The weed Yellow Nutsedge (Cyperus esculentus) is a grass-like perennial identified by its triangular stem and yellowish-green color. It is particularly noticeable in lawns in July and August when it grows more quickly than desirable bluegrass or red fescue and sticks out above it.

Yellow Nutsedge thrives in poorly drained, rich soils and lawns that have been watered excessively. It reproduces from seed and from small "nutlets" which grow at the root tips, and may persist in the soil during the weed's dormant stage.

Yellow Nutsedge Illus: Weeds of the North Central States

If you have only a few plants, pull out the plants before each lawn mowing to control them. Heavier infestations are difficult to control. Two or three treatments in late June and July with a herbicide containing DSMA or other methanearsonates (MSMA or MAMA) will reduce stands of yellow nutsedge. These are the chemicals commonly found in post-emergence crabgrass killers, also called "crabicides." Sometimes the product will also contain the common broadleaf herbicide, 2,4-D. Repeat applications at 7 to 14 day intervals if necessary, and if weather is cooperative.

Apply methanearsonates ONLY when temperatures range in the 60s and 70s. Turfgrass injury may occur when air temperatures exceed 80 degrees. Also, never apply these chemicals when the lawn is under stress, especially drought stress.

The information found on the product label is important for the product's safe and effective use. Always read and follow the label directions carefully. Failure to do so may brown the lawn by chemically burning the grass blades.