A survey of plant-parasitic nematodes associated with cotton in northeastern louisiana.

A survey was conducted in northeastern Louisiana to determine the frequency and abundance of plant-parasitic nematodes associated with cotton. In fall 1997 and 1998, more than 600 soil samples were collected from cotton fields representing 6,200 ha, which is 5.3% of the cotton production hectarage in this region. Composite soil samples were collected from 10 ha in each field. Nematodes were extracted by gravity screening and sucrose centrifugation, identified to genus, and quantified. Nine genera of plant-parasitic nematodes were identified. Rotylenchulus reniformis was found in 67% of the fields sampled, with an average population of 12,959 juveniles and vermiform adult stages per 500 cm(3) of soil. Meloidogyne incognita was identified in 25% of the fields sampled, with an average population of 998 juveniles per 500 cm(3) of soil. Hoplolaimus spp. were identified in 3%, or 155 ha, with an average population of 282 juveniles and adult stages per 500 cm[sup3] of soil. Rotylenchulus reniformis and M. incognita occurred at population levels above reported economic thresholds in 49% and 21% of the fields, respectively.