Kerry Satterwhite, CGCS, says superintendents have a responsibility to manage facilities with less-conventional pesticides. He has designed a biological testing program that has allowed him to eliminate conventional fungicide applications on 10 acres of bentgrass greens on two courses.

2000 Leo Fester Award candidate

In his efforts to reduce the use of conventional pesticides, Kerry Satterwhite, CGCS, developed a program using biological alternatives to eliminate fungicide applications on 10 acres of bentgrass greens on two courses. A variety of products were used, with marginal success when used individually but with a better results when some were combined for a synergistic effect. The 10 acres of Crenshaw tees had to be removed from the biological trial last year because of difficulties controlling dollar spot. Despite efforts to hold off on conventional pesticides, after an extended heat wave with high humidity, it became necessary to apply fungicide to the greens. The superintendent will evaluate the application schedule and materials further before continuing the biological trials next season.

The biostimulant market in the turfgrass management industry has increased exponentially over the past five years. There is no shortage of products that claim to "stimulate phenomenal root growth" or "increase beneficial microbial activity."

How do you sort out the good from the bad? What works? What doesn't? Which products are cost-effective and efficient? I have spent the past four or five years evaluating a number of these materials, and my failures with them have far outnumbered the successes.

I believe we have a responsibility to try to manage our facilities without using as many conventional pesticides as we have in the past. In my efforts to accomplish that, I have put together a program that has allowed me to eliminate conventional fungicide applications on 10 acres of bentgrass greens on two of the courses I manage. Although most of this evidence is anecdotal, there are some supporting university research data (1998 Field Evaluation of Microbial Inoculants, Eric B. Nelson, department of plant pathology at Cornell University in Ithaca, N.Y.).

Materials and application
There was no established protocol for the independent trials, and all the products I've used over the past few years were purchased in full. I have no allegiance to any of the companies that manufacture these materials nor any special relationships with the distributors from whom I make my purchases.

The original goal of the program was to reduce the number of fungicide applications made to greens and tees from years past.

Some marginal success was achieved with each of these products individually but not to the extent that fungicide applications could be significantly reduced or eliminated. However, this season several of the materials were combined under the hypothesis that a synergistic effect could be created. At this point, that effect seems to have occurred. The control plots and areas not treated displayed severe disease activity.

The program was initiated on two courses. The first, Prairie Vista, opened for play in 1991 and has predominantly Penncross bentgrass on the greens and tees. The second, The Den, is a new Arnold Palmer signature course that opened last July. The greens are Providence on a straight sand root zone, and the tees are a blend of Crenshaw, Southshore and Penneagle on native soil. (Dollar spot has been a severe problem on the Crenshaw.)

Several materials are used in our program; a couple of them are rotated in and out of our cycle. They are listed below with application rates and frequency of application.

	Bac-Pack: 1 pint per acre beginning April 15, at 7-10 day intervals until the first frost; 2 pints per acre June 30-Aug. 30
	Turfshield (formerly BioTrek 22G): 1.5 pounds per 1,000 square feet applied March 27
	CytoFe: 1 gallon per acre (tank-mixed with Bac-Pack) applied once a month
	Macrosorb Foliar: 2 ounces per 1,000 square feet applied about every 14 days -- every other Bac-Pack application
	MicroGro: 1 pound per acre applied once a month
	HHI 15-4-7 greens grade fertilizer: 4 pounds of N per 1,000 square feet at six-week intervals (new greens); 2.5 pounds of N per 1,000 square feet per growing season (old greens)

The original plan was to reduce the number of fungicide applications made to greens and tees from years past. We were able to wait until late July before greens needed to be treated with a conventional fungicide. The 10 acres of tees were included in initial applications, but it became necessary to make routine fungicide applications to the tees. One of the factors contributing to this was the amount of dollar spot in the Crenshaw. Experience has taught us that this is not the ideal bentgrass for the climatic conditions typical of central Illinois.

Once it became obvious that the tees were not going to hold up, we dropped them from the trial and focused on the greens. One of the concerns was the effect of fungicide applications on the microbial population, which is perhaps a factor that we should evaluate next season by more closely examining biomass in the profile.

It is recommended that some of these biorationals be applied in the evening to avoid photodecomposition from UV rays. Last season, our applications were made in the evening, but this year, all our applications have been pre-dawn and lightly syringed in. We have seen better results this season and hope our efficacy continues to increase next season.

Control challenges
We do not generally use plant growth regulators (PGRs) as part of our maintenance regime. However, during early July we had several events and local tournaments, including a site visit by Palmer for a round of golf.

Satterwhite says both of the courses in the program are fairly rural and immature, and air movement and greens drainage is more than adequate. There are times when mowings are skipped, heights of cut are bumped up and the fairways are mowed less frequently than ususal — all elements that contribute to the overall health and vigor of the turf.

Our usual maintenance routine is to topdress very lightly every Monday; double cut Tuesday, Thursday and Saturday; and cut and roll Wednesday, Friday and Sunday, with an occasional afternoon cut to further increase green speed. We are a public course with undulating greens so our goal is to have them roll consistently at about 10. We believed it was necessary to try to get our greens to tournament speed, so we made an application of a PGR at 0.10 of an ounce per 1,000 square feet.

About four days later, we had brown patch symptoms. The disease was not severe; it was what has become familiarly known in this part of the country as "subliminal brown patch." Environmental conditions changed shortly after the symptoms appeared, and the greens remained healthy and growth was vigorous.

Satterwhite empasizes that his type of program may not work for every superintendent. He says the program fits well with the courses' other IPM and cultural practices

However, during July we were subjected to 15 days of daytime highs near 95 degrees and overnight lows above 70 degrees, accompanied by high humidity. This type of weather used to be unusual, but unfortunately it's becoming more typical in this area.

On July 26, the greens at The Den were treated with Spotrete Thiram to control brown patch that had finally exceeded acceptable threshold levels. This application was made toward the end of the extended heat wave. On the same day, the greens at Prairie Vista were treated with a combination of Heritage and a chlorothalonil product to control brown patch, anthracnose and some dollar spot that had started to appear. To date, these are the only fungicide applications that these greens have received.

The ideal interval rate seems to be in the seven- to 10-day range. On two occasions at Prairie Vista we allowed 13 days between applications, and each time we began to see a little dollar spot on the perimeters of the green or on the fringe, which we believed may have been a coverage problem. It also appears necessary to include some type of nitrogen source with the biological. It may be doing nothing more than assisting the plant to grow out of the symptoms, but when a nitrogen source was not included, the material was less effective.

Conclusions
Currently, it's unrealistic to expect to sustain quality turfgrass without the use of conventional pesticides. I would like to be able to write that we've completely eliminated them from our management program, but that has not yet occurred.

Satterwhite had marginal success using the products individually but not to the extent that fungicide application could be significantly reduced or eliminated. Last year he combined several materials to achieve a synergistic effect.

As the season winds down, we will evaluate our application schedule and materials used, and make the changes we believe necessary to continue our quest to eliminate conventional fungicides. One of the goals for next season is to determine why the program was ineffective on the tees. The difference in cultivars was one contributing factor, but the Penncross greens were almost disease-free for the entire season, whereas dollar spot continued to be a problem on the Penncross tees. This will be the greatest area of focus for next season's program.

This type of program may not work for everyone. Both of these courses are fairly rural and immature, and air movement and greens drainage is more than adequate. The program fits well with our other IPM and cultural practices -- factors that will certainly vary at each golf course. Even though we are at upscale public facilities, green speed is not a major concern. There are times we skip mowings, bump up heights of cut and back off on the frequency of mowings, all elements that contribute to the overall health and vigor of the turf. These practices may be unacceptable at many facilities.

Kerry Satterwhite, CGCS, is director of golf course maintenance for the city of Bloomington, Ill., and a 16-year GCSAA member. This article was published in the October issue of On Course, the publication of the Midwest Association of Golf Course Superintendents.