Illinois Fertilizer & Chemical Association
Supply · Service · Stewardship

Frost/freeze damage report: will plants recover?

Temperatures over most of Illinois dropped to the upper 20s or low 30s on Saturday morning, May 9. This resulted in damage or even death to emerged and emerging corn and soybeans. The extent of damage was closely tied to when fields were planted.
Corn planted during the warm part of April—the first week—was up and growing (slowly) by May 1, with limited leaf area. In some fields, emerged stands were already subpar, especially in the wettest parts of the state, whether or not water stood in the field. According to NASS, 68 percent of the corn crop was planted by May 10, and 23 percent had emerged. With 8 percent planted by April 19 and 37 percent planted by April 26, we can estimate that corn planted by about April 23 had emerged by May 10. About 110 to 120 GDD accumulated between those dates in central Illinois. To match a similar GDD accumulation, that date would have been later in southern Illinois and earlier in northern Illinois.
Low temperatures on May 9 caused damage to emerged corn plants, and possibly to plants that had not yet emerged. With different low temperatures across regions, and with damage ranging from minor leaf loss to death, the only way to know if seedlings that are still alive will survive is to see if they produce new, green tissue after a few days with warmer temperatures. By early next week, we’ll know.
What we won’t know is whether or not damaged plants that produce minimal green leaf area, and that grow or regrow very slowly (these two are connected) will turn into thriving, productive plants. My suggestion is to take a “realistically pessimistic” approach to this, and to include in stand counts only those plants that look ready to make normal growth by May 17 or 18. With what we hope will be warm, drier weather coming after that, replanted fields should get off to a fast start, which will help to restore yield potential.
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