Dallisgrass has been growing everywhere in many home lawns and other turfgrass areas in Oklahoma. Professional lawn weed control companies have had some success, but it is still difficult to control. So, what is a control that homeowners may use?
The plant is frequently growing in pastures, lawns, golf courses and other turf areas especially in humid states. Dallisgrass reproduces by very short rhizomes and seeds in the summer. It produces an abundance of seeds on long spikes that grow several feet tall. Each spike carries 2-10 spikelets and each spikelet has two rows of seeds running along its length. The seeds are spread by wind, animals, and adhering under the lawn mower. A tough weed to kill invading our lawns and gardens especially in unmowed areas.
The dallisgrass weed hails from Uruguay and Argentina. It was introduced into the United States back in the 1800s as a fast-growing forage plant that could survive our southern climates. Its common name is a tribute to A.T. Dallis, who was an ardent supporter of its use and imported it around the turn of the century. Too bad he made a mistake and his name is now attached to such a malicious weed.
As it turns out, the dallisgrass weed likes it new environment so much that it soon grows out of control. Dallisgrass has become established over most of the south.
Dallisgrass control has become a concern for both homeowners and public turf areas. It is a course textured perennial that grows in an ever-enlarging circular clump, sometimes growing so large that the center dies out while the outer rings continue smothering all the turf grasses they encounter. Its short rhizomes take roots easily in moist soil, making it difficult to control.
Dallisgrass weed thrives in sandy or clay soils. It loves nitrogen fertilizer and grows twice as fast as regular turf grasses, which can create obstructions for golf courses, fields, athlete fields and unsightly tufts for the homeowner. Seed heads seem to grow overnight.
Control of dallisgrass is threefold: lawn health, pre-emergent and post-emergent weed controls.
The first method of dallisgrass control is to maintain a healthy, dense turf with proper watering, mowing and fertilization. Bare spots should be filled quickly with seed or sod to prevent dallisgrass weed seeds from taking hold. Mowing often with a bag will catch weed seeds preventing them from following to the soil. A thick, well maintained lawn, where unwanted seed has no room to germinate, is a sure dallisgrass control method.
The second stage to control dallisgrass involves pre-emergent weed control. A pre-emergent herbicide that will control crabgrass will also be on effective dallisgrass control. Pre-emergent must be watered into the soil to be completely successful.
There are three useful post-emergent treatments for dallisgrass control. Digging out the offending plants is the most environmentally friendly method to control dallisgrass, but it’s also the most labor intensive. Post emergent herbicides that are used for crabgrass control will also work well, although they must be applied several times at 2- to 3-week intervals to complete the treatment and prevent regrowth.
Finally, spot treatments with non-selective herbicides such as Roundup, can be useful for minor infestations. A cautionary word about this method of dallisgrass control, non-selective herbicides may kill any plant they come in contact with. Turf will be killed along with weeds. Be prepared to fill in those bare spots with seed or sod as quickly as possible. Follow label directions for re-seeding.
Dallisgrass is a plague on our turf lawns throughout Oklahoma, but with attentiveness and a little knowledge about how to kill it and how to prevent its return, this malicious weed can be eradicated from your lawn.
Jim Coe lives in Lawton.