Golfdom, March 2014

I think the benefit of most biological treatments for dollar spot control remains questionable However most research with mineral oil applications shows a reduction in dollar spot severity compared to untreated turf and suggests that control with conventional fungicides can be improved by including the mineral oil in a tank mix Some turf scientists have rediscovered the fungistatic nature of two plant growth regulators PGR flurprimidol Cutless and paclobutrazol Trimmit These compounds are related to DMI fungicides and will reduce disease severity However because of their chemical similarity to DMI compounds they are likely to accelerate the rate at which pathogen populations evolve towards resistance to registered DMI fungicides Fungicide resistance within dollar spot pathogen populations should be a consideration in any program that involves these two PGR compounds Because of the season long dollar spot threat most effective approaches involve repeated application of fungicides at regular intervals Higher rates and shorter intervals will result in a reduced risk of serious dollar spot outbreaks One of the more contemporary issues with regard to dollar spot control involves the timing of the initial application There is the notion that early first or second mowing applications of a certain fungicide will limit dollar spot development for months afterward Any explanation must be based on logic and the biology of the dollar spot pathogen rather than unsupported supposition Given the nature of apical growth in fungi the pathogen must be active growing for the fungicide to be effective If environmental conditions favor pathogen growth and an effective compound is applied at that time the fungus will acquire the fungicide Once inside the mycelial threads the fungicide disturbs cellular functions stopping pathogen growth allows turf to recover and effectively controls the potential outbreak For any geographic location historical temperature averages define the dollar spot window In most cases the initial fungicide application scheduled at the beginning of the window is most effective So here we are at the beginning of the 2014 season poised to do battle with this simple but stubborn pathogen Our approach must be based on a sound disease control strategy that includes reducing disease pressure through implementation of sound cultural practices understanding efficacy and limitation of fungicides registered for use against dollar spot anticipating the initial outbreak and following a preventative rather than curative approach and positioning your dollar spot sprays with consideration of other diseases that threaten as the season progresses Rick Latin Ph D is a professor in the Department of Plant Pathology at Purdue University specializing in turfgrass disease identification and control Dr Latin can be reached at rlatin@ purdue edu for more information SEEING SPOTS Ad Index Companies featured in this issue ADVERTISER PAGE AMVAC 37 Bayer 15 33 Control Solutions 3 Ecolawn 36 e par 35 FMC Corp 13 GenNext CV4 Helena Chemical Co 17 Hunter Industries 23 J2 Golf Marketing 22 ADVERTISER PAGE Jacobsen 7 John Deere CV2 1 Kochek Co Inc 41 Nufarm 20 PBI Gordon 4 41 Pearl Valley Organix 5 Smithco 11 Soil Technologies 29 Syngenta CV3 Turfco 21 Denotes regional run This index is provided as an additional service The publisher does not assume any liability for errors or omissions Boosts Turf and Cuts Costs TurfTech Bio Min has reduced the need for granular fertilizers on my 40 acres of bentgrass turf which saves my golf course money Bio Min helps me to actually grow grass in the summer instead of always just fighting to keep it alive Richard Hynson Supt Boone Valley Golf Club Augusta MO Supplies Four Tools in One Product t Soil Conditioning Polysaccharides t Biofungicides to Suppress Pathogens t Nitrogen Fixing Microbes Beneficials t Volcanic Minerals 60 Elements www soiltechcorp com 1 800 221 7645 x105 March 2014 Golfdom 29 Golfdom com