Nutsedge, or "nutgrass", Cyperus esculentus, is a lawn weed with erect triangular yellow-green stems and narrow, grass-like leaves originating at the base of the plant. Its seedhead is yellow-brown in color. Nutsedge is an adaptable weed that makes its home in low ground along water courses or in rich sandy soils where gardening is practiced. It is a triplet species because it can reproduce from a perennial base, nut-like tubers beneath the soil surface and by seeds. The nut-like tubers are what make nutsedge difficult to eradicate. If the plant is not completely removed from the soil and the tubers remain, they can produce new plants in your lawn.

Management:

New Lawns
The greatest source of weed seeds in new lawns is the soil itself. Planting at the proper season with the right grasses and adequate fertilization at seeding time are the most important practices in minimizing weed problems. In the Northeast, late summer (August 20 - October 1) planting is almost the only means of preventing nutsedge from taking over the lawn. When planted in late summer, the grass plants will spread laterally and the turf will be dense and mature before most troublesome lawn weeds appear.

Established lawns
Most common lawn weeds can be greatly reduced by improved lawn care, including proper fertilization and mowing. Sometimes, however, weeds persist in spite of good maintenance.

For small lawns or where there are only a few weeds, hand pulling as weeds appear can give good temporary results. Weeds can be pulled more easily after a heavy rain or watering. The use of herbicides to control weeds is more practical for large areas, more difficult-to-pull weeds and small patches of persistent weeds. Large areas can be treated with sprays or granules, which give good weed control with minimal injury to turfgrass. Single clumps of weeds can be spot treated. Aerosol "spot weeders" are available for such areas. When weeds infest an area of any size and the populations are high enough throughout the area to be objectionable an overall treatment with a selective chemical that will kill the weeds and leave the grass unharmed may be necessary. Where weed infestation is serious and the turf is poor, consider renovating the lawn.

Check the herbicide label for the proper way and most effective time to apply herbicides.

To minimize weed problems:

• Select the recommended grass for your site
• Plant your new lawn in the late summer
• Use adequate fertilizer (and limestone if needed), especially when starting a new lawn
• Mow your lawn to a height of at least 1-1/2 inches to better compete with weeds
• Control diseases and insects that damage turf and allow weed encroachment
• Water the lawn deepl andthoroughly, not too little too often

Herbicides:

If necessary, apply bentazon (Basagran) in late June to early July; repeat in 10 to 14 days if necessary. The high rate has injured ryegrass turf; avoid such applications during hot weather to minimize the chances of injury; or apply halosulfuron (Manage) at the 3- to 8- leaf stage with an nonionic surfactant. A second application may be needed 6 weeks later; or apply methanearsonate (MSMA) when first active spring growth occurs. Repeat the application in 10 to 14 days. It may discolor the turf.

Adapted from Tom Kowalsick, Cornell Cooperative Extension, 2001