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Archive for Sunday, April 8, 2001

Take action to win turf battle with crabgrass

April 8, 2001

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For the most part, home lawns in our area are either cool-season grasses, warm-season grasses or a combination of both.

Cool-season grasses grow better in the summer north of here and warm-season grasses survive winters better south of here.

We live in what is called the transition zone or what I call the "crabgrass belt." In other words, crabgrass is what we grow best.

So if you are like me and find crabgrass to be your No. 1 weed problem, here are some pointers to help make your lawn green and crabgrass-free.

Begin your crabgrass control program by reviewing basic lawn care practices. Crabgrass is not the cause of an unhealthy turf, it is the result.

As the desirable grass dies out, crabgrass moves in. The best way to stop crabgrass is to prevent it.

To make your lawn less desirable for crabgrass, raise the mowing height. A taller lawn reduces the amount of sunlight that reaches the soil, and cuts the number of sprouting weed seeds.

Next, water as needed. Too much or too little water weakens the roots of grass and causes the stand to be sickly and sparse.

Finally, fertilize in May, September and November. Applying too much fertilizer or applying it at the wrong time may only give the crabgrass more energy for growth and development.

Once you understand those basics, it's time to use pre-emergent herbicides. These crabgrass-preventers are chemicals that stop young plants from emerging.

Because proper application prevents crabgrass from popping out of the ground, and because some advertisers falsely claim so, many folks believe that these herbicides keep the seed from germinating. Not true.

Rather, the germinating plant encounters the herbicide in the soil as it tries to emerge from the ground and is killed. This scenario is actually more beneficial than if these herbicides prevented germination, because the killed seed is no longer viable and cannot cause future problems.

Barricade and Dimension are two commonly available crabgrass preventers. Barricade can be applied in the fall for crabgrass control the following season. When used on a fertilizer carrier, it should be applied in the fall.

Dimension is unique because it can be applied after the crabgrass has germinated, as long as the plants are still small. (And procrastinators will be happy to learn that Dimension can be applied through early May with good results.)

Both products have longer residual activity than other crabgrass preventers. This means two things: You can apply these herbicides early in the spring, and you don't have to make a second application as with some other products.

For newly seeded lawns or lawns seeded last fall, use a product called Tupersan. It is somewhat less effective than other pre-emergence herbicides but does not harm the newly seeded grass. Tupersan provides short-term control so an additional application will be necessary about six weeks after the first.

Crabgrass is not a native grass. It was introduced in 1849 as animal feed. Unfortunately, settlers were able to grow it well and now it flourishes in all 48 continental states.

To keep your lawn crabgrass-free, evaluate your lawn care program, use pre-emergent herbicides and remember this old saying: April showers bring May flowers and a lot of crabgrass too.

Bruce Chladny is horticulture agent at K-State Research and Extension-Douglas County. For more gardening information call the Master Gardener Hotline, 843-7058, from 9 a.m. to noon

and 1 p.m. to 4 p.m. Monday, Wednesday or Friday.

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