Reducing runaway weeds

Herbicide applications made in the fall will keep weeds and dandelions from spreading in the spring.

When thinking about lawns in the fall, most gardeners remember that you should fertilize, aerate and perhaps seed. But the last thing they seem to think about is weed control. Yet if you will control broadleaf weeds in the fall, you will find that few dandelions will raise their ugly yellow heads in the spring.

In the spring most gardeners are bothered with dandelions, chickweed and henbet. Blooming dandelions seem to signal the time for most lawn owners to get after lawn weeds. Unfortunately by the time they get the job done, the dandelions have gone to seed. Herbicide applications will get rid of the dandelions that are present, but unfortunately those thrown seeds will germinate and a new crop of biannual dandelions will rear their ugly heads during the late spring and early summer.

The story is a little different for chickweed and henbet. Both of these weeds are winter annuals. Their seed germinates in the early fall after a few good rains. After germination the weeds don't grow much. They just sit there until the following spring when temperatures begin to warm up. They then grow rapidly, bloom and throw seed. Finally when summer comes, these weeds die.

If you are bothered in the spring by yellow blooming dandelions, purple blooming henbet or white blooming chickweed, I suggest you take a different approach to control. Don't wait until early next spring to make an herbicide application. If you will take the time to make an herbicide application right now, you will find that most of the weeds that plague your lawn in the spring will be gone.

Fortunately, one herbicide, trimec, will control most of the broadleaf weeds that are found in your lawn. This herbicide comes in many different forms, such as a liquid concentrate, a ready-to-use liquid, and a granule, packaged both as an herbicide only, and as an herbicide mixed with fertilizer.

Growing weeds to death

Trimec works by entering the plant through foliage. It will not enter a plant through the root system. Once the systemic herbicide enters the plant it travels throughout the plant and kills foliage, stems and roots.

Trimec is a synthetic plant growth hormone. It forces weeds to grow themselves to death. In order for the herbicide to work most effectively, weeds should be growing rapidly. Therefore don't use this herbicide when temperatures are really cool, below 40 degrees, or during a drought.

Since trimec must be introduced into the weed through its foliage, the best method of application is by spraying. If you have weeds in a small confined area, use a ready-to-use product. But if most of your lawn is covered with weeds, the most economic product to use is a concentrated liquid. Personally I like to use a hose end sprayer when making a liquid trimec application. You can use a pumping pressure sprayer, but you will find that it takes a much longer time to apply the herbicide this way.

Many gardeners prefer to make a granular application of trimec. But weed foliage must be wet for that application. When a trimec granule hits the foliage of a weed, the moisture on the leaf acts as a glue to keep the granule on the leaf. It takes about 24 hours for all of the herbicide to soak out of the granule and be introduced into the weed leaf. Therefore, it must not rain for 24 hours after application.

Using a granule on small-leaved weeds sometimes results in poor weed control. Again, the herbicide granule must stick to the leaf in order to get control. If you have such a weed, you have a small target for the granule to hit. I usually recommend that for small-leaved weeds, use a liquid application. You get better results.

If your lawn was plagued by yellow dandelions, purple henbet or white chickweed last spring, try making a fall application of trimec. You will find that one application in the fall will generally provide you with a weed-free lawn next spring.

Send your gardening and landscape questions to Paul Schnare at P.O. Box 699; Cape Girardeau, Mo. 63702-0699 or by e-mail to news@semissourian.com.