Will the increased planting of indeterminate soybean varieties extend the time Helicoverpa zea (Boddie) can infest soybeans?

Helicoverpa zea (Boddie) is an economically important polyphagous pest of many crops, including soybean Glycine max (L.) Merr. Historically, soybean varieties with a determinate growth habit predominated in the southeastern USA, but growers have been planting more varieties with an indeterminate growth habit in recent years due to associated yield benefits. Our hypothesis is that H. zea infestation time may be extended with indeterminate varieties, since flowering soybeans are preferred ovipositional sites and indeterminate varieties typically flower longer than determinate varieties. Furthermore, H. zea infestations are more likely in later planted soybeans, especially those that are double cropped (planted behind wheat). With more plantings of double cropped indeterminate varieties, H. zea infestations may also be extended and, subsequently, modifications to management recommendations may be merited. We designed field experiments to document H. zea ovipositional patterns between growth habits and to test if soybean plants with different growth habits would compensate differently for yield loss from H. zea . These results will better describe H. zea ecology in soybeans and support our understanding of soybean yield compensation to H. zea feeding; ultimately this information will help provide recommendations for managing H. zea in soybean production in the Southeast USA.