Methods of controlling sapé in molasses grass pastures

Abstract

Sapé (Imperata brasiliensis Trin.) is a perennial plant spreading by rhizomas and seeds, and constitutes a serious invader of molasses grass (Melinis minutiflora, Beauv.) pastures in the Zona da Mata of Minas Gerais State. Considering ways to deal with it, a pasture-renovation experiment was carried out in which the primary treatments were the application of a herbicide (41% A.I. at a rate of 41/ha), ploughing or burning. These were followed by seeding either with molasses grass, of 12% germination at a rate of 15 kg/ha, or with Brachiaria decumbens, of 60% germination at a rate of 4 kg/ha. The sowings were made with and without fertilizer, at a rate of 500kg of a 4-14-8 commercial mixture. These alternatives made up 12 treatment combinations of e 3 x 2 x 2 complete factorial, laid out in a randomised block design with three replications. The results indicated that burning was the least efficient way of controlling sapé. The most efficient and economic treatment, in terms of estimated replacement of the invader by desirable species, per unit cost, was ploughing followed by seeding with Brachiaria decumbens without fertilizer.