A Review of Corn Earworm Threshold in Grain Sorghum

The corn earworm, Helicoverpa zea (Boddie), is the most economically damaging lepidopteran insect pest of grain sorghum in Mississippi. Recently, concerns were raised about the validity of the current economic threshold of one larva per panicle for this pest. To address this concern, experiments were conducted in Stoneville, MS utilizing artificial infestations with second instar corn earworm larvae. Larvae were infested at eight densities ranging from 0 to 6 larvae per panicle. Additionally, infestations were done at two plant densities. Plant density did not have an impact on feeding injury or yield losses caused from corn earworm, so data from both densities were combined. Data analyses suggest that the current threshold will not change based on finalized results.