Golfdom, March 2014

FIGURE 2 Mycelium is produced within infection centers after long periods of surface moisture triadimefon triticonazole difenoconazole and dicarboximides iprodione vinclozolin The contact fungicide chlorothalonil remains an important part of any program because of its broad spectrum of activity It is effective against many diseases including dollar spot and its multi site nature The multi site feature is essential in anti resistance strategies because the likelihood of a pathogen population evolving a resistance to a multi site compound is zero or near zero It kills fungal cells without the risk of selecting for resistant individuals However there are governmentimposed limits to the amount of chlorothalonil we can apply and these restrictions complicate the task of controlling disease on fairways Successful superintendents rely on their understanding of fungicide strengths and deficiencies to schedule chlorothalonil sprays at the most opportune times to get the most out of each application The new fungicide f luazinam Secure Syngenta will be especially helpful where fairway outbreaks are a serious concern Fluazinam is actually an old fungicide that was only recently introduced to the turf market It is also a contact material and is advertised as a multi site compound Fluazinams forte is in dollar spot control and it should be used judiciously to relieve some of the burden from chlorothalonil In reality it is not multi site to the same degree as chlorothalonil Fluazinam has a FRAC code of 29 as opposed to chlorothalonils FRAC code of M There is suspected resistance to a Botrytis related to Sclerotinia pathogen of crops in Japan The point in making the distinction is that we should be careful not to over use fluazinam and tempt fate with the evolution of fungicide resistance Other fungicides for dollar spot SEEING SPOTS control are classified as penetrants Active ingredients diffuse into leaves and stop or limit pathogen growth inside turf plants thats the main reason why they tend to keep dollar spot outbreaks at bay for longer periods of time than contact fungicides Among the most widely recognized penetrants are the DMI compounds the dicarboximides and thiophanatemethyl They can be effective against many different turf pathogens but are site specific fungicides like all penetrants meaning that populations may evolve to the point where the majority of individuals become resistant to the active ingredient This results in failure to control The newest active ingredients introduced into turf markets are in a class called SDHI Succinate DeHydrogenase Inhibitors It is likely that this class will be subdivided since active ingredients do Continued on page 28 March 2014 Golfdom 27 Golfdom com