Golfdom, December 2011

S PRACTICAL RESEARCH DIGEST FOR TURF MANAGERS IN THIS ISSUE OUR SPONSORS www andersonsinc com 800 537 3370 www fmc com 800 321 1FMC T H E P R O M I S E O F C O M P O S T I N G PART 2 IN A SERIES Alternative Approaches to Manage Dollar Spot O ver the last 40 years fungicides have been the most widely used tool for managing dollar spot S homoeocarpa As a result of numerous applications of fungicides during a growing season resistance of S homoeocarpa has led to an ongoing challenge of fewer fungicides being available to control the disease S homoeocarpa has developed resistance to several classes of fungicides including heavy metal based compounds contact fungicides and systemic fungicides such as dicarboximides benzimidazoles and demethylation inhibitors DMI Ki Jo 2008 Resistance of S homoeocarpa to certain benzimidazole fungicides like Cleary 3336 and Chipco 26019 two commonly used older fungicides for dollar spot control have been reported Vargas et al 1992 Ki Jo et al 2008 Resistant strains to these particular fungicides were found to have persisted for more than 20 years on some golf courses The development of resistance to the DMI fungicides like Bayleton and Rubigan occurred much slower compared to the benzimidazole fungicides In some cases the benzimidazole fungicides developed resistance in one to two years after the products were used whereas most of the DMI fungicides had been used for more than ten years before resistance was confirmed In most cases S homoeocarpa exhibits cross resistance i e resistance to more than one fungicide within the same chemical group or multiple resistance i e resistance to different fungicide classes Although fungicides have been successful for dollar spot management in the past increasing levels of fungicide resistance coupled with tightened environmental scrutiny of existing fungicides has left fewer chemical options for controlling this pathogen Therefore turfgrass managers are looking for effective alternative disease suppressive practices that may help delay the occurrence of fungicide resistance www turfgrasstrends com December 2011 TURFGRASS TRENDS 29 or extend their effectiveness Incorporating natural organic amendments such as compost into turfgrass disease management may be an alternative for dollar spot control Composting is the controlled rotting of organic matter The composting process is mediated by microbial activity and can be affected by physical and chemical characteristics such as temperature aeration moisture carbon to nitrogen ratio C N and pH The result is a stable end product with increased organic components and nutrient availability The process is considered to be the most efficient treatment in producing an envi Entomopathogenic Nematodes Control Annual Bluegrass Weevil How to Manage the Golf Course Pest 32 Continued on page 30 By J B Workman and C Waltz