By Connie Strunk
Figure 1. A soybean field West of White damaged by hail on July, 11, 2017.
The recent storms in East South Dakota brought along rain, high wind, and in some cases hail. Some corn and soybean fields have heavy hail damage (Figure 1). With the hail that parts of Brookings and Codington counties received, some growers are wondering if a fungicide application is needed to protect their hail damaged crops.
Do post-hail fungicide applications increase yields?
In Illinois, research conducted on corn using simulated hail damage did not show significant yield increases from fungicide applications of Headline, Quadris, or Quilt. Similarly, research conducted in Wisconsin under natural hail events showed that Headline on corn (at R2 stage of growth) and Headline, Quilt, and Stratego on soybeans (at R3 stage of growth) also did not result in increased yield. These studies indicate no yield response as a result of fungicide application on hail damaged crops.
What diseases should you watch for?
Bacterial diseases, which mainly infect plants through wounds, may be elevated due to hail damage. These include bacterial pustule and bacterial blight on soybean and Goss’s wilt on corn. Fungicides do not offer protection against these bacterial diseases.
When are fungicides warranted?
Applying fungicides on hail damaged plants should only be warranted if there are significant fungal diseases developing on these plants.
"Fungicides protect the yield potential of plants if significant diseases are present but do not improve the yield potential of crops," Strunk said.
She explained that both corn and soybeans should grow out of slight hail injury, unless the growing point was damaged.
Scout and apply a fungicide when soybean is between R1 and R3 and corn between VT and R1 and when significant disease pressure is developing and weather is favorable for disease development.