"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
For the complete NCR-25 Report, Gray Leaf Spot of Corn: An Update, visit the home page of the American Phytopathological Society (APS) at http://www.scisoc.org. 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.