Larimer County Weed District

Curlycup gumweed, also referred to as rosinweed, is a biennial or short-lived perennial in the sunflower family (Asteraceae) that is native to North America. Curlycup gumweed is found in disturbed areas, fields, meadows, and roadsides. This weed is easily identified by the sticky flower heads and bright yellow flowers. Plants grow to 3 1/2 feet high with much branching.

A biennial, such as curlycup gumweed, is a plant that completes its life cycle in two seasons or two years. This weed reproduces from seed only. Therefore, the control of this biennial should include the prevention of seed production.

Selective chemical control (only broadleaf plants are affected) of this plant can be achieved with products that contain 2,4-D such as 2,4-D Amine 4, Brash, Barrage, Curtail, Saber, and Turret. Non-selective control (all plants are affected) can be achieved with herbicides containing glyphosate such as RoundUp, Rattler, Razor, and Credit. Areas with a susceptibility of water contamination such as lake shores should be treated with herbicides with such as Rodeo or Eagre. See label for specific rates and timing of application. However, these herbicides, in general, are applied when the plant is actively growing; preferably when the plants are in the early bud stage. It is also recommended to use a surfactant when applying these herbicides. For additional questions, please call Suellen at the Weed District, 970-498-5768.