Nematodes associated with grain sorghum in the Federal District, Brazil

Abstract

During May 1981 a nematode survey was conducted in an experimental area of Centro de Pesquisa Agropecuária dos Cerrados (CPAC), at Planaltina, Federal District, Brazil, where 25 genotypes of grain sorghum (Sorghum bicolor (L.) Moench were being agronomically evaluated. Four composite soil and root samples were collected from each genotype after harvest The nematodes were isolated from 100 g of soil and 10 g of roots using modified Coolen's method. Nine species of stylet bearing nematodes in their decreasing frequency of occurrence in samples were: Aphelenchoides sp. (100%), Ditylenchus sp. (100%), Tylenchus sp. (95%), Pratylenchus brachyurus (93%),  Aphelenchus avenae (90%), Helicotylenchus dihystera (68%), Meloidogyne javanica (37%), Paratrichodorus minor (13%) and Criconemella ornata (4%). The frequency of nematode occurrence between genotypes were: P. brachyurus, Helicotylenchus dihystera, Aphelenchoides sp., A. avenae, Ditylenchus sp., Tylenchus sp. (100%), M. javanica (92%), P. minor (11%) and C. ornata (4%). In general, the average nematode densities per sample were low, exception made Ditylenchus sp. and saprofitic nematodes, which were 99 and 288 respectively. Densities of C. ornata and P. minor were below one nematode per sample.