When looking at large areas of lawn contaminated by weeds, most people consider resorting to herbicides. In fact, it is difficult to go to a local garden supply store without seeing shelves of products all promising to rid your lawn of weed problems quickly. Unfortunately, herbicides toxic to your weeds are often hazardous to you and other living things. Certain components of herbicides (i.e. 2,4-D and arsenic) are under scrutiny to determine if they pose serious health hazards. Many herbicides do not break down quickly but remain active in the soil, increasing both health and contamination risks.
If you cannot avoid using herbicides, look for the least toxic products and spot-treat affected areas only. Avoid products containing controversial chemicals, such as 2,4-D or arsenic. Look for formulations that break down rapidly in sunlight and by microbial action; such products do not leave chemical residues that can be tracked into the house. Unfortunately, many of the rapidly biodegradable solutions now available injures or kills all foliage, including your turf grasses. These products are appropriate only for spot-treating weeds in the lawn or for use along fence lines, walls, and other structures.
The Environmental Protection Agency (EPA) tests and rates the toxicity of all herbicides, and requires one of four warnings on all labels. From most toxic (I. DANGER and II. WARNING) to least toxic (III. CAUTION and IV. CAUTION). Words and ratings may vary for the same formulation depending on the degree of concentration. Use any herbicide–no matter how mild—with great care. Never use any herbicide when it is windy, and always follow label directions strictly. Look for herbicides made of naturally occurring products, such as fatty acids, that decompose quickly by soil microorganisms.
Do not—under any circumstances—increase the amount of herbicide kill to an area quicker. Not only is this irresponsible behavior, but you could receive a large fine from the Environmental Protection Agency (EPA).