Herbicide Management for Bromus tectorum to Enhance Rangeland Productivity in Western Nebraska

Authors

Miranda Mueller, University of Nebraska-LincolnFollow

First Advisor

Mitchell B. Stephenson

Second Advisor

Nicholas A. McMillan

Committee Members

Nevin Lawrence, Bijesh Maharjan

Date of this Version

4-2025

Document Type

Thesis

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: Agronomy

Under the supervision of Professors Mitchell B. Stephenson and Nicholas A. McMillan

Lincoln, Nebraska, April 2025

Comments

Copyright 2025, Miranda Mueller. Used by permission

Abstract

Cheatgrass, Bromus tectorum (L.), has increased in the mixed-grass prairies of the Nebraska Panhandle. Limited research is available in these ecosystems on the ecological factors that influences its spread and options for management. This study focuses on the efficacy of herbicide treatments (indaziflam and imazapic) as a cheatgrass control method on the native rangelands of western Nebraska. In September of 2022, a mixture of indaziflam (73 g ai ha^-1, Rejuvra) and imazapic (70 g ai ha^-1, Plateau) was aerially applied at 6 unique upland ecological sites (1-3 ha) near Scottsbluff, NE. Functional group plant biomass data were collected in treated and closely associated untreated rangelands in late June through early July of 2023 and 2024. Cheatgrass biomass in treated areas was 98% less (p < 0.01) than in untreated control areas in both year one and two following herbicide treatment. Perennial grass biomass in herbicide treated areas was 3.2 times greater (p < 0.01) than untreated areas and trends showed increasing forage nutritive values as the percent of cheatgrass in the plot decreased. We also used greenhouse gas analyzers (LI-COR LI-7820 N₂O/H₂O trace gas analyzer for N₂O emissions and a LI-COR LI-7810 CH₄/CO₂/H₂O trace gas analyzer for CO₂ and CH₄ emissions) to explore differences in GHG emissions within different treated and untreated plant communities. While more years of data will give us a better understanding of the long-term influence of indaziflam and imazapic to remove cheatgrass on western Nebraska rangelands, the first two years of this study show promise for success of these treatments in western Nebraska ecosystems.

Advisors: Mitchell B. Stephenson, Nicholas A. McMillan