Another day, another dollar

Photo of creeping bentgrass cv. 007

Creeping bentgrass cv. 007, amended with municipal waste compost at establishment (left) and biochar at establishment (right). We observed no difference between the fertility treatments for seasonal dollar spot suppression.

Dollar spot (Sclerotinia homoeocarpa F.T. Bennett) is a common disease of turfgrass worldwide. Even with adequate fertility and deployment of cultural controls, multiple fungicide applications typically are required for control. While organic amendments are considered promising alternative management tools, we need to understand the impact of these products when used alone or when combined with fungicides.

Fertility and fungicide source were evaluated for impact on dollar spot on a newly established creeping bentgrass (Agrostis stolonifera L. cv. 007) fairway. We applied main-plot treatments as a compost (Orgro, Baltimore City Composting Facility, Md.) and a biochar (CarbonizPN Soil Enhancer, Mirimichi Green, Castle Hayne, N.C.) applied at establishment or as a bi-annual topdressing, a vermicompost (MicroBac, Southern Organics & Supply, Monroe, N.C. plus Vermaplex, Monroe Works, Archer, Fla.) plus conventional fertility (sulfur-coated urea, triple superphosphate and potash), conventional fertility and none. We standardized nitrogen fertility levels for all treatments at approximately 3.75 lbs. of nitrogen per 1,000 sq. ft. annually. We applied sub-plot treatments as a 14-day contact Secure (fluazinam, Syngenta Crop Protection), or penetrant Xzemplar (fluxapyroxad, BASF), threshold contact or penetrant and none. Threshold treatments were made when more than two infection centers were counted on two of four replicates.

In year one of the study we observed no difference between fertility-source impact on seasonal dollar spot suppression, as all fertility sources were significantly better at controlling dollar spot than our non-fertilized check. All fungicide treatments effectively reduced dollar spot when applied at designated 14-day intervals. When considering threshold-based fungicide applications, the vermicompost plus conventional fertility treatment provided the longest duration of control for both contact and penetrant fungicides.

Cody Beckley and Joseph Roberts, Ph.D., are at the University of Maryland. You may reach Cody Beckley at for more information.

Photo: Joseph Roberts

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