Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/1995
Publication Date: N/A
Interpretive Summary: Several plant parasitic nematode species are known to reduce the establishment, growth, and productivity of certain rangeland grasses; nematodes extract a high percentage of energy from plant growth and reduce resistance of plants to drought, plant stress, and diseases by interfering with plant metabolic activity. A three year study determined seasonal population dynamics of three plant parasitic nematode species, and how populations are affected by environmental conditions. Soil water and temperature significantly (P < 0.05) affected the population trends of the ectoparasitic stunt nematode (Tylenchorhynchus acutoides) on crested wheatgrass cultivars Fairway (Agropyron cristatum) and Hycrest (Agropyron desertorum X A. cristatum), Rosana western wheatgrass (Pascopyrum smithii), Oahe intermediate wheatgrass (Thinopyrum intermedium), and the RS-1 hybrid (quackgrass, Elytrigia repens X bluebunch wheatgrass, Pseudoroegneria spicata). The migratory endoparasitic nematode, P. neglectus was less affected by temperature and soil water than were ectoparasitic nematodes X. americanum and T. acutoides. Nematode reproduction was greatest in P. neglectus and T. acutoides.
Technical Abstract: The effects of environmental conditions on population trends of plant parasitic nematodes were studied in experimental plots of five wheatgrasses in the western Utah desert. Soil water and temperature affected the population trends of the ectoparasitic stunt nematode, Tylenchorhynchus acutoides, the ectoparasitic dagger nematode, Xiphinema americanum, and the migratory endoparasitic lesion nematode, Pratylenchus neglectus, on Fairway crested wheatgrass, Agropyron cristatum; 'Hycrest' crested wheatgrass, A. cristatum X A. desertorum, 'Rosana' western wheatgrass, Pascopyrum smithii; 'Oahe' intermediate wheatgrass, Thinopyrum intermedium; and RS-1 hybrid (Elytrigia repens X Pseudoroegneria spicata, in a three-year field study (1984-86). The largest soil populations were collected in 1984 under good plant growth conditions. A reduction in nematode populations occurred in 1985 and 1986 apparently because of low soil-water conditions. There was a positive relationship between high soil-water and maximum population density peaks of T. acutoides in the spring and fall of 1984, and low soil water and minimal population densities of the nematode in 1985 and 1986. Pratylenchus neglectus populations were affected by soil water, although to a lesser degree than the ectoparasitic nematodes. Nematode population densities were significantly lower in 1985 and 1986 than in 1984. Higher nematode populations were found in the spring on the earlier-maturing cultivars Hycrest and Fairway. Maximum populations occurred later in the season at a lower soil depth.