Crabgrass and Annual Grassy Weeds

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Crabgrass is one of the most common annual grassy weeds. They grow, mature, set seed and die in less than 12 months or when killed by frost. Other annual grassy weeds are goosegrass, foxtail, barnyard grass, fall panicum and sandbur.

A good thick stand of grass is your best defense against annual grassy weeds. Preemergence herbicides can be used to control annual grassy weed plants. They work by killing the grass plant before it has a chance to emerge from the soil. In order for the material to work it must be applied before the seed germinates in the spring. In this area we suggest that preemergence herbicides be applied before April 15th.

There are also postemergence herbicides available. They are applied after the weed plant has started growing. Postemergence herbicides work best if the plants are small, in the 1 to 3 leaf stage. Make sure the grass you want to keep is not under stress when you use a postemergence herbicide. Check the label for any restrictions.

There are many preemergence and postemergence herbicides available for annual grassy weeds. Check with your county Extension office, master gardener office or garden center for a list of materials that are labeled for annual grasses. Follow the label directions for application rates.

Crabgrass

Tom Fowler, FowlerT@missouri.edu
Regional Specialist, Agriculture and Horticulture
Buchanan County, MO
University of Missouri Extension