Dominic Reisig NCSU Entomology and Plant Pathology 2017 Soybean Insect Update Dominic Reisig NCSU Entomology and Plant Pathology

Making Smart Insecticide Choices in Soybean Proper identification Numbers at threshold Choose the correct tool

Proper Identification Corn Earworm/Tobacco Budworm

Corn Earworm Risky Safe Pyrethroid Caterpillar-specific Advantages (Baythroid, bifenthrin, Karate, Mustang, Tombstone) Advantages Cheap (unless they flare), pick up some true bugs Disadvantages Resistance, not effective on many armyworms, loopers, tobacco budworms, kill many natural enemies Caterpillar-specific (Blackhawk, Intrepid Edge, Prevathon, Steward) Advantages Almost always effective, some residual, preserve beneficials Disadvantages Initially pricey, will not pick up true bugs

Average mean % corn earworm moth survival, 5 µg cypermethrin- 2013-2016

Number of predators per beat sheet sample Untreated Belt Prevathon Karate + Prevathon (Besiege) Number of predators per beat sheet sample Work done during 2013-2015 in NC and VA by VA Tech student Dr. Rebecca Whalen

I don’t understand why I have worms…I already sprayed

Do multiple defoliation events compound to reduce yield in soybeans? V3 Defoliation V6 Defoliation   33% 66% 100% 97% 96% 77% 105% 93% 88% 83% 95% 101% 92% 86% 75% 79% Yield (% of UTC) Basically what I get out of this is that you really arent getting much yield loss on vegetative soybeans until you get over this 66% defoliation, and most these beans got defoliated twice and still werent seeing any substantial yield loss until 100% defoliation was reached. B.C. Thrash, A. Catchot, J. Gore, F. Musser, D. Cook, T. Irby, J. Krutz- MS State

V4 Defoliation Soybeans in each planting date were either left alone or defoliated 100% at the V4 growth stage.

Effects of Soybean Planting Date on V4 Defoliation Damage Stoneville However in stoneville, we saw a general decrease in yield as planting dates got later and no pattern in the amount of yield loss as the season progressed. The differences between locations was likely attributed to differences in weather and soil types.

Delays in Maturity

Conclusions Do reproductive thresholds need to be adjusted based on defoliation that occurred during vegetative growth stages? Probably not Later planted soybeans may need a lower treatment threshold to compensate for reduced leaf area recovery time Probably not. Defoliation that occurred earlier in the season had minimal effects on yield loss caused by defoliation later in the season.