Mechanisms and control of waterhemp populations resistant to group 15 herbicides
type: CreativeWork
description: Herbicides that inhibit very long-chain fatty acids (VLCFAs) have been applied for preemergence (PRE) control of annual grasses and small-seed broadleaf weeds for over sixty years. Waterhemp is a small-seeded, summer annual weed species native to the Midwestern United States. The species can be challenging to control due to important biological characteristics, such as reproductive output, genetic variability, seed dormancy, and an ability to evolve resistance to herbicides from multiple site-of-action groups. These and other characteristics allow waterhemp to effectively interfere with row crops and reduce seed yield potential. Waterhemp is resistant to herbicides from seven site-of-action groups, with resistance to VLCFA-inhibiting herbicides the most recently evolved. Control of two Illinois waterhemp populations (CHR and MCR) with the VLCFA inhibitor S-metolachlor was much less than expected in field research. An alternative VLCFA-inhibiting herbicide, acetochlor, remained relatively effective. Additional research was conducted to investigate VLCFA-inhibitor efficacy on each population in the field and greenhouse. Experiments identified few effective VLCFA-inhibiting herbicides for controlling CHR, and that both populations (CHR and MCR) displayed reduced sensitivity to acetochlor, dimethenamid-P, pyroxasulfone, and S-metolachlor under greenhouse conditions. The research presented herein was initiated in 2018 to identify the resistance mechanism(s) within CHR and MCR/SIR to the VLCFA-inhibitor, S-metolachlor. Chapter 1 includes a literature review describing waterhemp biology, waterhemp resistance mechanisms, resistance to soil-applied herbicides, VLCFA-inhibiting herbicides, and herbicide detoxification in plants. Chapter 2 described my initial laboratory experiments that identified rapid S-metolachlor metabolism was the resistance mechanism within CHR and SIR. CHR and SIR metabolized S-metolachlor twice as fast as sensitive waterhemp, but equally rapid as corn…
abstract: Herbicides that inhibit very long-chain fatty acids (VLCFAs) have been applied for preemergence (PRE) control of annual grasses and small-seed broadleaf weeds for over sixty years. Waterhemp is a small-seeded, summer annual weed species native to the Midwestern United States. The species can be challenging to control due to important biological characteristics, such as reproductive output, genetic variability, seed dormancy, and an ability to evolve resistance to herbicides from multiple site-of-action groups. These and other characteristics allow waterhemp to effectively interfere with row crops and reduce seed yield potential. Waterhemp is resistant to herbicides from seven site-of-action groups, with resistance to VLCFA-inhibiting herbicides the most recently evolved. Control of two Illinois waterhemp populations (CHR and MCR) with the VLCFA inhibitor S-metolachlor was much less than expected in field research. An alternative VLCFA-inhibiting herbicide, acetochlor, remained relatively effective. Additional research was conducted to investigate VLCFA-inhibitor efficacy on each population in the field and greenhouse. Experiments identified few effective VLCFA-inhibiting herbicides for controlling CHR, and that both populations (CHR and MCR) displayed reduced sensitivity to acetochlor, dimethenamid-P, pyroxasulfone, and S-metolachlor under greenhouse conditions. The research presented herein was initiated in 2018 to identify the resistance mechanism(s) within CHR and MCR/SIR to the VLCFA-inhibitor, S-metolachlor. Chapter 1 includes a literature review describing waterhemp biology, waterhemp resistance mechanisms, resistance to soil-applied herbicides, VLCFA-inhibiting herbicides, and herbicide detoxification in plants. Chapter 2 described my initial laboratory experiments that identified rapid S-metolachlor metabolism was the resistance mechanism within CHR and SIR. CHR and SIR metabolized S-metolachlor twice as fast as sensitive waterhemp, but equally rapid as corn…
author: Strom, Seth Arthur
language: en
keywords: Herbicide resistance, metabolism, waterhemp
date published: 2021-09-17T01:10:43Z
date modified: 2026-07-22T22:24:50Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois at Urbana-Champaign

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2142/110450