Applying fungicides to soybeans free of foliar disease problems isn't likely to help alleviate drought stress and could contribute to fungicide-resistant diseases, says a Purdue Extension plant pathologist.
Soybean growers probably are feeling pressure to apply fung
Applying fungicides to soybeans free of foliar disease problems isn't likely to help alleviate drought stress and could contribute to fungicide-resistant diseases, says a Purdue Extension plant pathologist.
Soybean growers probably are feeling pressure to apply fungicides as the crop enters the R3 growth stage, regardless of disease presence, based on claims that the products can reduce drought stress, increase photosynthesis and, ultimately, increase yields.
But a series of Purdue University research trials has been unable to confirm those claims.
"We've done research on fungicides in the absence of disease for several years now at Purdue. What we've found is that when we don't have disease pressure there - foliar diseases such as frogeye leaf spot or Cercospora leaf blight - we don't often see an economic benefit from a fungicide application," Kiersten Wise said.
"We know that with soybean prices what they are, that benefit would be something to really capitalize on this year. But we just don't see a consistent response, so it makes it very hard to recommend those fungicides in the absence of disease."
Many foliar diseases struggle to develop in hot, dry weather, so this year's excessive heat and drought have kept most at bay in fields that aren't irrigated and haven't had much rainfall.
In addition to the lack of profitability, Wise said applying unnecessary fungicides also could lead to fungicide-resistant diseases. One example is frogeye leaf spot, a major disease of soybea