| Abstract: | A study was conducted to determine the vertical distribution of Tylenchorhynchus nudus, Criconemella curvata, and Helicotylynchus cornurus in the upper 5 cm of bentgrass (Agrostis palustris cv. Penncross) putting green turf. The effect of fenamiphos on the vertical distribution of these species also was examined. Experimental design was a split-plot in which whole-plots were fenamiphos treated (0.11 kg a.i./100 m²) or untreated, and sub-plots were two strata (depths of 0-2.5 crn and 2.5-5.0 cm). Soil samples were collected during the growing season for 2 years after treatment to determine root weight and number of nematodes. Root weight was greater in the upper stratum on all sampling dates in both years. When differences between strata in population density were observed, T. nudus, C. curvata, and H. cornurus were more concentrated in the upper stratum. Vertical distribution of T. nudus, C. curvata, and H. cornurus was similar to the distribution of root weight. The difference in population density of H. cornurus between upper and lower strata was affected by fenamiphos on some dates, whereas differences between strata were unaffected for T. nudus and C. curvata. Double arcsine transformed proportions of the total populations of T. nudus, C. curvata, and H. cornurus in the upper stratum on each sampling date indicated no differences between fenamiphos treated and untreated plots in 1989 or 1990. |
