Agronomy and Horticulture Department


First Advisor

Amit J. Jhala

Date of this Version

Fall 10-2019


Barnes E.R. (2019) Challenges and opportunities for weed control in Nebraska popcorn. Ph.D. Dissertation. Lincoln, NE: University of Nebraska-Lincoln


A DISSERTATION Presented to the Faculty of The Graduate Collage at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Agronomy and Horticulture (Weed Science), Under the Supervision of Professor Amit J. Jhala. Lincoln, Nebraska: October, 2019

Copyright 2019 Ethann R. Barnes


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