Ecology and Management of Hoary Alyssum (Berteroa incana (L.) DC.)

Invasive Species Technical Note Number MT-22

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Invasive Species Technical Note Number MT-22 (PDF; 468 KB)

By Jim Jacobs, Plant Materials Specialist, NRCS, Bozeman, Montana
Jane Mangold, Assistant Professor of Integrated Invasive Plant Management, Montana State University, Bozeman, Montana

Abstract

Hoary alyssum, a member of the mustard family, is an annual to short-lived perennial forb native to east-central Europe and western Asia. It has a slender tap root, star-shaped hairs on the stems, leaves, sepals, and seed pods, and four white, notched petals on flowers clustered at the stem tips. Dependent on seed production to maintain populations and to spread, flowering begins in late spring and lasts through fall enabling a single plant to produce over 2,500 seeds when growing on open ground. First reported from Ontario, Canada in 1893 and the northeast coast of the U.S. in 1897, it spread to Montana by 1905 and currently is reported from 27 Montana counties (a distribution map of hoary alyssum can be found at the University of Montana Invaders Database. It was designated a category 1 noxious weed in Montana in 2008. In the 1950s and 1960s, hoary alyssum began to proliferate in forage crops, pastures, and rangelands. It is opportunistic and fills voids left in disturbed areas and on over-grazed range and pastureland (see Figure 1). Toxicity to horses has been reported when green or dried forage is contaminated by more than 30%. Infestations reduce the species richness of pollinator communities because they attract a minimal number of pollinating insects.

Figure 1. Hoary alyssum growing next to alfalfa.

Hoary alyssum can be controlled using 2, 4-D applied at bloom. Re-applications will be required to prevent seed production. There are no biological control insects available and grazing management has not been developed. Prescribed grazing to maintain the vigor of forage species will prevent invasion and retard spread. In forage production fields, nutrient management, irrigation management, and crop rotation to maintain vigorous forage plants will prevent hoary alyssum invasion and reduce spread.

Plant Biology

• Identification
• Life History
• Habitat, Spread and Impacts

Management Alternatives

References

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Last Modified: 11/18/2008