| Abstract/Contents: | "A survey was conducted to document management practices, agrichemical usage, foliar symptoms, pH, percent moisture, soil texture, and plant parasitic nematode communities in urban turf ecosystems. To date, 105 lawns in East Baton Rouge Parish have been sampled. A total of 11 nematode genera were identified from soil and root samples of St. Augustine lawns; Criconemella have been found in 93%, Gracilicus in 1%, Helicotylenchus in 92%, Hemicycliophora in 1%, Hoplolaimus in 1%, Meloidogyne in 64%, Pratylenchus in 31%, Scutellonema in 1%, Tylenchorhynchus in 29%, Tylenchus in 98% and Xiphinema in 21%. Respectively, average nematode densities per 250cc of soil were 118, 20, 208, 11, 12, 51, 34, 11, 34, 128, and 11. A total of 10 nematode genera were identified from soil and root samples of centipede lawns; Criconemella have been found in 100%, Helicotylenchus in 88%, Hoplolaimus in 35%, Meloidogyne in 35%, Pratylenchus in 82%, Scutellonema in 1%, Trichodorus in 12%, Tylenchorhynchus in 18%, Tylenchus in 100% and Xiphinema in 18%. Respectively, average nematode densities per 250cc of soil were 286, 277, 22, 17, 63, 25, 9, 37,129, and 14. The pH of the soils from St. Augustine lawns ranged from 5.1 to 6.9, with an average of 6.2. Centipede soil pH ranged from 6.1 to 7.3, with an average of 6.5. Percent soil moisture ranged from 7.7% to 25% with an average of 17.4% for St. Augustine and from 5.8% to 20.6% with an average of 15.4% for centipede. Soil temperatures during the summer ranged from 26.48C to 34.38C, with a sharp decline to 208C in the fall. Using the soil hydrometer method of soil classification, types range from clay (50%+ clay content) to sandy clay loam (60% sand, 13% clay, 26% silt), to silt loam (10% sand, 11% clay, 79% silt), with the average being loam (30% sand, 20% clay, 50% silt). The most prevalent nematodes, ring, spiral, stunt, and lesion, have been isolated and established in axenic cultures for use in greenhouse pathogenicity trials. Microplot trials, currently in progress, will evaluate the impact of soil type on nematode reproduction and pathogenicity on these two grass species. Treatments in microplot trials include three soil types (clay loam [35% sand, 34% clay, 31% silt], sandy loam [70% sand, 13% clay, 17% silt], and sandy clay loam [55% sand, 22% clay, 23% silt]), three nematode community infestation levels (0, 1000 and 10,000 nematodes) and two grass species (St. Augustine and centipede). Soil will be infested with nematodes two weeks after transplanting 10 cm square sod pieces into microplots. Grass will be cut to a height of 2 cm every two weeks, and clippings will be dried and weighed. Soil subsamples will be collected monthly to evaluate nematode reproduction." |
|---|
