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Turf Rx

By |  July 5, 2017 0 Comments
The shrinking of sprayer technology and the introduction of GPS mapping systems has allowed superintendents to become even more precise with their applications. The Oglebay Resort, Wheeling, W.Va., (pictured) utlizes the technolgy on its four courses.

The shrinking of sprayer technology and the introduction of GPS mapping systems has allowed superintendents to become even more precise with their applications. The Oglebay Resort, Wheeling, W.Va., (pictured) utilizes the technology on its four courses.

In prescription turf management, you’re the pharmacist.

Many tools of our trade have their roots in agriculture. Things like drainage, seeders, fertilizer spreaders and sprayer technology have been influenced by the agricultural industry. Most of these tools started off as rough approximations of what we recognize today.

The demand for more refined outcomes with much tighter tolerances has driven the improvement of these tools, giving us a host of new products. There’s no clearer example of this in the past five years than the shrinking of sprayer technology, namely the introduction of GPS mapping systems. While accuracy to a within a few feet may be sufficient for fields covering hundreds of acres, spraying just 25 acres of fairways, let alone 3 acres of tees, necessitates higher accuracy. Equipment is now accurate to inches rather than feet and continues to improve.

In the past few years, many of us have jumped on the bandwagon of these new sprayer systems, helping us refine the boundaries of application areas, eliminate tracking dye or foam, improve application under/overlap and decrease excess application area because of whole boom versus individual nozzle control. It’s been about improving efficiency, but that’s not the whole story. These systems offer opportunities to take progress even further.

Consistency’s the goal, but how?

Enter prescription turf management, something that most of us do already in some form or fashion. Examples include adjusting sprinkler run times to accommodate a wet or dry tee box, reducing the amount of fertilizer applied to part of a fairway and using soil moisture probes and their data to irrigate and create a more homogenous putting green.

Consistency is the goal, but with so many variables, consistency sometimes seems unattainable. So, what does it take to improve uniformity further than we already have? The answer, at least to start, is data. How healthy is our turf? We need to know how turf is performing so we can make necessary adjustments to programming. We also need to catalog the location of this data. Where exactly is the turf in need of more inputs or fewer inputs?

Widespread availability of affordable data has improved dramatically in recent years. Superintendents can obtain Normalized Difference Vegetative Index (NDVI) data from satellites, plane flyovers, or with the most recent method, drones. In general terms, NDVI is a measurement of the photosynthetic abilities of vegetation. Plants that are healthy and productive easily can be differentiated from those not growing as vigorously. Once we have this data we can make further inferences about the causes of problems and best ways to adjust our management practices.

At Wayzata Country Club, we now use NDVI data in combination with our sprayer control systems to adjust our fairway fungicide program. By extracting the plant health information from NDVI data, we look at how and where we could reduce our total inputs. Seeing what the NDVI imagery shows as higher performing turf versus poorer performing turf is no surprise. The areas with better performing turf are all locations that rarely require extra care, and the lesser performing areas are those needing extra attention in the past.

It’s also interesting to identify problem causes for some of the lesser performing areas. For example, many areas of WCC that show up lower on the NDVI scale can be attributed to high traffic and fairway expansions. The reasons stressed turf shows up lower on the NDVI scale are numerous, and it takes the knowledge and experience of the superintendent to determine the root cause of this stress. It’s also telling that the areas where dollar spot first appears are almost always areas that are lower on the NDVI scale.

Mapping fungicide need

With this information in hand, we next determine how to alter a fungicide application for its best use. With some apprehension about venturing into the unknown, I started our program with just two application rates, 1 gallon per thousand GPK and 1.5 GPK. From there I generated a prescription map, delineated into two parts, with lesser performing turf on the NDVI scale receiving the 1.5 GPK and the better performing and less stressed turf receiving 1 GPK. Essentially, I apply only 2/3 of a tank mix in areas that the satellite and I agree could do with less. The determination of that line is completely subjective, it could be set anywhere along the NDVI scale. My initial goal was to reduce total fungicide use by 15 percent to 20 percent, which helped determine the separation line between rates.

Trcka uses NDVI data in combination with sprayer control systems to adjust his fairway fungicide program at Wayzata CC. By extracting the plant health information from NDVI data, he looks at how and where they could reduce their total inputs.

Trcka uses NDVI data in combination with sprayer control systems to adjust his fairway fungicide program at Wayzata CC. By extracting the plant health information from NDVI data, he looks at how and where they could reduce their total inputs.

With map in hand — or more precisely, loaded into the sprayer computer — it was time to make an application. One big question quickly was answered — the sprayer transitioned smoothly from rate to rate on the same fairway, so it was a success from a technology standpoint.

The turf health standpoint was the next question. Would the 2/3 rate application be effective for as long as the full rate? Our observations indicated a resounding yes. There was no observable disease incidence at the lower application rate, even at intervals recommended for the higher application rate. For example, a 3-oz./1,000 rate will last at least 28 days, and a 2-oz. rate will last 14 to 21 days. Our prescription map allowed us to apply 3 oz./1,000 to areas of higher disease pressure and a 2 oz./1,000 rate to areas of lower pressure as well as maintain a minimum interval of at least 28 days.

With the ability to apply 2/3 of a tank mix in specific areas of the course, Jesse Trcka was able to decrease his fungicide use by up to 20 percent.

With the ability to apply 2/3 of a tank mix in specific areas of the course, Jesse Trcka was able to decrease his fungicide use by up to 20 percent.

Seeing it firsthand changed my perspective on both the rates of fungicides and frequency of applications. Rather than maintaining a two- to three-week preventative application schedule, I am now more comfortable stretching the intervals to four-plus weeks. With the change in frequency, I’m also adjusting rates accordingly, knowing that a higher label-rate application won’t be applied evenly across the whole golf course, only in areas that it has been designated necessary. The net result is fewer applications, fewer inputs and overall cost savings.

We will expand the parameters that we have set in our use of the system, for example, adding one or two more application volumes to the prescription maps for further reductions. This means adding an intermediate rate of 1.25 GPK, and even a 0 GPK for areas that have minimal disease incidence and low pressure. We’ll also look at adding fertility and wetting agents into the equation in our continued effort to create a more homogenous turf stand.

The downside

Now for the downside. Some products are not as conducive to variable rate applications, at least not in the same tank mixes I have referenced. More actively functioning — and probably growing — areas of turf requiring lower fungicide rates probably are not the areas we want to target for a lower rate of a PGR. Unfortunately, this means additional applications of PGRs and any other product, like a phosphite, that don’t fit the same prescription map. This doesn’t mean we can’t create maps to target areas where a higher PGR rate would be beneficial, but it wouldn’t be the same map.

At Wayzata CC, Trcka makes applications ranging from 3 GPK to 0 GPK depening on the turf in the area’s disease incidence frequency and pressure.

At Wayzata CC, Trcka makes applications ranging from 3 GPK to 0 GPK depending on the turf in the area’s disease incidence frequency and pressure.

Making these extra apps may be a dealbreaker for many, but with only PGRs going into the tank, these applications go quicker than we thought. Along the same lines of reducing total number of fungicide applications, there is a consideration to make in adjusting PGR rates and reducing the frequency of these applications as well.

I’ve asked myself if we have met our reduction goals, and if so, was it worth the additional effort? The answer is yes to both questions. Not only did I start the season not intending to make as many variable-rate applications as we did, but I had planned to do the opposite. But as the year moved on, the savings were as obvious as the extra product on the shelf. It goes without saying that many of these fungicides are costly, and savings add up quickly. I speak for myself when I say that the cost savings, along with reduction in inputs, more than make up for the additional labor costs and time lost from other areas.

I would be remiss to not reference the others involved in this process. When I reference “we,” I refer to Aaron Johnson of Winfield and Ken Rost and Kirk Stueve of Frost Inc. Without their assistance, none of this would have come about. Utilizing their knowledge to access the necessary NDVI data from GeoTech and turn that into specific prescription maps was essential. It was an interesting and rewarding process that has left us looking forward to how we can continue to grow in our use of this technology.


Jesse Trcka is superintendent at Wayzata Country Club in Wayzata, Minn. This article originally appeared in Hole Notes, official publication of the Minnesota GCSA, and is reprinted with permission.

Photos: Jesse Trcka, (sprayer photos) Grant Gannon

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