Use of cover crops as a tool in the management strategy of sourgrass

Abstract

The use of cover crops with potential to reduce the development of weeds in crops may represent an important tool in an integrated weed management. To do so, work to evaluate initial development of Digitaria insularis under cover crops residues on the soil surface was conducted in the 2014/2015 crop in a greenhouse. The experimental design was in randomized blocks in a (7x4) + 1 factorial arrangement, and the factors consisted in seven species of cover crops (Pennisetum glaucum, Crotalaria spectabilis, Fagopyrum tataricum, Urochloa brizantha cv. Piatã, Cajanus cajan, Eleusine coracana and Mucuna pruriens) and four levels of dry phytomass (4, 8, 12 and 16 Mg ha^-1) plus the control treatment without cover crops, with four repetitions. M. pruriens, C. cajan e U. brizantha stood out in the suppression of D. insularis, and 4 Mg ha^-1 of dry phytomass of these species were sufficient to promote an expressive reduction in the total number of plants emerged, germination speed index, dry phytomass of the shoots, leaf area, dry phytomass and root volume. For these species, from 8 Mg ha^-1 of phytomass development of D. insularis was no longer detected. As for the other species, the control of D. insularis was efficient only with high amounts of phytomass (16 Mg ha^-1). D. insularis was highly sensitive to the presence of residues on the soil surface, making cover crops cultivation an important tool for the integrated management of this species.