Amit J. Jhala
Date of this Version
Barnes E.R. (2019) Challenges and opportunities for weed control in Nebraska popcorn. Ph.D. Dissertation. Lincoln, NE: University of Nebraska-Lincoln
Weed control in popcorn is challenging with limited herbicide options and popcorn’s perceived sensitivity to herbicides. Understanding the impact of weeds maximizes yield and profit. New herbicide-resistant crops increase chances of drift or misapplication into popcorn, which doesn’t have herbicide-resistant traits. Herbicides that are labeled in popcorn are often only conditionally labeled with reduce rates, warnings, or limited popcorn types. Dent-sterility in popcorn is contingent on the Ga1 gene (Ga1-s), but this system is at risk from Ga1-m field corn introduced from Mexico because it overcomes dent-sterility. This risk is under-assessed as Ga1-m carriers are undocumented and Mexican germplasm usage is increasing for genetic diversity. Experiments conducted 2017-2019 are assessing weed control, herbicide sensitivity, and popcorn purity risk.
Chapter 1 outlines the history of popcorn in the United States, current production practices, agronomic challenges, herbicide use in popcorn, and a strategic plan for improving popcorn production. Chapter 2 determines the critical time for weed removal in popcorn produced with and without atrazine/S-metolachlor applied pre-emergence (PRE). Chapter 3 determines weed control options and crop injury potential of five herbicide programs on eight popcorn hybrids. Chapter 4 evaluates the efficacy and crop safety of labeled post-emergence (POST) herbicides for controlling velvetleaf that survived S-metolachlor/atrazine applied PRE in Nebraska popcorn and determines the effect of velvetleaf growth stage on POST herbicide efficacy, popcorn injury, and yield. Chapter 5 examines the effects from drift or misapplication of herbicides to white and yellow popcorn. Chapter 6 models the cross-pollination of popcorn by field corn and investigates the factors influencing contamination and isolation distance.
Advisor: Amit J. Jhala