Efficient chemical control of dollar spot on bentgrass turf

Abstract

Dollar spot disease caused by Sclerotinia homoeocarpa is recently recognized in Japan as one of the serious diseases of bentgrass putting greens in golf courses. This study was conducted to survey fungicides which could efficiently control the diseases and low in fish toxicity. The results obtained are summarized as follows:
(1) Based on the experiments of antifungal activity to 5 isolates of the pathogen on PDA, iprodione, procymidone and vinclozolin were found to be a potent active chemicals (ED₅₀ less than 1 ppm) with low fish toxicity (TLm 48 more than 10 ppm) .
(2) These three chemicals completely controlled the disease development on penncross bentgrass sods grown in pods at 25°C by single application before inoculation with 3 isolates obtained from different districts.
(3) Field investigations on penncross bentgrass turf in spring and summer seasons demonstrated that the dollar spot patches disppeared by single application at doses 0.25 and 0.5g/m² of procymidone and vinclozolin. The application of iprodione at 0.23g/m², however, seemed to be effective only when it was applied before or at the early stage of disease development.