Early Dollar Spot on Golf Courses This Year – Turfgrass Science at Purdue University

Early Dollar Spot on Golf Courses This Year

If you’re lucky enough to be in the areas of Indiana that have received ample rainfall, you are unfortunately starting to see dollar spot. The excess rain in parts of the state triggered rapid plant growth and infrequent mowing, which in turn forced clipping removal and removal of N from the system. The N in the system may have been further depleted with leaching rains. Ample soil moisture, elevated soil temperatures (ranging between 60 F and 70 F at 3 inch depth in West Lafayette) and high humidity favor dollar spot development, which is most severe on N-deficient turf. The standard May fertilization of 0.75-1.0 lb N/1000 sq. ft. with primarily slow release N should help to minimize dollar spot now. On golf courses with a long history of dollar spot, first and foremost review the fertilization practices and increase the annual N if possible. Other cultural practices to reduce dollar spot include early morning rolling, syringing and/or mowing to minimize free water on the leaf surfaces. It makes sense to use fungicides early in the season at or before the first outbreak, rather than waiting for symptoms to become obvious. Although this seems to conflict with typical IPM strategy to apply only after symptoms approach an intolerable threshold, we feel early applications will suppress inoculum levels, thus limiting disease pressure and reducing fungicide use over the whole season. If you choose to apply early (or whenever you apply fungicides for that matter), be sure to rotate fungicides and to tankmix systemics (acropetal penetrants) with contact fungicides to help minimize the resistance risk.

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