Variabilidade espacial de fitonematoides em área de cultivo de feijoeiro após erradicação de goiabeiras

Abstract

One of the main limiting factors for agricultural production is the plant parasitic nematodes, particularly Meloidogyne and Pratylenchus, because they parasite important crops causing high economic losses. Their control is very complex, after introduction, these nematodes cannot be eradicated. Therefore, understanding how management practices affects nematode community structure and the spatial variability of their populations will improve effectiveness of long term measures. This work had as objective to evaluate variations on plant-parasitic nematodes structure and spatial distribution and cultivation area of cowpea after guava orchard eradication. The study was carried out at Nossa Senhora do Rosário Farm in Pesqueira municipality in Pernambuco State. Soil and roots samples were collected in 2012 and 2015, in a 10×10-m mesh with 64 points, being data submitted to Geostatistical analysis. Before guava eradication, only Meloidogyne in soil presented high level of spatial dependence, fitting to exponential model. After cowpea cultivation, each Pratylenchus and Helicotylenchus populations turn to high level of spatial dependence in soil, with the exponential model as best fit, as well the bacterivorus, particularly Rhabditidae, except Gaussian model fitted best. Meloidogyne density in soil was low showing no spatial dependency, in contrast to roots, where Meloidogyne spatial dependency was moderate, fitting to spherical model. In both periods, the range of all nematode genera was longer than 10 m. The use of a non adequate management, as the introduction of a susceptible host, as cowpea, increased density and dissemination of important plant parasitic nematodes in the field.