Intra-ear compensation of field corn, zea mays l., from simulated injury by ear-feeding larvae

Ear-feeding larvae, such as corn earworm, Helicoverpa zea Boddie (Lepidoptera: Noctuidae), can be important insect pests of field corn, Zea mays L., by feeding on kernels.  Recently introduced, stacked Bt traits provide improved protection from ear-feeding larvae.  Our objective was to evaluate how injury to kernels in the ear tip might affect yield when this injury was inflicted at the blister and milk stages.  In 2010, simulated corn earworm injury reduced total kernel weight (i.e., yield) at both the blister and milk stage.  In 2011, injury to ear tips did not affect total kernel weight unless it was inflicted at the milk stage.  No differences in total kernel weight were found in 2013, regardless of when or how much injury was inflicted.  Our data suggested that kernels within the ear could compensate for injury to ear tips by increasing in size, but this increase was not always statistically significant or sufficient to overcome high levels of kernel injury.  The results indicate that intra-ear compensation for kernel injury to ear tips can occur under at least some conditions, and thus, the higher level of protection provided by new Bt corn traits against ear-feeding larvae may not necessary translate into increased yield.