May 17, 2023
Yellow Alyssum is Becoming a Problem in lawns
As a result of drought conditions, large patches of yellow alyssum are turning up in lawns across Chouteau county. Yellow alyssum (Alyssum alyssoides) is native to northern Africa, eastern Europe, and western Asia. The weed was brought to North America for medicinal purposes because it was said it could cure hiccups, mental illness, and rabies.
Yellow alyssum is an annual forb belonging to the Mustard family (Brassicaceae). Plants are relatively short with yellow flowers, growing from 3-10 inches tall. Each plant is usually multi-stemmed and branches from the base.
Yellow alyssum grows at low to mid-elevations in disturbed soils of grasslands, steppe, streambanks, or roadsides, as well as rocky areas. Yellow alyssum can invade undisturbed areas and grow with established perennial bunchgrasses. Yellow alyssum relies on seed production for reproduction. Since it is an annual forb, populations can fluctuate widely from year-to-year. Yellow alyssum can be weedy on disturbed sites, particularly on areas where lawn is sparse. The species is relatively unpalatable to livestock. However, the seeds and foliage are eaten by western harvester ants, rabbits, pronghorn antelope, and sage grouse.
Since yellow alyssum thrives in disturbed soils, it is
important to take steps towards making your desired lawn more competitive with weeds. Additionally, alyssum control should happen before seed production to limit persistence and spread. Plants may be mown just before flowering, or small patches of alyssum may be hand-pulled and disposed of in the trash. Herbicides recommended in lawns are 2,4-D or glyphosate. Herbicide applications in the fall may be most effective because yellow alyssum often grow as a winter annual, meaning it emerges in the fall, overwinters as a seedling, and resumes growth, produces seed, and dies in the spring. In the fall, alyssum will be in a vulnerable seedling stage. Always seed grass after spraying. Keep the soil moist to help the grass get established. A competitive lawn is the best practice for yellow alyssum management.
Information for this article came from the Montana Weekly Weed Post compiled by Jane Mangold ( MSU Extension Invasive Weeds Specialist)
Montana State University, U.S. Department of Agriculture and Montana Counties Cooperating. MSU Extension is an equal opportunity/affirmative action provider of educational outreach.