Nematode community structure in dogwood, maple, and peach nurseries in Tennessee

Tennessee nurseries are major suppliers of ornamental and fruit trees, but the potential for nematode-induced losses is poorly known. This study was undertaken to i) compare populations of nematode trophic groups in dogwood, maple, and peach nurseries; ii) identify and determine the diversity of of plant parasitic nematodes in these areas; iii) determine the relative importance of tree species and age class, weed cover, and edaphic factors in the distribution of plant parasitic species. Ninety-two nursery blocks were sampled for nematodes in March, July, and October, 1981. Each soil sample was analyzed for pH, bulk density, texture, and organic matter content. Nematodes were extracted from a 200 cm³ aliquant of each sample and counted. Microbi- vores, fungivores, predators, and "omnivores" (trophism unknown) were counted as such, but plant parasites were identified to species. Microbivores occurred in the highest numbers for all sampling dates, followed by plant parasites, fungivores, "omnivores" and predators. Fifty-eight plant parasitic species in 25 genera were identified, with one to sixteen species occurring in each site. Diversity was higher in March and Octo-than in July, higher in maple than in dogwood and peach blocks, and posi-tively correlated with percent weed ground cover and number of weed spe-cies in July. Paratylenchus projectus and Xiphinema americanum were the two most common species, occurring in 88% and 77% of the sites, respec-tively. A community ordination technique was employed to determine simi-larities among sites based on plant parasitic nematode communities.