| Abstract/Contents: | "There were two experiments in this study, which was conducted at the Valentine Turfgrass Research Center, University Park, PA, on perennial ryegrass maintained under golf course fairway management conditions, and mowed three times per week at 0.5 inch cutting height. The soil was Hagerstown silt loam with a soil pH of 7.0. Dimension 1EC (1.0 fl oz/1000 sq ft) was applied on 1 May for control of crabgrass. The experimental area was fertilized on 18 May with 1.0 lb nitrogen (Scotts 18-9-18) per 1000 sq ft, 5 Jun with 0.5 lb nitrogen (Lebanon 28-7-14) per 1000 sq ft, and on 29 Jun with 1.0 lb nitrogen (Country Club 18-5-9) per 1000 sq ft. Fungo 4.5F and Dyrene 4F were applied at 2.0 and 8.0 fl oz, respectively, per 1000 sq ft on 23 Jun, and Lesco Benomyl 50WP (2.0 oz/1000 sq ft) on 3 Jul for control of brown patch. Treatment plots, 3 ft x 7 ft, were arranged in a randomized complete block design with three applications. In both experiments, fungicides were applied on turf area on 7 Jul, with a CO₂-powered boom sprayer, using TeeJet 8004 nozzles, at 40 psi, in water equivalent to 2 gal per 1000 sq ft, except as noted in table. On 9 Jul, 2 days after treatment (DAT), turf in the first experiment was enclosed in a polyethylene greenhouse and inoculated with a 6-isolate pool of Pythium aphanidermatum. An internal intermittent misting system provided continuous high relative humidity. The greenhouse was vented during the daylight hours to maintain a temperature range of 85^DDEG to 95^DDEGF. Vents were closed during the night. On 15 Jul (8 DAT), disease severity was assessed. On 14 Jul (7 DAT), the turf area of the second was enclosed in a polyethylene greenhouse, inoculated with a 6-isolate pool of P. aphanidermatum, and was maintained as described above for the first experiment. On 19 Jul (12 DAT) disease severity in the second experiment was assessed. Data were subjected to analysis of variancem and the mean values were separated using Duncan's New Mutiple Range Test (P=0.05). In the experiment (8 DAT), the Banol and Heritage combination treatment, each of the three rates of BAS 500F, Heritage, Banol (in water equivalent 2 gal per 1000 sq ft), and Subdue Maxx were providing excellent control of Pythium foliar blight. In the second experiment (12 DAT), none of the fungicides provided satisfactory control; however, disease severity in the two Banol treatments and the Sundue Maxx treatment were significantly different from all other treatments. It should be noted that following inoculation, conditions in the greenhouses, such as continuous leaf surface wetness, high relative humidity, and warm temperature, were highly conducive for infection by P. aphanidermatum, and subsequent disease development in these experiments. Therefore, the disease severity was extremely high, as indicated by the untreated check plots, throughout the experiments." |
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