The recent storms in South Dakota brought along rain, severe wind, and in some cases hail. With the hail and wind that occurred, many growers are wondering if a fungicide application is needed to protect their hail or wind-damaged crops (Figure 1) .
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. No yield response was seen, in these studies, in hail-damaged crops treated with fungicide. There is no research data available on fungicide use on hail-damaged wheat.
Diseases to Watch For
Bacterial diseases, which mainly infect plants through wounds or natural plant openings, may be elevated due to plants damaged by hail, sand blasting, or wind. Bacterial diseases observed after hail, sand blasting, or wind may include bacterial pustule and bacterial blight on soybean, bacterial leaf streak and Goss’s wilt on corn, and bacterial leaf streak and bacterial leaf blight on wheat. Fungicides do not offer protection against these bacterial diseases.
When Fungicides Are Warranted
Fungal pathogens do not require a wound (such as from hail, sand blasting, or wind) for infection to occur. Applying fungicides on hail damaged plants should only be warranted if there are significant fungal diseases developing on these plants. For example, in corn, significant fungal diseases would be Southern Rust, Tar Spot, and Gray Leaf Spot. In 2025, extremely low levels of these three diseases have been observed in the far southeastern counties. Southern rust is the only fungal disease that poses a significant threat to corn crops at this point and fields should be scouted for disease presence before application. Fungicides protect the yield potential of plants if significant diseases are present but do not improve the yield potential of crops. Both corn and soybeans should grow out of slight hail injury, unless the growing point was damaged. Recommended fungicide timings for soybeans are between R1 (white mold) and R3 for other fungal diseases and corn between VT and R1. Scout fields to determine if there is significant disease pressure developing and determine if the weather is favorable for disease development.
