Chemicals That Kill
Most brush killers available to homeowners contain triclopyr, glyphosphate, or both. Triclopyr kills most broadleaf plants, including woody plants, but usually does not affect grasses or grass-type plants. Glyphosphate is a non-selective herbicide that kills any plant with which it comes into contact. Both are absorbed through the foliage of plants, or through freshly cut stems or trunks. Triclopyr may also be taken up through the roots. Brush killers are available as concentrates, which are usually mixed with water and applied with a tank or hose-end sprayer to large plants or over-large areas. Ready-to-use brush killers typically are not as strong as concentrate mixtures and are better suited to use on small areas or spot treatments.
Wet and Kill
The foliar spray method is the best way to eradicate large areas of small and medium-size brushy plants. Use a tank or hose-end sprayer to lightly coat the leaves of unwanted plants with brush killer. For a single plant or one in a flowerbed, use a sponge, paintbrush, or specialty spreader to coat the leaves with the herbicide. Try to coat the upper and lower sides of the leaves with the spray or liquid, but not to the point that it runs off. Both methods can also be used on brush that has been cut or mowed down by treating the cut stems and trunks.
Cut and Kill
The cut-and-kill method can be used to get rid of any size brush, including shrub and tree seedlings. Cut the unwanted plant off level, as close to the ground as possible and brush off sawdust and other debris. Within four hours, spray or wipe undiluted brush killer on the stump. To kill large tree stumps, apply the herbicide just inside the bark where the living tissue is located.
Kill and Cut
The basal bark method works faster than the cut-and-kill method to get rid of trees that are smaller than 6 inches in diameter. Oil-soluble brush killer is used to coat the bark of the tree. The oil breaks down the waxy substance in the bark so that the herbicide can pass into the living tissue. A homeowner can mix any brush killer with penetrating oil or can buy a pre-mixed product. Another method, called the hack and squirt, is better for trees larger than 6 inches in diameter. After cutting slits into the tree every 2 inches around the trunk, squirt undiluted brush killer into the cuts. The cuts should be level or slanted down into the tree to prevent the herbicide from running out. The dead brush can be left standing or removed after it is completely dead.
Use With Care
Wear gloves, long sleeves, and long pants when applying brush killer. Do not get it on your skin, in your eyes, or inhale fumes or spray. Wash any exposed skin immediately after applying brush killer; do not eat, drink, or smoke until you wash your hands. Wash contaminated clothes separately from other laundry. Do not apply brush killer on a windy day and do not allow drift or liquid to contaminate desirable plants. Do not contaminate drains, sewers, waterways, or other bodies of water.