Garlic Mustard

Skamania County’s Least Wanted

Garlic Mustard (Allaria petiolata) was first found in Skamania County in 2007. At the time, this was the third county in Washington to report infestations of this Class A listed noxious weed.

What is the ecological threat?

Garlic Mustard poses a severe ecological threat to native plants and animals in forest communities. Many native wildflowers that complete their life cycles in this region occur within the same habitat of Garlic Mustard. Garlic Mustard out-competes native flora by aggressively monopolizing light, moisture, nectar, roots, soil and space. Wildlife species that depend on the native flora in the early season are deprived of essential food sources once Garlic Mustard has established. This plant is allelopathic, meaning that it exudes chemicals from its roots which prevent the growth of other plants, which in time can create large monostands of Garlic Mustard.

Biology and Spread

After spending the first year of its two-year cycle as a rosette, Garlic Mustard develops rapidly following spring into mature plants which flower, produce seed and die. A single plant can produce thousands of seeds, which are capable of scattering many meters away from the parent plant. In this region, a single plant may self-fertilize without the assistance of pollinators.

Plant Description

Garlic Mustard is a cool season biannual herb with stalked, triangular to heart shaped, coarsely toothed leaves. When these leaves are crushed, the leaves give off a distinct odor of garlic. First-year plants appear as a rosette of green leaves close to the ground. The rosette will remain green through the fall and winter and develop into mature plants during it’s second year. Flowering plants of Garlic Mustard grow from 2-3 feet in height and produce button-like clusters of small white flowers, each with four petals in the shape of a cross. Near the beginning of summer, seeds are produced in erect, slender pods and become shiny and black when mature.

Garlic Mustard poses a very serious threat to the health of our forest ecosystems in Skamania County. For further information please view the Garlic Mustard handout at the link below or view a special movie which explains the effects of Garlic Mustard in the eastern United States. If you have suspected infestations of Garlic Mustard, please contact us as soon as possible so that we may assist you. For more information please contact Justin Bush at bush@co.skamania.wa.us or by phone at 509-427-3941.