D3140: Field evaluation of Surtivo for management of corn earworm and soybean looper in soybean

Corn earworm (CEW), Helicoverpa zea and soybean looper (SBL), Chrysodeixis includens cause significant yield losses in soybeans (Glycine max). Because CEW and SBL typically reach economic threshold at different times in soybean, growers often need to apply multiple chemical insecticidal sprays. Nuclear Polyhedrosis Virus (NPV) insecticides can be used to control these pests to preserve yield. In our study, we evaluated the effectiveness of a new NPV insecticide (Surtivo) in comparison to a standard chemical insecticide. Surtivo belongs to IRAC mode of action group 31 (host-specific occluded pathogenic viruses) and represents the first pre-mixture of HearNPV and ChinNPV for expended spectrum to control both CEW and SBL. We hypothesized that when Surtivo is applied at CEW timing, SBL neonate larvae present in the treated field at subthreshold levels will become infected and allow for the ChinNPV in Surtivo to replicate and spread. Therefore, suppressing the local SBL population below economic threshold and protecting the soybean plants from yield reducing foliar damage. Surtivo was applied at 2.6 oz per acre when at least 4 small (1^st and 2^nd instar) CEW and and 1 small (1^st and 2^nd instar) SBL were present per 100 sweeps. The comparative chemical insecticide was applied when 9 CEW larvae were present per 25 sweeps and when 17 SBL larvae were present per 25 sweeps. Assessments of larval counts, pod damage, and leaf defoliation were conducted weekly for 6 weeks after the 1^st spray in each treatment. Results will be discussed.