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This publication examines how hail damages the corn plant, how the degree of damage can be determined and how the extent of yield loss is estimated.
In the U.S., approximately half of all hailstorms occur between March and May. These early storms are responsible for only minor corn yield losses, however, because the corn either has not yet been planted or is too small to be damaged significantly. Even when fields are severely damaged early in the growing season, they can often be replanted.
On the other hand, about a third of all hailstorms occur between June and September. These have resulted in yield losses to corn estimated at $52 million annually.
Hail affects yields primarily by reducing stands and defoliating the plant. Defoliation causes most of the losses. Thus, knowing how to recognize hail damage and assess probable loss is a very valuable decision-making aid.