Many growers used foliar fungicides on soybeans in 2005, and there were many anecdotal reports of yield gains. The reports of yield gains have piqued grower interest in foliar fungicides, and many will consider trying foliar fungicides in 2006.
However, a word of caution must be offered about these anecdotal reports. We often hear about the positive responses from the latest input, but what about all of the neutral or negative yield responses?
The bottom line: Foliar fungicides potentially provide an opportunity to increase soybean yield through protection from plant diseases, increases in plant growth efficiencies and increases in stress tolerance under some conditions.
Work is underway (and more is planned) to understand when and where economically positive benefits from foliar fungicide use on soybeans are most likely to occur.
Unfortunately, the inconsistent results from fungicide trials make it difficult to successfully implement a foliar fungicide program that reliably improves yields in Minnesota.
Even with the threat of Asian soybean rust, the inconsistency of soybean yield response to foliar fungicides makes their use an economically risky proposition.
More details are available at www.extension.umn.edu/cropenews.
By Ryan Miller, regional educator, crops and Dean Malvick, plant pathologist at the University of Minnesota Extension Service