Refining Helicoverpa zea (Boddie) sampling recommendations in Kansas sorghum

Sorghum, Sorghum bicolor (L.) Moench, ranks fifth in total acreage and production among the world’s cereal crops with Kansas leading US production. Sorghum headworm, Helicoverpa zea (Boddie), is an annual insect pest of grain sorghum with yield reductions ranging from 10% to 25% at 1-2 larvae per panicle. Statewide, Kansas growers must make headworm treatment decisions that impact total grain production, profits, and refugia for beneficial insects. However, inefficient sampling methods are time-consuming and costly. Consequently, current sampling strategies for sorghum headworm do not account for larval spatial distributions within an infested field. By identifying key sampling areas within a field and refining established sampling recommendations we can then develop site-specific management practices, which hold great promise for minimizing yield loss and reducing unwarranted insecticide applications. The primary objective of this research was to define reduced sampling areas (field borders vs. whole-field) that can accurately estimate larval infestations based on geospatial distributions. To date, field data show that neighboring host-crops like corn or soybean can influence the spatial colonization patterns of sorghum headworm at the field-level. In conjunction with sequential sampling plans currently under development, these results will provide sorghum growers and consultants with time-efficient, site-specific sampling strategies for managing production sorghum fields.