| A two-year survey was conducted to determine the ecology of plant-parasitic nematodes and their antagonists on golf course greens turf in southern New England. Soil samples were collected from three greens each at 38 golf courses, for a total of 114 samples. Samples were collected in May, July, and September of each year. Nematodes were extracted from soil samples, identified to genus and counted. Genus diversity and seasonal fluctuation of nematode populations, both within each season and between the two sampling years, were analyzed. Additionally, data on soil physical and chemical properties, as well as management practices on each golf course were collected. These data were correlated with nematode population levels. Surveys for fungal and bacterial nematode antagonists were also performed, both visually and using molecular methods. The data showed that there were differences in numbers of phytoparasitic nematodes between golf courses. The main genera of nematodes recovered from the samples were Tylenchorhynchus, Helicotylenchus, Criconemella, Hoplolaimus, and Heterodera. Population levels of plant-parasitic nematodes were significantly higher in the 2004 season than in 2003. Abundance of Tylenchorhynchus nematodes was highest in the summer, while that of Criconemella, Helicotylenchus, and Heterodera were highest in the fall sampling date. Total plant parasitic nematode populations were positively correlated with age of the greens, percent Poa annua invasion, organic matter content, mowing frequency, phosphorous, and zinc. Negative associations with total plant parasitic nematode populations were observed with fine sand percentage and height of cut in 2003, and nickel in both years. Nematode antagonists were not successfully recovered or identified from DNA extracted from soil samples. However, the bacterium Pasteuria penetrans was observed microscopically on Tylenchorhynchus nematodes. There were significantly more Pasteuria-infected nematodes in the fall sampling than in the summer. Infection by P. penetrans was not correlated with nematode populations, suggesting that food source availability may have been plentiful enough to allow for sufficient reproduction in spite of bacterial infection. Levels of P. penetrans were also not correlated with any of the soil factors or management practices studied. Nematode-destroying fungi were not observed in or identified from any of the soil samples. |
