Weeding Killing Crabgrass

No other field of agricultural research has received more interest and attention since the end of World War II than chemical weed control. Starting with the development of 2,4-D in 1945 for the control of broad-leaved weeds, the tremendous interest and enthusiasm of this new era has expanded to include the control of crabgrass, public enemy number one of lawns.

Advice and counter-advice has been mounting ever since. There are three important steps in the successful control of crabgrass in lawns. First and, by far, the most important is good lawn maintenance. Second is a knowledge of the pest and its growth habits. Third is the proper use of chemicals where emergency measures are required.

There is no substitute for a properly constructed, carefully maintained lawn. While the chemical industries are continually developing newer and better weed killers, the best of these materials serve but a single purpose, that of eradicating the pest for the current season. Unless suitable grasses, adequate fertilization, proper clipping and satisfactory watering practices are maintained both before and after treatment the crabgrass will come back at least in part.

“Money in the Bank” Information

Practically all state experiment stations and many commercial firms publish bulletins on lawn care and maintenance in their particular areas. The first step is to obtain one of these publications and follow it. This information is “money in the bank” because by following the prescribed practices, the permanent grasses are given the advantage over crabgrass which does not tolerate shade and finds a dense, healthy turf its natural enemy.

However, during periods of high temperatures and intensive drought the permanent lawn grasses often go into temporary dormancy when growth is reduced or stops entirely. It is at this time that crabgrass invades the weakened turf. Once the pest has made its appearance on a large scale chemical control is necessary to arrest its development.

The broad, pale green annual, crabgrass, first appears in late May or June in areas of thin or weakened turf. Great numbers of seeds are in the soil and continue to germinate throughout the summer. Since crabgrass thrives best when days are long and temperatures high, midsummer finds the young crabgrass competing vigorously with the lawn grasses.

Neglected Lawns

In neglected lawns, crabgrass often becomes the only grass present. By mid-August and early September seeds begin to form on characteristic fingerlike seed shoots. Tremendous numbers of seeds are produced by a single plant and even though they become buried in the soil for many years they germinate when brought to the surface and exposed to suitable conditions. Unfortunately, often it is not until the seed-head stage that the plants are recognized as crabgrass. Then it is too late for most effective control because additional seeds have already been scattered over the soil. Also, by this time the plants have developed long spreading runners which hug theground and crowd out the permanent grasses.

As the cooler days of fall approach the growth of crabgrass declines until frost. Then the plants turn a deep purple and die. On the other hand, with the approach of cooler days the permanent lawn grasses recover and, if not crowded out, resume growth.

Because of the close-growing, spreading habit of crabgrass mowing is not an effective control. In fact, the close mowing during midsummer is more harmful to the permanent grasses than the pest. The basic grasses of our northern lawns, bluegrasses and fescues, should not be clipped below 1% inches during the summer season. While effective on small areas, hand weeding is laborious and inefficient when attempted on a large scale.

Chemical Control and Formulation

Several chemicals have been brought before the public as crabgrass killers. Formulations of these materials are available every growing season in practically every garden or supply store in the crabgrass belt.

With so many preparations available the matter of selecting the right one can be perplexing. In general, different liquid forms of the same material give about the same results at comparable cost. Check with your local garden center or nursery for the best treatment for crabgrass in your area.

Related Articles

• Crabgrass Control the Dry way - The use of dry chemical formulations has long been one of the most effective ways to control crabgrass in turf. The popularity of this method has been due to the ease with which dry materials may be applied and the effectiveness of only one or two applications. The reason that chemical sprays have been unpopular with
• The Serious Lawn Amateur Speaks Up - Lawn grass is made up of an assortment of perennial grasses most of which are extremely winter hardy and cold loving. An established lawn of almost any regular high-grade grasses comes out of the coldest winter early and unscathed. Troubles usually begin in the middle of the summer in the crab-grass belt (an area with long