To control the root-lesion nematode (Pratylenchus brachyurus), some strategies have been recommended with the aim of reducing the population levels and others, with the aim of stimulating root development; thus, the aim of this study was to identify the benefits of interactions among cover crops, organic matter content and planting systems. The two chosen areas had natural infestation with the nematode, and the cover crops Crotalaria spectabilis, Pennisetum glaucum (pearl millet ADR 300), Brachiaria decumbens, corn ('Formula' hybrid), were established, as well as treatments with and without chemical weed. The control was the fallow (periodic weed). Cover crops were planted on 22/2/2010 and the soybean was sown on 3/11/2010. Each assay included plots of 6 m and 10 rows (0.45 m spacing). The adopted design was in randomized blocks, with 4 replicates. As subplots, we used direct and conventional planting of soybean and cover crops by means of a large harrow. Evaluations consisted of cover crop dry mass, nematode population levels, root fresh mass, shoot dry mass and grain yield. According to the obtained results, the soil organic matter had benefits and a decrease in P. brachyurus multiplication; moreover, there was an interaction with the cover crop and the planting method. Conventional planting reduced the infection levels at the evaluations up to 40 days after emergence (40 DAE); in the subsequent evaluation (70 DAE), however, the levels for direct planting were lower, evidencing positive attributes of this planting technique. Among cover crops, C. spectabilis showed greater antagonism to P. brachyurus. Control weed and chemical weed prevented the multiplication, but the nematode was maintained at sufficient levels to cause damage.
root lesion nematode; crop management; population dynamics
