Winter weeds

Henbit is a type of winter weed that can be easily controlled by fall pre-emergent herbicide applications.

The fall season is an excellent time to prepare the lawn for the winter months and give it a jump start on next spring. The next few weeks are the prime time to do the following:

 Fertilize

Fertilizer may be applied to cool-season grasses during the fall. Of course it is best to fertilize according to soil-test results, but if a soil test has not been done, then fertilize according to nitrogen needs. Fescues generally require 1 to 5 lbs. of nitrogen per 1000 square feet per growing month. Therefore, apply nitrogen at this rate in October and November.

Remember, though, the more nitrogen added, the more often the lawn will need to be mowed. If too much nitrogen is used, the chances for disease increases.

There isn’t too much that needs to be done at this time to the warm-season grasses. These grasses shouldn’t be fertilized after August, but a pre-emergent herbicide may be applied until mid-October.

Apply herbicide

Fall is a very good time to look at weed control, especially using pre-emergence products.

Pre-emergence treatments are applied before weeds sprout from seeds. Apply two weeks ahead of germination. For North Alabama, the ideal time to apply them is in early October.

If you put these out too early, less effective control may be expected (i.e. more than a month before seed germination). Applications should not be made until excess lawn clippings and leaf litter are removed.

Homeowners will find many pre-emergence products at local garden centers for control of summer annual weeds. Many are often referred to as “crabgrass preventer.” They are available in both liquid and granular forms.

Be sure to follow label recommendations for application rates and watering requirements. Crabgrass preventers, for control of summer annual grasses, require water or rainfall to activate.

Fertilizer-herbicide combinations are extremely popular because they combine two operations. Combinations with pre-emergence chemicals are generally effective since both fertilizer and herbicide action are dependent on contact with the soil (requiring rainfall or irrigation).

Post-emergence herbicide action depends more on absorption by leaves, and granules in such combinations do not adhere well to smooth-surfaced leaves. They will stick better if applied when weed leaves are damp, perhaps with morning dew.

Keep in mind “weed and feed” materials sometimes present a conflict in desirable actions. Proper time for weed control often does not coincide with the most desirable time and rates for fertilizing. If used for follow-up fertilizations, there is danger of herbicide overdose.

If you wait until after the weeds appear, you will need to apply post-emergence products. A fall application of post-emergence products is often successful because many of the perennial broadleaf weeds are rapidly growing in the early fall.

By applying in the fall, there is generally less risk of injury to desired plants. Also, both perennial and winter annual seedlings can be controlled. Also, perennials weakened by herbicide may be killed by winter weather.

Although most herbicides are formulated with reliable safety factors, application rates higher than those recommended may cause injury to turf and ornamental plants. Many people over apply herbicides, especially when using fertilizer-herbicide combinations. The user needs to follow instructions on containers carefully to avoid overdoses.

Proper fertilizing, watering, and mowing practices will provide a healthy lawn year-round.

 — Becker is a regional agent for the Alabama Cooperative Extension System. For information on topics related to the home and garden, contact any ACES office. The Limestone County office is at 1109 W. Market St. in Athens. Office hours are 8 a.m. to 4:30 p.m. Mondays through Fridays. For more information, call 256-232-5510 or visit www.aces.edu.

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