What is in this article?:
- Itâ€™s time to make soybean fungicide decisions
- Doubt mild winter increased disease potential
• I am sure some parts of the country probably do have an increased disease risk as a result of the mild winter, but I do not believe Kentucky is among them.
• I do not believe the mild winter of 2011-12 has resulted in greater than normal potential for FPS fungal diseases to occur in Kentucky soybeans.
Doubt mild winter increased disease potential
I simply cannot reconcile how the mild winter might have increased the potential for soybean FPS fungal diseases to occur in Kentucky.
I will concede that the mild winter may have increased the risk of insect-vectored virus diseases, such as bean pod mottle virus (transmitted by bean leaf beetles) and soybean mosaic virus (aphid-transmitted). However, these viruses are not controlled by foliar fungicides.
Of course, the mild winter did favor survival of the soybean rust pathogen in the deep South, but our winter, although mild, was still too cold to allow soybean rust to survive the winter in Kentucky.
In summary, I do not believe the mild winter of 2011-12 has resulted in greater than normal potential for FPS fungal diseases to occur in Kentucky soybeans.
Dry, and now extremely hot and dry, weather across most of the state has kept fungal diseases in check up to now. The soybean crop is very stressed and if some relief does not come soon, yields will be seriously hurt by drought and perhaps charcoal rot and soybean cyst nematode, but not by FPS diseases.
Strobilurin-based fungicides, such as Headline or Quadris, or strobilurin-triazole products, such as Stratego YLD are reported to impart some stress tolerance to treated crops. Nonetheless, it is my experience that stress tolerance benefits are simply overwhelmed when soil moisture is limiting for an extended period of time (e.g., drought).
It is anyone’s guess how the rest of the season will play out, but it is my opinion it may be difficult to recover the costs associated with applying a fungicide this season, unless July and August turn wet.
Many double-crop fields are still not planted due to exceptionally dry soil conditions. However, double-crop soybeans do not generally respond well to foliar fungicides even in a season with decent moisture.
This may be a good year to consider leaving the fungicide sprayer in the barn.