PHYTOPARASITIC NEMATODE POPULATIONS IN FESTUCA-ARUNDINACEA FIELD PLOTS IN SOUTHWESTERN MISSOURI

Field plots of tall fescue (Festuca arundinacea) at two locations on the same experimental farm in southwestern Missouri were sampled (one in 1987-88, the other in 1988-89) to inventory root-parasitic nematodes and to determine whether cultivars or endophyte (Acremonium coenophialum) infection frequencies (EIF) affected nematode population densities within single growing seasons. Plots were planted with seven tall fescue cultivars: Kentucky-31, Kenhy, Johnstone, Martin, Mozark, Missouri-96, and Forager. Kentucky-31 seed with high and low EIF were planted in separate plots. Plant-parasitic nematodes were extracted from soil samples, identified to genus, and enumerated four and three times per year for the 1987-1988 and 1988-1989 studies, respectively. Several plant-parasitic genera were identified from both fields, including Helicotylenchus, Heterodera, Hoplolaimus, Paratylenchus, Pratylenchus, Tylenchorhynchus, and members of genera grouped in the family Tylenchidae. Densities of five of these seven groups of nematodes differed among tall fescue cultivars in the 1987-88 study, but only two out of eight groups did so in the 1988-89 study. Irrespective of tall fescue cultivar, EIF had no consistent impact on nematode densities. The putative suppressive effect of endophyte infection on infection by plant-parasitic nematodes is not detectable within single growing seasons and deserves long-term study in field situations.