Hilling as a Management Tactic and Tool for Understanding Soybean Gall Midge (Resseliella maxima Gagné)

Authors

Pragya Gupta, University of Nebraska-LincolnFollow

First Advisor

Anthony Justin McMechan

Date of this Version

4-2024

Citation

A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science

Major: Entomology

Under the supervision of Professor Anthony Justin McMechan

Lincoln, Nebraska, April 2024

Comments

Copyright 2024, Pragya Gupta. Used by permission

Abstract

Soybean gall midge (Resseliella maxima Gagné, SGM) emerged as a new species in the United States Midwest in 2019, causing injury to soybean (Glycine max L.) Infestation of R. maxima starts with females laying eggs in the fissures or cracks that develop at the base of soybean during the V2-V3 growth stage. The emerged larvae feed on the stem internally, leading to wilting and death of the plants. With knowledge gaps in biology and behavior, management strategies for this pest are challenging. Hilling is a cultural practice causing soil to cover the base of stems and is effective in mitigating SGM infestation.

A two-year field study was conducted to better understand the timing of hilling as a management practice. Hilling was performed at different timings (V2, V5, and R2) of soybean growth stages. Treatments were arranged as randomized complete block and Latin square designs in 2022 and 2023, respectively. The effectiveness of hilling timing was evaluated by the proportion of infested plants, larval abundance, plant injury, and yield. The results showed that hilling at the V2 and V5 growth stages had reduced infestation and protected yields compared to later hilling at the R2 stage.

The second study focused on understanding the temporal impact of unhilling on soybean gall midge abundance, plant injury, and yield components. Hilled plots were unhilled every 15-20 days, starting with the V2 stage and collecting plants. Plots were arranged as randomized complete blocks near Mead, Nebraska, in 2022 and 2023. At the end of the season, plants were collected to evaluate yield components for the number of nodes, pods, seeds, and seed weight. Reductions in yield components at the V2 were found for all except for node count in 2023. Unhilling at R1 impacted seed weight in both years.

Both studies are the first to explore the timing of hilling as a management for R. maxima and the temporal impact of fissure exposure on soybean yield components. The results from these studies can provide insights into the potential window for effective management of R. maxima and its temporal impact of infestation on yield components.

Advisor: Anthony Justin McMechan