Dollar spot diameters were also measured weekly in centimeters on three dollar spots per bentgrass clone for 10 wk.
The dollar spots of the resistant clones rarely coalesced to form large dollar spots (personal observation).
DOLLAR SPOT is a major disease that affects the performance of creeping bentgrass on golf greens, tees, and fairways.
Many of the control strategies currently available are not completely effective for dollar spot disease suppression.
Disease resistance mechanisms including dollar spot resistance are not currently understood in turfgrasses.
The mechanisms of dollar spot resistance in creeping bentgrass have not been evaluated.
The objectives of this study were to: (i) evaluate dollar spot disease resistance of 265 collections of creeping bentgrass in two locations; (ii) determine bentgrass clone stability of dollar spot resistance; and (iii) evaluate 10 resistant and susceptible clones for percentage green turf cover, dollar spot diameter size, turf density, stomate density, and trichome number and size to determine if any of these characteristics are associated with disease resistance.
Dollar spot symptoms appeared 2 wk following inoculation, and plants were rated every week for a total of 13 wk during the growing season on a 1-to-9 scale: 9 = 0 to 5% diseased turf, 8 = 10% diseased turf, 7 = 15 to 25% diseased turf, 6 = 30 to 40% diseased turf, 5 = 40 to 50% diseased turf, 4 = 60 to 71)% diseased turf, 3 = 75 to 85% diseased turf, 2 = 90% diseased turf, and 1 = 95 to 100% diseased turf.
Plant characteristics such as stomate density, trichome number, and trichome size, for most cases, were measured on the same 10 resistant and 10 susceptible clones; however, in some cases susceptible clones were replaced with other susceptible clones because of deatb from dollar spot.
Dollar spot disease data was subject to ANOVA with a split-plot in time model (Bonos et al.
Turf density, percentage green turf cover, dollar spot diameter, stomate density, and trichome number and length were subject to ANOVA by location.
Stability Analysis Of the 265 clones evaluated in the ANOVA, only 2% maintained significant dollar spot resistance with dollar spot disease average ratings [greater than or equal to] 6.