Welcome to the PNW weed identification module

Listed below are profiles of many commonly found weeds in nurseries and field production sites throughout the Pacific Northwest, including Oregon, Washington, Idaho, and Northern California. Use this data base to assist with the Canada thistle floweridentification of problem weeds you may encounter in your own fields, nursery or landscapes. More weeds profiles will be added as often as possible.

Each weed profile provides basic biological traits and cultural preferences for that weed, but for control and management options, we direct users to the Pacific Northwest Weed Management Handbook.

The easiest way to use this handbook is to look under the “Contents” tab on the drop-down menu across the top of the home page. Under this tab, the user can select from various crop type categories such as Christmas trees, Nursery, Greenhouse and Bulb crops, or Turfgrasses. Select the appropriate crop category, click and find valuable information for developing a working strategy for weed management.

Recommendations in this handbook are based on research results from the Agricultural Experiment Stations and Extension Services of Oregon, Idaho, and Washington. It is designed as a quick reference guide for weed control practices and herbicides used in various cropping systems and sites in our Pacific Northwest area.

The Pacific Northwest Weed Management Handbook is an invaluable resource, providing information and useful tools to assist growers and other industry professionals. Check out the tabs on Pesticide Safety, Tables and Calculations, as well as a Safety Checklist.

Annual bluegrass Poa annua In the Pacific Northwest, annual bluegrass usually germinates in late summer through spring when moisture is adequate. Image by: James Altland, USDA-ARS
Annual Sowthistle Sonchus oleraceae Annual sowthistle is a very common weed in northwest field nurseries. Because it can germinate quite rapidly, it can quickly become problematic in agricultural areas. Image by:James Altland, USDA-ARS
Bittercress Cardamine oligosperma Bittercress is most problematic in propagation and overwintering of crops. It is most prolific from late fall through early spring. Image by: James Altland, USDA-ARS
Bittersweet Nightshade Solanum dulcamara Bittersweet nightshade is a perennial vine that easily forms into a rambling shrub if not controlled. It is a native of Europe and is also known as woody nightshade or simply bitter nightshade. Image by: James Altland, USDA-ARS
Bristly Hawksbeard Crepis setosa Bristly hawksbeard is common weed in landscapes, lawns and unmanaged areas. It is easily confused, particularly in the rosette stage, with other members of the Asteraceae family. Image by:James Altland, USDA-ARS
Broadleaf Dock Rumex obtusifolius Broadleaf dock, a perennial in the buckwheat family, has large, thick tap root. Image by: James Altland, USDA-ARS
Bull thistle Cirsium vulgare Bull thistle is one of the most common thistles the Northwest. In fact, the specific name vulgare means 'common'. Image by: James Altland, USDA-ARS
Canada thistle Cirsium arvense Canada thistle is extremely difficult to kill. A single plant can develop a lateral root system with a 20 foot spread in a single season. James Altland, USDA-ARS
Common chickweed Stellaria media Common chickweed is primarily a winter annual broadleaf in the Pacific Northwest, but in some coastal areas, it can survive year-round. James Altland, USDA-ARS
Common groundsel Senecio vulgaris Although groundsel is a winter annual, it is very adaptable and often germinates and grows year round in Oregon's generally milder climate. Image by: James Altland, USDA-ARS