ST. Paul, Minn. (May 1, 1998)—Research aimed at monitoring the devastating corn disease, gray leaf spot, indicates development of hybrids with genetic resistance is feasible and when combined with crop rotation, yield losses can be reduced. Conducted by a national network of plant pathologists from universities, USDA-Agricultural Research Service and seed companies, this cooperative effort began in response to the major gray leaf spot epidemic that affected the U.S. Corn Belt nearly two years ago and continues to remain a major threat to corn production.
"The findings are significant for several reasons," says Patrick Lipps, plant pathologist and member of the NCR-25 Committee responsible for the updated information. "We realized that hybrids responded similarly across environments which tells us that hybrids with resistance to local fungal populations will have a resistant reaction at other locations as well. This is key for corn breeders. Using resistant hybrids in combination with crop rotation will definitely restrict yield losses."
Although the fungus which causes this disease, Cercospora zeae-maydis, has been around since 1925, its incidence didn’t accelerate until corn acreage was increasingly placed into conservation tillage during the 1980’s. However, Lipps insists, "Growers should continue to use conservation tillage wherever practical. Unless environmental conditions are extremely favorable for gray leaf spot development, the economic and environmental advantages of conservation tillage clearly outweigh the risk of loss due to the disease."
The NCR-25 committee recommends taking the following steps to minimize disease:
Select newer gray leaf spot resistant hybrids for fields with high gray leaf spot potential
Rotate away from corn for one to two years
Plant more, different crops in rotation with corn
Monitor fields throughout growing season and harvest early if high amounts of disease develop during grain fill
Consider preventative fungicides; the economic benefit of controlling the disease with fungicides in grain production fields is marginal except in high risk areas with significant yield losses annually
The American Phytopathological Society is a professional scientific organization dedicated to the study and control of plant disease with more than 5,000 members worldwide.