Sweet corn is an important processing crop in the upper Midwestern United States. It can be insured for hail losses, but actuarial tables are based on field corn. The first step in developing accurate yield loss estimates is to determine yield loss due to stand loss. The second step is to determine yield loss due to defoliation. To understand the impacts of defoliation on sweet corn yield, we compared ear yield with estimated 25, 50, 75, or 100% of leaf area removed at five times throughout the growing season to control plots that were not defoliated. Defoliation was carried out with a Christmas tree shearing knife or machete. We repeated this in three consecutive years at two locations, without irrigation or supplemental fertilizer. Yield was measured as both green ear mass and cut kernel mass. Measured loss due to defoliation was generally less than actuarial estimates, except shortly before tasseling or at 25% defoliation. A regression equation predicting yield relative to control based on a) growing degree days before damage and b) percent defoliation were developed, combining all site-years. We measured little yield loss with 25 or 50% defoliation or 75% defoliation near V8, and we measured greatest yield loss near tasseling with 100% leaf removal. Kernel and ear mass were strongly correlated. These results illustrate resilience of sweet corn to foliage loss and potential need for adjustment of actuarial tables for hail loss.
