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ARS Home » Southeast Area » Stoneville, Mississippi » Southern Insect Management Research » Research » Publications at this Location » Publication #396478
Research Project: Insect Control and Resistance Management in Corn, Cotton, Sorghum, Soybean, and Sweet Potato, and Alternative Approaches to Tarnished Plant Bug Control in the Southern United States

Location: Southern Insect Management Research

Title: Effects of soybean plant population on yield loss from defoliation

Author
item THRASH, BENJAMIN - University Of Arkansas
item CATCHOT, ANGUS - Mississippi State University
item GORE, JEFF - Mississippi State University
item COOK, DONALD - Mississippi State University
item MUSSER, FRED - Mississippi State University
item IRBY, TRENTON - Mississippi State University
item KRUTZ, JASON - Mississippi State University

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/9/2020
Publication Date: 1/27/2021
Citation: Thrash, B.C., Catchot, A.L., Gore, J., Cook, D.R., Musser, F.R., Irby, T., Krutz, J. 2021. Effects of soybean plant population on yield loss from defoliation. Journal of Economic Entomology. 114(2):702-709. https://doi.org/10.1093/jee/toaa279.
DOI: https://doi.org/10.1093/jee/toaa279

Interpretive Summary: Soybean planting densities vary widely across fields in the Mid-South region of the United States due to a myriad of factors. It was unknown if yield loss from insect-related defoliation varies across differerent soybean stand densities. Soybean was planted in Starkville and Stoneville, MS, in 2016 and 2017 at five seeding rates. Each seeding rate contained a nondefoliated plot and a plot that was defoliated 67% at the early flowering growth stage. Defoliation reduced yield where plant densities were <192,800 plants/ha, but greater densities were not affected. Reduced yield in defoliated plots when compared with nondefoliated plots indicated that some resources were used to replace the removed leaf area instead of seed production. These results suggest that fields with substandard plant densities might benefit from a reduced treatment threshold for defoliating pests.

Technical Abstract: Plant densities in Mid-South U.S. soybean, Glycine max (L.) Merr., fields can vary greatly due to a wide range of factors, although soybean yields are generally insensitive to variations in density. Currently, it is unknown if yield loss from insect-related defoliation varies across different soybean stand densities. Soybean was planted in Starkville and Stoneville, MS, in 2016 and 2017 at five seeding rates ranging from 123,500 to 420,070 seed/ha in 74,130 seed/ha increments. Each seeding rate contained a nondefoliated plot and a plot that was defoliated 67% at the R1 growth stage. Defoliated plants had a greater leaf expansion rate from R1 to R3 than nondefoliated plants. Defoliation reduced yield where plant densities were <192,800 plants/ha, but greater densities were not affected. Reduced yield in defoliated plots when compared with nondefoliated plots at equivalent R3 leaf area index values indicated that some resources were used to replace the removed leaf area instead of seed production. These results suggest that fields with substandard plant densities might benefit from a reduced treatment threshold for defoliating pests.