Scentless chamomile (Matricaria perforata)

Photo credits: Irene Shonle and La Plata Weed Office

Quick Facts:

Scentless chamomile was brought over from Eurasia as an ornamental, but now has escaped cultivation and became a troublesome weed in the West.
It can be found from 5000 ft. up to 12000 ft. elev.
Scentless chamomile is a member of the Sunflower family, and is an annual, biennial, or short-lived perennial plant.
It has white ray and yellow disk flowers which look like typical daisies, and it blooms from June through August. It can be distinguished from Oxeye daisy by the fine, ferny leaves. It can be distinguished from pineapple weed, a native weed, by pineapple weed’s pleasant pineapple scent (crush the foliage) and that pineapple weed does not have any white “petals”

Scentless chamomile is spreading and reducing forage on summer mountain ranges for sheep, cattle and elk.
It can cause skin rashes and blistering of livestock and wild animal’s muzzles. 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, which stay alive in the soil for a long time.

The key to control for scentless chamomile is to prevent it from going to seed. In Gilpin County, it will start going to seed mid-July.
Scentless chamomile has a shallow root system, which allows it to be pulled or dug relatively easily.
There is no biological control for this plant.
Herbicides such as Roundup are fairly effective when applied at label rates.
Cultural controls, such as increasing desirable grass levels, may also help outcompete the weed.
Because of the long-lived seed bank, control efforts will have to be maintained for a number of years.