Weeds are a constant headache for gardeners. Hand pulling weeds takes a long time and can cause some serious back issues. The use of herbicides reduces the amount of work required for the removal of weeds. Herbicides come in both selective and nonselective varieties. While selective herbicides kill specific weed types, nonselective herbicides serve a different purpose.
Nonselective herbicides are not weed specific. Any plant that the herbicide touches is often killed or damaged. Nonselective herbicides are often only used for the removal of large patches of vegetation, where saving certain plants is not an issue. Nonselective herbicides are never used in turf because they kill grass. The herbicide is either systemic or contact.
Contact herbicides create localized damage to the weed where it makes contact with the plant. Contact herbicides, says the University of Rhode Island, are best used against annual weeds. Contact herbicides only kill the part of the plant that the herbicide comes in contact with. If the damage is enough, the herbicide will kill the weed.
Systemic herbicides are effective against both annual and perennial weeds. Systemic nonselective herbicides attack the entire plant by moving through its body. It disrupts photosynthesis and breaks down the cells of the plant. The plant will twist and wilt as well as lose color.
Soil sterilant nonselective herbicides have special characteristics. Unlike most nonselective herbicides that are limited to how far the liquid penetrates the soil, soil sterilant nonselective herbicides turn into gases once active and penetrate the soil. Soil sterilants are often sold as soil fumigants.
Nonselective herbicides are damaging to landscape plants and desirable garden plants when misapplied. Herbicides are never applied when it is windy or rainy outside. Blowing of the herbicide in the breeze will cause contact with desirable plants. Rain will cause the herbicide to drain to areas it is not wanted. Herbicides are applied according to the application rate suggested on the packaging.