Weed management research conducted by the USDA-ARS group at Prosser is focused on reducing the impact of weeds in irrigated crops through various tactics including growing competitive crop cultivars, cultivation (tillage level), herbicides, and use of cover crops. Crops include alfalfa seed and forage, potato, sweet corn, spearmint, peppermint, carrots, onions, asparagus, hops, snap and dry beans, and switchgrass.

Besides reducing crop yield and quality, weeds are hosts of pathogens, nematodes, and insects that may attack crops. Weed hosts of tobacco rattle virus and stubby root nematode, the causal agent and vector of corky ringspot disease of potato have been identified as well as powdery scab of potato. The influence of weed presence on the durability of nematode resistance in potato lines has also been determined. Currently, weed hosts of potato cyst nematode are being identified to help the eradication efforts of this nematode in Idaho.

Sweet corn cultivars differ in canopy architecture and the ability to suppress weeds. The response of weeds to sweet corn hybrids and sweet corn’s ability to tolerate weeds are being evaluated in cooperative field studies at the Prosser ARS location and in Urbana, IL

Each year new weed species are reported that are resistant to currently used herbicides. Surveys of herbicide resistant weeds in Washington potato and mint fields are underway to document and develop strategies to manage this resistant biotypes.

In addition to our other weed management research, we also conduct 50 herbicide trials on container grown ornamentals (herbaceous perennials, shrubs, and trees) each year and submit the data to the national IR-4 program to support the registration of new tools for weed management for producers of these specialty crops.  Several local horticultural plant producers and nurseries donate nearly all the plant materials required to conduct these studies. Results of these trials and others conducted throughout the U.S. can be found on the IR-4 website.