Golfdom, March 2014

FIGURE 1 Application rates and intervals Application interval days Number of applications 14 6 10 60 1160 632 14 6 20 120 2140 947 14 6 30 180 3120 1000 14 6 40 240 4100 1000 21 4 20 80 1427 684 21 4 30 120 2080 842 21 4 40 160 2734 947 28 3 40 120 2050 842 No spray 0 00 00 0 474 Adapted from Latin 2011 b Estimated retail cost of Chipco 26 GT applied to 3 acres of putting greens c Percentage of 19 evaluation days dollar spot severity was less than or equal to 05 accurate diagnosis of the problem you will succeed when applying fungicides Once an accurate diagnosis is accomplished and plant health has been addressed how do you select the right fungicide There are many sources that can aid in fungicide selection and I will list just a few of my favorites Dr Paul Vincelli from the University of Kentucky produces a document each year called Chemical Control of Turfgrass Diseases http www2 ca uky edu agc pubs ppa ppa1 ppa1 pdf that is an excellent resource for fungicide selection Dr Vincelli gathers data from all over the U S when compiling and updating this publication At N C State my predecessor Dr Lane Tredway developed an excellent disease management utility called NCSU Disease Management Utility http turfdiseasemanagement ncsu edu nc Right now we are working to update this FIGURING OUT FUNGICIDES Application rate oz M Total amount applied tool and we hope to have that complete by this summer Many turf scientists publish results of fungicide trials on their program website For example when I was at the University of Wisconsin Madison we published our fungicide trial work on our website www tdl wisc edu Here are just a few more websites that I have used in the past for management information these are by no means exclusive http plantscience psu edu research centers turf http turfpath missouri edu and http turf rutgers edu Dr Rick Latin at Purdue University published a book entitled A Practical Guide to Turfgrass Fungicides which is an excellent source for the basics of fungicides and for fungicide efficacy Finally if you are still uncertain about fungicide selection call your local turfgrass pathologist or turfgrass extension specialist The next step is picking the Total costb fung labor Benefitc application rate and volume and timing Fungicide timing can be tricky as there are many factors that govern timing of fungicide application However in order to maximize efficacy typically preventative applications are best Dr Latin showed this very well in his book He conducted a study examining application rates and intervals for dollar spot control using Chipco 26GT see Figure 1 He determined the benefit of each strategy he examined which was calculated as the percentage of 19 evaluation dates that dollar spot severity was less or equal to 05 percent He also included a total cost of the application strategy that included the fungicide cost and labor He found that applying the fungicide at two oz every 14 days provided 947 percent benefit at 2140 One hundred percent Continued on page 32 March 2014 Golfdom 31 Golfdom com