A fast-growing warm-season grass, Bermuda grass (Cynodon dactylon) thrives in U.S. Department of Agriculture plant hardiness zones 7 through 10 -- so much so that it's considered invasive in some areas. Bermuda grass spreads so quickly it can take over your existing lawn. This isn't a problem if you enjoy the look and feel of Bermuda grass, but when you want to get rid of it without killing other turf, use an herbicide such as atrazine.
How It Spreads
Bermuda grass spreads in two ways: rhizomes and seeds. It can grow underground rhizomes from just a small sprig, quickly taking over an area of your lawn. When allowed to grow long enough, it develops seeds to aid in the spread. It grows best in full sun, and it doesn't need as much water as some other types of grass. It can creep under your edging to invade your flowerbeds as well as your lawn.
How Atrazine Works
Atrazine often is used to kill clover, broadleaf weeds and crabgrass, but it weakens Bermuda grass as well. It doesn't kill Bermuda grass, however. Atrazine stuns the grass by inhibiting photosynthesis, preventing its growth temporarily -- for a couple of weeks, usually -- giving your existing grass time to take back areas claimed by the Bermuda grass. Spraying the area with a ready-to-use liquid version of Atrazine is the most effective way to weaken the Bermuda grass.
Adding Other Herbicides
Using a mixture of herbicides -- one of which is atrazine -- works better to kill the Bermuda grass than atrazine alone. Ethofumesate, for example, helps control broadleaf and grassy weeds in cool-season grasses. When Bermuda is invading these areas, using both herbicides at the same time helps eliminate it. Atrazine weakens the grass, and ethofumesate delivers the final killing blow by upsetting the cellular division process.
Help atrazine work against your Bermuda grass problem by adding new cultural practices. Mowing your grass taller than normal -- as tall as your mower will allow -- helps create shade on the Bermuda grass, which can kill it. Fertilize your lawn adequately to keep it from being stressed; Bermuda grass thrives when other grasses start to fail. Water your grass deeply and spread out the waterings rather than giving just a little water every day to the grass. This encourages your existing grass to choke out the Bermuda grass, rather than the other way around.