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 field s representing 6,200 ha, which is 5.3% of the cotton production hectarage i n this region. Composite soil samples were collected from 10 ha in each fie ld. Nematodes were extracted by gravity screening and sucrose centrifugatio n, identified to genus, and quantified. Nine genera of plant-parasitic nema todes were identified. Rotylenchulus reniformis was found in 67% of the fie lds sampled, with an average population of 12,959 juveniles and vermiform a dult 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 cm3 of soil. Hoplolaimus spp. were identified in 25% of the fields samp led, with an average population of 998 juveniles per 500 cm(3) of soil. Hop lolaimus spp. were identified in 3%, or 155 ha, with an average population of 282 juveniles and adult stages per 500 cm(3) of soil. Rotylenchulus reni formis and M. incognita occurred at population levels above reported econom ic thresholds in 49% and 21% of the fields, respectively.