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

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

3. Proper Identification Corn Earworm/Tobacco Budworm

7. 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

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

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

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

11. 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

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

13. 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.

14. Delays in Maturity

15. 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.