Location: Global Change and Photosynthesis Research
2024 Annual Report
Objectives
Objective 1: Develop control measures for weeds in vegetables, fruits, and specialty crops. [NP304, C2, PS 2A]
Objective 2: Determine herbicide residues in harvested product. [NP 304, C2, PS 2A]
Approach
Candidate herbicides for use in minor crops will be identified. Herbicides alone or in combination with other tactics will be evaluated under field conditions and crop and/or weed responses will be determined.
Progress Report
Significant progress has been made on Objective 1, developing control measures for weeds in vegetable crops.
Four manuscripts are being finalized by coauthors that describe the scope and complexity of weed issues in lima bean and snap bean in the United States, including the Northeast, Midwest, and Pacific Northwest regions. This research is in support of Sub-objective 2.1 (determine the scope of the problem of weeds and their management in processing vegetable legumes, specifically snap bean) of parent project 5012-12220-010-000D. The objectives of the four manuscripts are as follows:
1) Lima bean paper: a) quantify the residual weed communities in lima bean, and b) characterize weed management practices employed by growers
2) Snap bean paper #1: a) quantify the residual weed community in snap bean grown for processing across the major growing regions in the United States, and b) investigate linkages between the density of residual weeds and their contributions to weed canopy cover
3) Snap bean paper #2: characterize crop and weed management practices employed by the growers
4) Snap bean paper #3: identify the most important management practices and environmental factors on the weed community and snap bean yield
ARS researchers in Urbana, Illinois are also exploring solutions to manage weeds that currently escape control. Weeds in the pigweed family are problematic in snap bean production because stems of pigweed plants that escape control break into pod-sized fragments during crop harvest, contaminating consumer products. Several preemergence herbicides suppress pigweed species; however, snap bean tolerance to such herbicides is poorly documented. This research identified two herbicides, dimethenamid-P and lactofen, that appear safe for use in snap bean production. The impact of this research is that it supports an effort to develop a federal label for use of dimethenamid-P and lactofen on snap bean. Such an outcome would be a welcome addition to the weed management arsenal in the crop. This research is currently in press with Weed Technology.
ARS researchers in Urbana, Illinois continue to use a snap bean diversity panel to investigate important agronomic traits, specifically tolerance to various herbicides including flumioxazin. They found that snap bean's ability to survive an application of the herbicide flumioxazin is due to multiple physiological pathways that are controlled by a master element located in chromosome 2. The existence of a single element able to regulate the expression of a large number of genes involved in stress tolerance is of high interest for basic science and applied crop breeding. Conceivably, excessive reliance on flumioxazin or related herbicides for weed control could select for phenotypes of weed species that are enriched in tolerance mechanisms identified in this research. This manuscript is currently in press with Frontiers in Plant Science.
ARS researchers in Urbana, Illinois have also done research that helps the popcorn industry. The United States grows and consumes more popcorn than any other nation. Herbicides registered on popcorn often are available for use on yellow kernel hybrids but not white kernel hybrids. An evaluation of a diversity panel of 362 popcorn accessions identified two groups of popcorn within the panel. The first group, dominated by yellow kernel accessions, had limited genetic diversity and tolerance to nicosulfuron herbicide compared to the second group, dominated by white kernel accessions and sensitivity to nicosulfuron. Candidate genes conditioning response to nicosulfuron appear to differ from previous research findings in field corn and sweet corn. The research showed that popcorn population, not kernel color, accounts for differential response to nicosulfuron. This work is published in Crop Science.
In regard to Objective 2, herbicide residues in vegetable crops was not conducted because herbicide residues are not the limiting factor for product registrations on snap bean and popcorn, but rather, unknown crop tolerance to herbicides.
Accomplishments