Influence of Irrigation and Heterorhabditis bacteriophora on Plant-parasitic Nematodes in Turf

Daily irrigated, 80% pan replacement, and nonirrigated field plots of Kentucky bluegrass (Poa pratensis L.) were inoculated with a mixture of Steinernema carpocapsae (All strain) and Heterorhabditis bacteriophora (HP-88 strain) in 1988. In 1989, daily irrigated and nonirrigated plots were inoculated with HP-88 alone. The turf and associated soil contained populations of Tylenchorhynchus dubius, T. nudus, Pratylenchus penetrans, Paratylenchus projectus, and Criconemella rustica. In irrigated plots in 1988, population densities of Tylenchorhynchus spp. were lower in plots inoculated with HP-88 plus All compared with that in control plots. The same effect was absent under nonirrigated conditions. In 1989, population densities of Pratylenchus penetrans associated with inoculated turf were lower than those recovered from noninoculated turf in irrigated but not under nonirrigated conditions. Population densities of plant-parasitic nematodes were generally higher in the irrigated compared with the nonirrigated environment.