Temperatures this morning (May 3) reached 25 degrees with many corn and soybean fields getting close to emerge. In a few fields, crops have just started to emerge and with the low temperatures many may wonder if replanting now is needed.
Corn can tolerate low temperature and substantial leaf injury can occur without loss in stand. The growing point is located below ground (approximately 0.5 inch below surface) and is not likely to be damaged by the frost. Emerged plants have their growing point above the soil surface and can suffer from frost more easily than corn. The soybean seedling has two vegetative buds in the cotyledonary axils. Regrowth can occur from either of these vegetative buds if they have not been frozen.
Wait at least 48 hours before you determine if replanting is needed. New growth should be visible the day after the frost, if the temperature is about 65 to 70 degrees. Also, hold back a few days so the plant has recovered before applying post emergence herbicides or fertilizers. For more information on soybean replant decisions see Soybean Replant Decisions  (PDF). Please remember that a few lost soybean plants may not have a significant impact on yield.
This article originally appeared on page 35 of the IC-492 (7) -- May 10, 2004 issue.