| Abstract/Contents: | "Nineteen cultivars of bentgrass were evaluated for resistance to dollar spot disease at the Cambridge Research Station of the University of Guelph near Cambridge, Ontario. The species and their cultivars are browntop bentgrass (Agrostis capillaris): Egmont; Colonial bentgrass (Agrostis tenuis): Tracenta, Bardot, Allure; creeping bentgrass (Agrostis palustris): Cobra, SR 1020, Forbes 89-12, Carmen, Penneagle, Tamu 88-1, Providence, Emerald, National, Normarc 101, Putter, Penncross, 88.CBL, WVBP 89-D-15; and dryland bentgrass (Agrostis castellana): BR 1518. The plots were seeded at 2.2 g/m2 on 23 August 1990. Cultivars were arranged in a randomized block design of 1 m x 2 m plots, with 3 replications. The grass was maintained at a putting green height (7 mm). To ensure an even inoculum pressure, the fungus was applied to all plots. Inoculum was prepared by incubating 5 strains of the fungus, on autoclaved cereal grains (chicken scratch) for 2-3 weeks in mason jars. After drying overnight, the inoculum was chopped up in an Osterizer blender into small particles. The 5 strains of fungus were mixed together, and 2 g were evenly applied to each plot. Inoculum was first applied 21 June 1991 to initiate disease. Evaluations were made by weekly estimations until October 30, 1991. Analysis of variance on each week's data was performed using PROC ANOVA in SAS. When a significant cultivar effect was found in the ANOVA, mean separation was done with the test of least significant difference (LSD). Dollarspot disease incidence increased slowly up to July 24, after which, disease pressure was high for the next 13 weeks until 30 October. After the third week (July 24), there were statistically significant differences between the cultivars. Overall the cultivars Allure, Bardot, Tracenta, BR 1518 and Egmont showed the best dollarspot resistance throughout the 1991 field season. These are all the cultivars of species other than creeping bentgrass. The cultivars with the worst performance were: Carmen, 88.CBL, SR 1020, Forbes 89-12, Putter, and Emerald." |
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