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Frost Damage in Corn


Early Season - When early frost kills corn leaf tissue, producers worry about whether or not corn plants will recover. The key to assessing corn seedling viability is to find and observe the "growing point." The growing point is where all new tissue originates and is protected below ground until the plants reach the V-5 stage. Removal or death of leaf tissue above the growing point has only a small effect on corn growth and yield at these early stages.

The growing point can be found by pulling the entire corn plant, including roots and splitting the entire plant lengthwise. If the growing point was below ground and white or creamy in appearance, then injury didn't occur. Observations of frost damage are best made by waiting at least two or three days after frost occurred. If the growing point appears healthy and is white to light yellow color several days after frost, full plant recovery is likely. Plants with extensive leaf tissue damage will likely recover if the growing point is not injured by early frost. New leaves should appear within three to four days if growing point is uninjured.

Late Season - If a killing frost occurs before grain fill is complete, yield potential and quality could be affected. A killing frost can occur when the temperature in the crop canopy drops from 32ºF to 28ºF for a short time (5-10 minutes) or if the canopy temperature stays at 32ºF for four to five hours. This is adequate to kill the entire plant. A lighter frost of 30-32ºF lasting an hour or two could kill leaves but not the stalk or ear shank. When only a portion of the leaves are killed, those not killed can continue to function and contribute to grain yield if good growing conditions follow frost. The effects of late season frost on killing leaves at various growth stages are shown below:

 Corn Grain Yield Reduction by Frost

Development Stage Days after Pollination Percent of Total Yield PERCENT Yield LOSS
Early Dent 35 68 32
Dent 40 77 23
Late Dent 45 85 15
Half Milk Line 50 92 8
Mature 55 100 0

Source: University of Minnesota