Integrating host resistance and fungicide for control of dollar spot on creeping bentgrass

Integrated effects of genetic host resistance and fungicide (chlorothalonil, Daconil Ultrex 82.5WG) for controlling dollar spot were evaluated on three modern creeping bentgrass (Agrostis stolonifera L.) cultivars, including Independence, Penncross and Declaration. During 2011 and 2012, four runs of 21-day period resistance experiments and two runs of season long threshold experiments were conducted. The resistance experiment consisted of a single Daconil Ultrex 82.5WG application at rates of 0, 1.675, 3.35, 5.025, 6.7, 8.375 kg a.i. ha-1 to three replications of each cultivar. The threshold experiment consisted of multiple Daconil Ultrex 82.5WG applications at the rates of 0, 4.31 and 8.62 kg a.i. ha-1 based on predetermined application thresholds to six replications of each cultivar. Both experiments showed that the Declaration can ahiceve a better dollar spot control than the other two cultivars with less fungicide applications. We also attempt to quantify host resistance in terms of the amount of fungicide required to achieve a given level of control had mixed results