Because of its aggressive growth and persistent nature, Bermuda grass is very difficult to kill and eradicate completely from a lawn where it has grown vigorously. It is one of those grasses which can return even after it appears dead.
Bermuda grass is a serious weed in cool-season turf grass because it turns an ugly brown color from October through April, and it rapidly creeps into flower beds, neighbor’s lawns and onto sidewalks. Bermuda grass, a warm-season grass, commonly invades during the summer when cool-season grasses such as Kentucky bluegrass and fescue are under heat and drought stress. It is a problem only in full sun, i.e. it does not grow well in shade. Bermuda grass spreads by underground lateral stems (rhizomes), above ground lateral stems (stolons) and to a lesser extent, by seed.
While trying to remove Bermuda grass, just digging it up will not solve the problem. Several applications of herbicide are required over a month to kill 90 to 95% of Bermuda grass.
Herbicide like glyphosate (commonly known as roundup) is very common for killing Bermuda. But remember, in order to get good results, herbicide should be applied (i.e. sprayed) on the grass leaves. This is because the leaves are the most effective part to absorb maximum quantity of herbicide.
Another important point to remember is the time of herbicide application. In dormant state (like in January) Bermuda grass absorbs less herbicides. This is the time when they draw nutrients up from the roots and therefore the chemical applied on the leaves is unlikely to reach down to the root system. So this is not the time to kill Bermuda by use of herbicides. Application of herbicides should be done during the summer months, when the leaves are fully developed and green.
Although completely eradicating Bermuda grass is very difficult, it is possible to get it under control. Reseeding with tall fescue and following a good maintenance program that favors tall fescue and not Bermuda grass is the key.