About the Weed Management Handbook

A photo of orange hawkweed seeds and flowers.

Orange hawkweed (Hieracium aurantiacum), with its beautiful flowers, has been grown as an ornamental species since 1875. Even Gregor Mendel was interested in hawkweeds, using orange hawkweed in verification experiments on laws of inheritance. They have been called Mendel’s nemesis since apomixis was not understood then, making verification of inheritance laws challenging. Hawkweeds continue to be grown as ornamentals, risking introduction of new invasive hawkweeds. While native hawkweeds do not have stolons, those introduced did, allowing us to tell them apart. Unfortunately, some recently introduced hawkweeds don’t have stolons. Hawkweeds can reduce forage production by 70 percent in pastures.

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 semiannually. Individual sections are revised once each year; revision dates are listed at the start of each section. Most sections are also available as PDF documents on the weed handbook website: http://pnwhandbooks.org/weed

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. Trade names (brand names) of some commercial pesticides are used in portions of this handbook to help identify the common name used by the Weed Science Society of America (WSSA).