About the Weed Management Handbook

Common lambsquarters (Chenopodium album)

Common lambsquarters (Chenopodium album) that has escaped both cultivation and herbicides in a snap bean field in western Oregon. Lambsquarters (also known as “fat hen”) was once regarded in Europe as one of the most delicious wild vegetables. It fell out of favor when spinach was introduced from southwest Asia in the 16th century. Now, lambsquarters is considered one of the most important weeds throughout temperate regions of the world. It germinates early in the season in the PNW and can grow to 5 feet before snap beans are harvested. If not controlled, it will significantly reduce yield, impede mechanical harvest and contaminate product, ultimately reducing the value of the crop. Lambsquarters is able to tolerate bentazon herbicide much better than it did 20 years ago. Bentazon is a critical tool for managing this weed in snap beans.

This handbook is designed as a quick and ready reference for weed control practices and herbicides used in various cropping systems or sites in Idaho, Oregon, and Washington.

This handbook will be useful to Extension agents, company field representatives, commercial spray applicators and consultants, herbicide dealers, teachers, and producers.

Recommendations are based on research results from the Agricultural Experiment Stations and Extension Services of Oregon, Idaho, and Washington. A few suggestions are included from research conducted in other states, and from U.S. Department of Agriculture research centers. In all cases, authors make every effort to list only registered herbicides, and to ensure that the information conforms to product labels and company recommendations.

Revision and Availability This handbook is updated annually. Individual sections are revised once each year; revision dates are listed at the start of each section.

Some sections may include additional online content, such as photos and links to related websites, publications, and other resources.

Please send comments or suggestions to handbook editor Ed Peachey (ed.peachey@oregonstate.edu).

Important Points to Remember

  • This handbook is not intended as a complete guide to weed control or herbicide use. Authors have assembled the most reliable information available to them at the time of publication. Due to constantly changing laws and regulations, authors can assume no liability for the recommendations.
  • Any use of a pesticide contrary to instructions on the printed label is illegal and is not recommended. Before using any herbicide, read the label on the container. Before a herbicide can be recommended for a specific use, it must be thoroughly tested. The recommendation on the manufacturer’s label, when followed, can prevent many problems arising from the improper use of a chemical.
  • Trade-name products and services are mentioned as illustrations only. This does not mean that the participating Extension Services endorse these products and services or that they intend to discriminate against products and services not mentioned. Commonly recognized trade names (brand names) of some commercial pesticides are used in this handbook to help identify the common name used by the Weed Science Society of America (WSSA), not as recommendations for that particular product.
  • Generic products: Many active ingredients are no longer under patent protection of the original registrant and are available under multiple trade names from different manufacturers. Pricing can vary meaningfully between trade names, as can active ingredient concentration, surfactant loading, and other formulation characteristics. Trusted retailers and consultants should be able to assist in identifying and comparing competing formulations of the same active ingredient. Several free, online search tools also facilitate searching and comparing formulations by active ingredient, and trade names including those from Agrian, CDMS, Farmers Business Network, and Greenbook. A limited number of trade names are presented per active ingredient for general reference. If generic products are available for an active ingredient, ‘several products’ or ‘several others’ is used to indicate the availability of other commercial formulations.
  • A note on premix products: Many herbicide formulations are available and include various combinations of two or more active ingredients in a premix. In general, only stand-alone formulations are considered in this handbook, unless an active ingredient is only commercially available in a premix product.