Sucker-Stopper RTU is made from the plant growth regulator napthaleneacetate (NAA). This product is widely used in commercial agriculture to prevent suckers and as a thinning agent on fruit trees. Simply spray to control sprouts and sucker growth on apples, olives, pears, non-bearing citrus and ornamental woody plants. Be sure to treat before new growth suckers are 10 inches in length. The earlier you treat, the better. Control should last about 3 months.