Mouseear Chickweed

Mouseear chickweed forms a dense, prostrate patch in lawns and gardens. It is a perennial weed that has small leaves 3/4 to 1 ½ inches long, about ½ inch wide, and shaped like a narrow triangle. The leaves are dark green and covered with short hairs that have a sticky-hairy feel to them, and small, white flowers that look like they have 8 petals, but are actually only 4, each with a deep lobe. Common chickweed is also found in Montana, but does not usually grow in grass; it is more commonly found in planting beds and under trees and shrubs. Common chickweed is more delicate in appearance, with lighter heart-shaped leaves that are not covered with hairs. Your county Extension agent can help you identify weeds that are causing problems for you. 

Mouseear chickweed roots are fairly shallow and can often be removed by hoeing, or in the garden, by hand pulling. New plants can grow from broken pieces of rootstock, however, so try and remove the entire plant when using this management method. Lawn grasses can often outcompete mouseear chickweed if the grass is not mowed too short and too frequently. Mow as high as possible and still keep the appearance acceptable, at least 2.5 inches high, cutting off not more than 1/3 of the grass length at a time. Watering your lawn deeply, so water soaks 6-8 inches deep, and not watering it again until the top inch of soil dries out, will encourage it to grow deeper roots, which can also help your turf outcompete shallow-rooted weeds such as mouseear chickweed. 

If an herbicide is used, chose a product which will move into the root system, killing the entire plant, such as glyphosate (e.g. Roundup). Glyphosate is of relatively low toxicity for humans and breaks down quickly in the environment, making it a good choice. However, it will kill both weeds and desirable plants, including trees, so apply it very carefully, allowing it to come in contact only with the plants you wish to destroy. 

Many herbicides labeled for chickweed contain the herbicide 2,4-D, but for mouseear chickweed, this is not effective. Herbicides that list dicamba as an ingredient, such as the trimecs, are usually more effective. Be sure to follow label instructions carefully when using any product that contains dicamba because it moves easily through the soil and can be very damaging to trees and shrubs when those roots are encountered. 

Whether you choose to manually remove chickweed or apply an herbicide, do it before the weed has time to go to seed, thereby reducing future problems. When using any pesticide, be sure to read and follow label instructions. 

References: 

Shurtleff, M., W. Thomas, and R. Randell. 1987. Controlling Turfgrass Pests. Prentice- 

Hall, Inc. Englewood Cliffs, NJ 07362. 449 pp. 

Thomson, W.T. 1994. Tree, Turf, and Ornamental Pesticide Guide, 1994-1995 Edition. 

Thomson Pubs., Fresno, CA 93791. 121 pp. 

Watschke, T., P. Dernoeden, and D. Shetlar. 1995. Managing Turfgrass Pests. Lewis Publishers, Boca Raton, FL 33431. 361 pp. 

Weed Control Guide. 1997. Meister Pub. Co. Willoughby, OH 44094-5992. 538 pp. 

Whitson, T., et al. 1991. Weeds of the West. Pioneer Printing, Jackson Wyoming. 630 pp. 

Written by Sherry Lajeunesse, Extension Urban Pest Management Specialist. Sept., 1997