COLUMN: GARDENING: Bermuda grass can't be controlled

If you have gardening questions, call the Master Gardeners' hot line at 257-5555 between 9 a.m. and 4 p.m., Monday through Friday. There is also a gardening Web site at http://www.intermind.net/ mgarden/.

For those of you who are interested in relandscaping your yard from all grass to partial or complete desert landscaping, please give our Master Gardeners a call at 257-5555 and leave your name, address and telephone number. The next seven-week class is starting in early January and space is limited.

We have a new faculty member who joined us recently who will coordinate our home horticulture program. Her name is Dr. Angela O'Callaghan who recently came to us from Cornell University. She will be coordinating our Master Gardener program, as well as community gardens and school horticulture programs. If you have any questions about these programs, please give her a call at 222-3130.

Even though this probably isn't the best time of the year to be talking about controlling Bermuda grass in home yards I thought this might be a good time to tell you what you can do this coming year. Unfortunately, Bermuda grass will probably never be totally controlled in our climate as long as water is being applied to landscapes but there are some things you can do to thwart its aggression and keep it as a minimal problem.

I guess the keyword here is management rather than control. Bermuda grass is a warm season grass. This means that it does very well during hot times of the

year and changes at colder times of the year by becoming dormant. Dormancy is a rest phase of its life cycle when it simply becomes inactive until warm temperatures and water become available to it again. At this time of the year Bermuda grass is inactive because of cold temperatures and so may turn brown. In some locations in town there are warmer and wet microclimates where you will still see green Bermuda grass. Otherwise, the above ground parts of this plant will die and turn brown. If you were to take your thumbnail and scrape away the outer brown layer of these brown plants at their protected base, you may be able to still see a green stem underneath. This indicates the base of the plant may still be alive, but inactive.

Bermuda grass roots and rhizomes can go very deep in the soil. Their depth may be several feet to tens of feet deep, depending on where water and oxygen are located in the soil. In the coldest parts of the valley, the rhizomes are the parts of the Bermuda grass plant that will rejuvenate the above ground part once warmth and wetness return. In warmer locations, the above ground part may simply start growing again. In any case, if this Bermuda grass were a lawn, we would mow it very close to the ground in April when air temperatures were in the high 70s or 80s to help rejuvenate it for summer growth. Mowing it short helps to warm the soil earlier and, along with fertilizer and water, stimulate new growth.

Bermuda grass has several ways it can reproduce itself and spread. One is by seed. Those Bermuda grasses which produce viable seed can spread by means of mowers, on the bottom of shoes, water runoff and animals. Keeping Bermuda grass closely cut or trimmed will keep this problem to a minimum. Never or seldom cutting weedy areas will of course encourage the seed to spread to nearby areas or areas visited by vectors of the seed.

Bermuda grass can also spread through cuttings. Horticulturists and agronomists call these cuttings sprigs or stolons. Sprigs and stolons are underground and above ground stems that have been cut into short pieces. Each of these pieces can start a new plant or, for that matter with time, a new lawn or patch of Bermuda grass weeds. A method that some companies use for starting a new lawn of Bermuda grass is to use sprigs and stolons as propagating material. They take sod and pulverize it, sometimes with a device called a hammermill, remove the soil and put the chopped grass in bags. These bags of sprigs or stolons can then be used to start a new lawn. Spreading these plant parts on top of the soil, raking them into the topsoil or covering them with a top dressing and fertilizer and watering, starts it. That's all it takes.

This is the reason it doesn't work to rent a sod cutter or rototiller to get rid of an existing area of Bermuda grass. This might work to some degree on

tall fescue, but in this case, Bermuda grass simply propagates and renews itself when rototilled. The most effective method of control is to kill the

underground stems, called rhizomes, which renew the plant each spring. This is very difficult to do unless you use some sort of poison that will move through

the plant to the rhizomes once it enters the plant. This is why the weed killer Roundup can be somewhat effective.

Roundup is a systemic herbicide; one that travels through the plant once it enters it, which was originally developed to kill grasses. To be effective on

Bermuda grass, it must enter the plant once sprayed on the actively growing above ground parts and travel to the rhizomes. First, the plant must be actively green and growing when sprayed.

Secondly, it would be best to spray in the fall when the transport of sugars is toward the rhizomes, preparing itself for next spring's growth. It is suggested that the Bermuda grass should be mowed or line trimmed first before applying this weed killer. Roundup is a general weed killer, it is nonselective. It does not distinguish good plants from bad plants. You must make this decision for it. What you spray, in this case, is what you will most likely kill.

This makes it very difficult to control Bermuda grass when it is growing in close proximity with other plants. If the Roundup overspray falls on plants that are important to you, then of course they will probably die too. There are a couple of chemicals that have been developed that are selective and will kill, for the most part, only grasses and not harm things like flowers and ground covers. These two chemicals are called Fusilade and Poast. These chemicals may be listed as ingredients in other products that you may find in nurseries and garden centers. They have been approved for use in killing Bermuda grass growing in flowers, ground covers and shrubs and will not harm most of them. You must check the label for application instructions and precautions. It seems that Fusilade has been more effective than Poast in field trials in other parts of the country.

As with any weed control program, any effective management plan must include diligence. This means that just because you spray once in the fall and the

Bermuda grass seems to turn brown and die, it does not mean your troubles are

over. Any time you have water and bare soil, you will have a Bermuda grass weed problem. The most effective way to minimize these problems is to use mulches whenever you have bare wet soil. Bermuda grass can't survive in total shade, and applying a mulch will give the soil total shade. This will aid in prevention.

Once Bermuda grass appears, it must be dealt with immediately. Hoe or remove young plants. Spray it with nonselective weed killer like Roundup in a spray bottle if you need to. Or you can use Poast or Fusilade as the label directs.

Bob Morris is a horticulture specialist with the University of Nevada Cooperative Extension.