Noxious weeds are sometimes referred to as obnoxious weeds, and rightly so. They are non-native aggressive plants that threaten native habitats, economic sustainability, and often human health.

This is a good time of year to start looking out for noxious weeds in your property, and determining how best to manage them. Gilpin CSU Extension offers many resources for weed management, including technical assistance and identification, herbicide checkout program, and educational workshops. Please contact us for help at 303-582-9106 or Jennifer.cook@colostate.edu. Or learn more about noxious weeds on our website - https://gilpin.extension. colostate.edu/

Consider attending a free Noxious Weed Educational Workshop on June 21, 2022 at 6 pm at the Gilpin Public Library. Learn more about noxious weeds and identification. Then we will walk around outside to test our skills at identification and management.

Let’s get started now, with Scentless chamomile, a very tenacious noxious weed, common in Gilpin County and surrounding areas.

Scentless chamomile (Matricaria perforate) is reducing forage on summer mountain ranges for sheep, cattle and elk. It spreads very aggressively, crowding out native plants. Patches have been known to quadruple in a single year! The plant is a prolific seed producer; a single, healthy, robust plant can produce more than 300,000 seeds.

The flowers are white in color, ¾ inches, and are daisy-like flowers that are solitary on each stem. Flowers have a yellow central disk surrounded by white petals. Leaves are alternate, fernlike, finely divided, and odorless when crushed. The stems can reach 6 inches to 3 feet tall and have numerous branches.

The key to scentless chamomile management is to prevent it from going to seed. In Gilpin County, it will usually start producing seeds in mid-July. Because of a shallow root system, scentless chamomile can be pulled and bagged easily, preferable before it flowers and seeds. The other control option is to spray it before it flowers. Milestone used at label- recommended rates works well. Like most noxious weeds, control efforts will have to be maintained for a number of years, because of the long- lived seed bank.

Learn about other noxious weeds at our workshop on June 21, and/or checkout our website - https://gilpin. extension.colostate.edu/