Effect of clipping on control of "alho-macho" (Sisyrinchium platense Johnst.)

"Alho-macho" (Sisyrinchium platense Johnst.) is a native plant occurring on natural pasture at the southwestern region of Rio Grande do Sul, Brazil, o n heavy clay black soils with poor drainage, specially when these were modi fied by cultivation. In these grassland areas livestock breeding, alone or associated to agriculture, have a great economic importance. Cattle do not graze S platense, and the natural desirable plants are usually replaced by this species and may restrict the potencial gains in animal production. Aim ing to evaluate the effects of clipping once, twice and four times in contr olling this plant, an experiment in a randomized complete block design was carried out in two geographical situations of a natural pasture, during thr ee years. The results showed a decrease mean of 55% on foliage cover of "al ho-macho" when clipping once, twice or four times on wet areas. In dry area s the decrease on foliage cover mean was 30,7% when clipping once or twice.