By KAREN BINDER
Illinois Correspondent

MORTON, Ill. — John Ackerman stood in his pumpkin field under a crystal clear sky Thursday afternoon in central Illinois, and liked what he saw.

“The vines on my crop are looking mighty vigorous; everything looks good so far,” said Ackerman, whose 30 acres of ornamental pumpkins sit in the middle of Morton, home to Libby’s and its giant pumpkin processing facility.

To Ackerman’s good fortune so far, his crop has not shown signs of downy mildew, a fast-acting disease that has reared its head in the Tazewell County area, said plant pathologist Mohammad Babadoost. The University of Illinois extension fruit and vegetable specialist said evidence of downy mildew’s presence was confirmed earlier last week.

Left untreated, fields can be wiped out. “This is a very destructive disease,” he said. “In about a week to 10 days, it takes over the field and almost all of the leaves will be brown. So we are rushing to release the news.”

Ackerman’s crop this season has shown signs of the lesser-destructive pottery mildew, but is otherwise doing well.

“Advisories like this are good for growers because it’s another way to keep them on top of things,” he said.

For crops with at least two weeks’ growing time left, Babadoost recommends spraying this fungicide combination weekly: Previcur Flex 6SC, Tanus 50WG, Ranman 3.6SC, Revus 2.09SC or Presidio 4SC mixed with chlorothalonil such as Bravo Weather Stik.

Without treatment, the disease likely will infect all vine-growing crops, including cucumber, gourd, muskmelon, pumpkin, squash and watermelon. Processing pumpkins grown for canned pumpkin probably won’t be affected, but the cucumber melon and squash crops would experience losses in yield.

Downy mildew affects leaves only. Symptoms of downy mildew vary with the host and the environmental conditions. The first symptom is usually the appearance of indistinct, pale green areas on the upper leaf surface. The pale green areas soon become yellow in color and angular to irregular in shape, bounded by the leaf veins.

As the disease progresses, the lesions may remain yellow or become brown. During moist weather, the corresponding lower leaf surface is covered with a downy, pale gray to purple mildew. Often an upward leaf curling will occur.

There are about 25,000 acres of pumpkins planted in Illinois and an additional 10,000 acres of other cucurbits such as cucumber, melon, watermelon and squash. It is a $160 million industry for the state, which accounts for about 95 percent of the U.S. processed pumpkin supply.