Agdex No. 273.21

INTRODUCTION

A green, weed-free, healthy looking lawn is an important part of a home landscape. A well kept lawn, uniform in texture and colour, is only possible when broadleaf weeds and weedy grasses are not present. Weeds compete with desirable grasses for moisture, nutrients and sunlight as well as hosting plant diseases and insects. It is therefore important to control weeds in lawns.

CULTURAL CONTROL OF WEEDS

1. The most effective way to avoid lawn weeds is the use of proper lawn care practices. Good seed bed preparation, and the use of quality lawn seed will develop a thick healthy lawn. Practices such as liming, fertilizing, mowing, watering, aerating and reseeding sparse areas produces a lawn that is a strong competitor with weeds and therefore reduces weed infestation.
2. Pulling weeds by hand is effective in reducing weed numbers over a small area. If removed before producing seed, further weed reproduction is prevented.
3. Cutting or mowing is effective in controlling broadleaf weeds over larger areas. It prevents weed-seed formation and makes desired grasses more aggressive.
4. Digging cuts off the weed plant just below the ground. One digging will kill annual weeds. Perennial weeds (plants which live for more than two years) can be killed if top growth is removed repeatedly after new shoots appear, through the growing season.

Herbicides are used to control weed species that are otherwise difficult to control. The two major kinds of weeds found in lawns are: broadleaf weeds (e.g. dandelions, plantain) and grassy weeds (e.g. annual bluegrass, crabgrass). Several chemical herbicides are recommended to control these weeds.

2,4-D is a selective herbicide that kills many broad-leaf weeds. It is not an effective control for black medick, chickweed, clover, ground ivy, and heal-all. Care is required around flower and garden plants, as spray drift can damage them. 2,4-D is often used in commercial herbicide mixtures with mecoprop, dichlorprop, and dicamba and sold under various trade names. These mixtures control a wider spectrum of weeds than any of the chemicals do alone. Do not use 2,4-D or dicamba or newly seeded lawns.

 Most herbicides are available in several forms. Concentrated liquids are mixed with water and applied with a sprayer or watering can. A granular herbicide/fertilizer mixture makes two steps in lawn care, one simple operation. Other formulations include aerosol bombs and wax canes that are good for spot application of herbicide.

 Herbicides are most effectively applied - when the weeds are young and actively growing (May to early June, Sept., or both if the weed population warrants it). Visible results from the use of these herbicides can usually be seen in about two weeks.

 Bensulide, and siduron are preemergence herbicides used to control annual grasses such as crabgrass. Siduron is applied in the spring while bensulide can be applied in spring or fall.

Do not mow the lawn the day before applying herbicide and wait 2-3 days after applying herbicide before mowing to ensure adequate coverage.

Use all agricultural chemicals in accordance with the instructions and limitations found on the label. Consult the N.B. Dept. of Agriculture for further information.