Sequência de cultivos no manejo da casca preta do inhame em campo

Abstract

Among the constraints to yams (Dioscorea spp.) production in Brazil, the dry rot disease caused by the nematodes Scutellonema bradys, Pratylenchus coffeae and P. brachyurus is the most important. The objective of this study was to evaluate the efficacy of cropping sequence on a mixed population of Scutellonema bradys and Pratylenchus coffeae, in naturally infested field aiming to reduce the population density of these species and turn feasible the yam cropping in the area. A field experiment was carried out in Quebrangulo county (Alagoas state, Brazil) in two consecutive years in a randomized block design with 14 treatments and three replications. Prior to planting, soil composite samples were collected in each plot to determine the initial nematode population densities. In the first year, the treatments were constituted of plots grown with Zea mays „BR 106‟, Pennisetum purpureum „Roxo‟, Brachiaria humidicola, Digitaria decumbens „Pangola‟, Manihot esculenta „Rosinha‟, Ipomoea batatas „Sergipana‟, Vigna unguiculata „Corujinha‟, Phaseolus vulgaris „Mulatinho‟, Canavalia ensiformis, Crotalaria juncea, C. ochroleuca, C. spectabilis, Phaseolus lunatus „Branca‟ and Dioscorea cayenensis „Inhame-da-Costa‟. At the end of the growth cycle, soil and root samples were collected to assess nematode population densities. In the second year, all experimental area was planted with yam and after nine months the tubers were harvested and determined tuber weight/plot, dry rot incidence and nematode densities for both soil and tuber samples. The highest production of healthy yam tubers was recorded on plots previously planted with Crotalaria spp. and P. lunatus.