Golf Course Management

MAR 2014

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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03.14 GOLF COURSE MANAGEMENT 93 fungicide chemistries commonly available in the turfgrass market for both preventive and curative control of brown ring patch. These data confrm previous research showing that fungicides such as Affrm, Heritage, Medallion and ProStar, which are known to be effective against other R izoctonia diseases, also provide high levels of brown ring patch control (2). Briskway and Headway are pre-mixed fungi - cides that contain a DMI (difenoconazole and propiconazole, respectively) combined with azoxystrobin (the active ingredient in Heritage TL). Our data from 2013 indicate that these pre-mixes are as effective as Heritage for the control of this disease when applied curatively under moderate disease pressure. Post-application irrigation and efficacy of curative fungicide treatments, 2011 Two of the most effective fungicides in our 2011 trial, representing two different chemical classes, were selected to evaluate the effect of post-treatment irrigation on cu - rative control of brown ring patch. Heritage TL (2 fuid ounces/1,000 square feet [0.64 milliliter/square meter]) and Chipco Tri - ton Flo (0.75 fuid ounce/1,000 square feet [0.24 milliliter/square meter]) were applied once curatively on April 25. The study was arranged as a split-plot design (each plot had an irrigated and non-irrigated half ) with four replications. Water (0.15 inch [3.81 mil - limeters]) was supplied to the irrigated half of each plot immediately following fungicide application (within 5 minutes) using a water - ing can. Post-application irrigation improved brown ring patch control on turf treated with Chipco Triton Flo, but not Heritage TL (data not shown). Although these results are infor - mative and suggest that post-treatment irriga- tion may improve brown ring patch control for some fungicide chemistries, additional re - search is needed before defnitive statements can be made since only two products were evaluated for one year in this small pilot study. Additional field observations Where brown ring patch was severe in our trials, a signifcant degradation of thatch occurred (visual observations), especially in untreated plots. Following the completion of our trials, we also saw a greening response in areas that had been severely blighted. This has previously been reported (6) and is shown in the photo. This symptom is likely due to a breakdown of organic matter (thatch) and a release of nitrogen and other nutrients re - sulting in enhanced greening that could be confused with Type II fairy rings (dark green stimulated turf in a circular patch). Fungi - cide applications targeting these fairy ring- like symptoms would likely have no effect if the patches were caused by brown ring patch. Another interesting feld observation was that annual bluegrass growing in the aerifcation holes from the previous autumn was seem - ingly unaffected by brown ring patch. This could possibly be due to deeper rooting in the aerifcation holes resulting in improved plant health or because fertilizer had collected in these areas and enhanced turf vigor. It is ap - parent from this observation that further re- search is needed to determine the impact of aerifcation and rooting on brown ring patch. Effect of spring applications of PGRs on disease severity, 2012 This small trial was conducted on the same putting green at Fiddlers Elbow Country Club as our 2010 and 2011 fungicide trials, but in All PGR treatments resulted in better turfgrass quality when compared to the untreated control (data not shown). In the plots where seedheads were suppressed, turf remained a dark green color, and ball roll would likely have been more uniform. 078-095_March14_TechwellCuttingEdge.indd 93 2/18/14 1:46 PM

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