

"The disease doesn't affect any part of the pumpkin except for the foliage, but by doing so, it exposes the pumpkins to sun scald," said Riedel. "Growers should take steps to find shade for their exposed pumpkins, such as covering up the crop with straw or corn stalks during periods of hot sun."

Anthracnose, a fungal disease brought about by wet conditions in the spring, usually doesn't take hold until later in the growing season — usually before harvest. And some growers are already harvesting their crop, with other varieties on tap to be harvested by the end of September.

"Growers could see some substantial fruit defects from early-season anthracnose," said Riedel.

Despite the disease issues, a good pumpkin harvest is predicted. "We had good fruit set and we've seen some large-sized fruit," said Riedel.

Approximately 5,000 to 6,000 acres of pumpkins are grown in Ohio, generating roughly $25 million a year in revenue in local sales and exports to southern states. Pumpkins rank second in Ohio vegetable crops behind sweet corn.

Candace Pollock
Mac Riedel