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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94 GOLF COURSE MANAGEMENT 03.14 • Limited data are available on the effect of preven- tive versus curative fungicide applications, post- treatment irrigation and PGR use on the severity of brown ring patch. • Preventive fungicides that provided acceptable disease control included Affirm, Chipco Triton Flo, Heritage TL, Medallion and Prostar, as well as tank mixtures of Torque + Affirm and Velista + Heritage. • Curative fungicide treatments did not always provide acceptable control of brown ring patch. • Post-application irrigation appeared to improve curative disease control when Chipco Triton Flo (but not Heritage TL) was applied, and turf treated with Proxy + Primo had greater brown ring patch severity than the untreated control; however, additional research is needed to confirm these observations and to more fully un - derstand the impact of post-treatment irrigation and PGRs on this disease. RESEARCH SAYS a different quadrant of the green. The PGRs Primo MAXX (5 fuid ounces/acre [0.365 liter/hectare]), Proxy (217.8 fuid ounces/ acre [15.9 liters/acre]), Primo (5 fuid ounces/ acre) + Proxy (217.8 fuid ounces/acre), and Embark (22 fuid ounces/acre [1.6 liters/hect - are]) were evaluated for their effect on brown ring patch and seedheads, in comparison to an untreated control, at early spring applica - tion timings and rates typically used on golf courses throughout the Northeast. All treat - ments were applied on March 20 and April 5, 2012, and turf was maintained as described in our 2011 fungicide effcacy study above. This trial did not receive applications of any other PGR or fungicide treatments in spring 2012. All PGR treatments resulted in better turfgrass quality when compared to the un - treated control (data not shown). This was primarily due to increased seedhead forma - tion on untreated turf resulting in a whit- ish-brown color that lowered visual quality estimates. Embark, Proxy alone and Primo + Proxy treatments reduced seedheads com - pared to untreated and Primo-treated turf on the majority of rating dates in this study (data not shown). In the plots where seed - heads were suppressed, turf remained a dark green color, and ball roll would likely have been more uniform. Although all PGRs in this study except Proxy alone exhibited "numerically" more brown ring patch (greater disease severity) than untreated turf, only turf treated with Proxy + Primo had signifcantly more dis - ease than the untreated control on one rat- ing date (data not shown). These data sug- gest that PGR treatments that provide a high level of annual bluegrass seedhead and foliar growth suppression during spring may in - tensify brown ring patch disease on annual bluegrass putting greens. However, since this study was only conducted for one year, ad - ditional research is needed before this theory can be confrmed. Integrated management of brown ring patch Brown ring patch is a unique turfgrass disease that does not respond to management and environmental conditions in the same way as other diseases caused by R izoctonia. Historically, many R izoctonia diseases of cool-season turf have been associated with high levels of fertility and are not known to be affected by PGRs (3). Brown ring patch thrives under a wide range of temperatures that, in some regions, can be present from March through November. Our observation that turf in aerifcation holes was less affected by this disease confrms some previous re - ports suggesting that the amount of thatch, organic matter and compaction may play a role in disease severity and control (3). Superintendents should realize that main - taining greens under conditions of low nitro- gen fertility and aggressive PGR use (high rates and/or short application intervals) to en - hance playability may lead to enhanced dis- ease pressure and an increased reliance on fun- gicides to manage brown ring patch on annual bluegrass greens. Therefore, when environ - mental conditions favor disease development, less aggressive PGR use — as well as adequate irrigation, nitrogen fertility and fungicide ap - plications — should be used to reduce the po- tential for severe brown ring patch epidemics. If PGRs are being used to suppress seed - heads in early spring and the course has had a history of this disease, it would be prudent to make preventive applications of one of the fungicides found to be effective in this and other studies. Since fungicides are still strongly relied on for brown ring patch man- agement, selection of effective products is im- portant because many of the fungicides com- monly used on golf courses are not effective against this disease. Moreover, if brown ring patch becomes active, superintendents should not expect rapid symptom remission because research has shown that it typically takes 14-21 days or more for signifcant recovery to occur. Repeated fungicide applications on a 14-day interval and increased nitrogen ap - plications will aid in recovery if conditions re- main conducive for disease development. Acknowledgments We thank Fiddlers Elbow Country Club for the space and fexibility to conduct these trials on greens that remained in-play for the duration of the trials. We also thank Bayer, BASF, Cleary/Nufarm, DuPont, PBI-Gor - don, SePRO and Syngenta for providing product and support for these trials. Literature cited 1. Dernoeden, P.H. 2013. Creeping Bentgrass Manage- ment. 2nd ed. CRC Press, Boca Raton, Fla. 2. McDonald, S.J., D. Settle, L. Stowell et al. 2009. Chemical control of brown ring patch. Golf Course Management 77(8):82-88. 3. Smiley, R.W., P.H. Dernoeden and B.B. Clarke. 2005. Compendium of Turfgrass Diseases. 3rd ed. APS Press, St. Paul, Minn. 4. Toda, T., T. Mushika, T. Hayakawa et al. 2005. Brown ring patch: A new disease on bentgrass caused by Waitea circinata var. circinata. Plant Dis - ease 89:536-542. 5. Wong, F.P., C. Chen and L. Stowell. 2009. Effects of nitrogen and Primo MAXX on brown ring patch devel - opment. Golf Course Management 77(5):117-121. 6. Wong, F.P., and J.E. Kaminski. 2007 A new Rhizocto - nia disease of bluegrass putting greens. Golf Course Management 75(9):98-103. Steven McDonald (steve@turfgrassdiseasesolutions.com) is the founder of Turfgrass Disease Solutions LLC, Spring City, Pa., and an instructor in the Professional Golf Turf Program at Rutgers University. Richard Grala is a senior feld technician with Turfgrass Disease Solutions LLC. Bruce Clarke is the director of the Rutgers Center for Turf - grass Science and chairman of the department of plant biology and pathology and a 2014 recipient of GCSAA's Col. John Morley Distinguished Service Award. 078-095_March14_TechwellCuttingEdge.indd 94 2/18/14 1:46 PM

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