Pythium spp. and ring nematode populations from overseeded hybrid bermudagrass golf greens

Three golf greens on each of five golf courses in central Alabama were sampled every 4–5 weeks from December 2000 through November 2001. Each golf green was divided into four quadrants and seventeen, 8 mm diameter, 2.5 cm deep soil cores were removed from each quadrant, bulked, and plated on a Pythium selective agar medium. Air and soil temperature, soil moisture, relative humidity and pH data were also collected. Colonies of Pythium were enumerated after 48 and 60 hours of incubation. Each month, four random Pythium colonies were selected from each green to be identified. Four months were chosen for identification based on temperature differences. Isolates of Pythium were grown on grass water cultures, and identified after 3–7 days. From bulked soil samples, 50 cc of soil were processed by a combined sieving and sugar flotation method. Ring nematode numbers from each green and sample date were counted with a stereomicroscope. Data were analyzed by PROC CORR from SAS Version 8.; Soil temperature, percent organic matter, carbon, silt, golf course age, and ambient air temperature prior to sampling were all negatively correlated to Pythium spp. colony forming units (cfus). Percent sand and precipitation were positively correlated to cfus of Pythium spp. Results from this research could aid in creating a disease monitoring program for Alabama golf courses.; Eight species of Pythium were most isolated from golf greens throughout the year. These included: P. catenulatum, P. graminicola, P. irregulare, P. pulchrum , P. rostratum, P. torulosum, P. ultimum var. ultimum, and P. vanterpoolii . Isolates of P. torulosum accounted for 24% of all isolates, while P. rostratum, P. ultimum and P. vanterpoolii accounted for 35, 16 and 14% of all isolates respectively. Greenhouse pathogenicity studies could determine which species can cause disease on Poa trivialis, bermudagrass, and Poa trivialis and bermudagrass grown together.; Soil acidity (pH), Pythium spp. cfus, and percent sand were negatively correlated to ring nematode numbers. However, soil temperature, ambient air temperature prior to sampling, percent organic matter, carbon, and silt, and golf green age were positively correlated to nematode counts. Ring nematode numbers increased as golf green age increased, and decreased as soil temperature increased. Future studies could consider the role that nematodes and Pythium play together on disease development and severity.