GOLF COURSES FIND VALUE IN COMPOST TEA PROGRAMS

BioCycle October 2003, Vol. 44, No. 10, p. 22

San Francisco turf (and golfers) benefit from applications of compost tea that minimize need for toxic chemicals.

Karin Grobe

PEST management on golf courses has traditionally included regular pesticide applications, particularly on greens. But many courses are under increasing pressure to minimize the use of chemicals, and managers are looking for alternatives. Based on recent trials in San Francisco, compost tea is emerging as an effective tool for suppression of turf diseases as well as overall reduction of synthetic fertilizers.
Phil Rossi, Integrated Pest Management (IPM) Coordinator for Golden Gate Park in San Francisco, has been using compost tea for control of fungus diseases since 1997. Tea is used as a soil drench and as a foliar on golf and lawn bowling greens. “Fungus is the number one problem for greens, and we used to apply fungicide on a regular schedule,” he says. Greens are under stress due to compaction caused by foot traffic, close-crop mowing and San Francisco's foggy weather. “Ammonium fertilizers also deplete the microorganisms that could help to crowd out agents that contribute to fungus,” says Rossi.
Tea is also used in the Conservatory of Flowers, where it “creates a biofilm on leaf tissue,” says Rossi. “Essentially, that's a screen or shield of plant health-promoting microorganisms. They colonize the leaf surface and create a barrier against pathogenic organisms.” Rossi explains that compost tea is not the end-all step for turf and plant health; rather it's the last layer of a whole-system biotic approach.”
Tea is brewed in two 100-gallon and one 25-gallon brewers purchased from Growing Solutions (www.growingsolutions.com). Compost is a 50-50 blend of vermicompost from a worm farm in Florida and thermophilic compost made by the San Francisco Presidio Trust. Tea is diluted with an equal volume of dechlorinated water and applied at a rate of two gallons per 1000 square feet every two weeks. “Since you have to brew the tea, it's a little more labor than fungicide applications,” says Rossi, “But in terms of the application, it's a wash.” Boom-type power sprayers are used to apply tea to the greens and gun applicators are used in the Conservatory.
San Francisco's overall IPM policy was implemented in 1997 by city ordinance. City parks staff must employ nonpesticide management tactics first and use chemicals only as a last resort. The program has improved safety for golfers and lawn bowlers as well as city workers. “From our standpoint, it's definitely a worthwhile program,” says Rossi.

PROGRAMS AT THE PRESIDIO
Christa Conforti, IPM Coordinator for the Presidio Trust in San Francisco, evaluated the effects of compost tea on golf course greens over a one-year period. Greens were sprayed with one gallon of compost tea per thousand square feet weekly during times of high disease pressure and every two weeks during times of moderate or low disease pressure. Application methods alternated between drench applications in which the tea was watered in for 5-10 minutes after being applied, and foliar applications in which the tea was left on the surface of the greens.
Turf treated with compost tea had less microdochium patch disease, a foliar fungus, than untreated turf. Thresholds for disease on golf greens are very low. Mean percent of turf area with microdochium symptoms was 0.042 percent for compost tea-treated plots. In contrast, 0.604 percent of untreated turf exhibited symptoms.
Turf treated with compost tea had longer root length than untreated turf. Mean root depths of treated turf was 2.5 inches, while that of untreated turf was 1.9 inches. A deeper root system improves the ability of turf to withstand foot traffic.
Compost and compost teas are made on-site. Compost is made from equal parts wood chips, grass clippings, horse manure and horse bedding. Biodynamic preparations are added to the windrows and compost is processed for a minimum of four months. Growing Solutions tea brewers are used and additives (molasses, sea kelp, cane sugar, rock dust, yeast) are added before brewing. Tea is applied with a boom sprayer within four hours of brewing.
Conforti has made compost tea an integral part of the Presidio Golf Course turf maintenance program. “The differences in rooting depth and microdochium patch were small, but they were significant,” she says.

Karin Grobe is editor of “From The Ground Up,” a newsletter funded by the San Jose, California Environmental Services Department. Visit www.urbancompost.org.

PREDICTING QUALITY OF COMPOST TEA RECIPES
IN a BioCycle report on evaluating anticipated benefits from applying compost tea, Vicki Bess - director of BBC Laboratories in Tempe, Arizona - emphasized using only the highest quality compost that is “rich in microbial numbers and diversity.” Some types of microorganisms like to live attached to particulate matter, and a compost tea made using a fine mesh strainer (popular for tea destined for drip irrigation) doesn't let a sufficient amount of particulate matter through to support these microorganisms. “Beneficial fungi and actinomycetes prominent in a good compost may be poorly represented in the compost tea simply because of the need to strain out material,” Bess pointed out. “Keep in mind that compost tea microbiology is most impacted by oxygen availability, nutrient availability and initial microbiology of the compost used to make the tea.”
Compost teas are applied either to the soil or to the plant foliage. Those applied to the soil will move into the root zone and affect the plant's rhizosphere. Nutrients will be used by the plant as well as soil microorganisms. The method works in greenhouses, fields and orchards - as well as on golf courses.

INTEGRAL PART OF TURF MANAGEMENT
COMPOST TEA has become an integral part of the pest management and general turf management program on all Presidio Golf Course greens.” That was the conclusion of a research paper presented in 2002 at the International Symposium on Composting and Compost Utilization sponsored by BioCycle and The Ohio State University. The paper was written by Christa Conforti, Marney Blair and Jean Koch of the Presidio Trust; and Kevin Hutchins of the Arnold Palmer Golf Management Company in San Francisco.
A new growing trial with bunchgrass that involves applications of compost tea as well as compost is underway at the Presidio, Christa Conforti notes. Crissy Field is a former U.S. Army air field which is now part of the Presidio National Park. In 2000, the concrete airfield was removed and much of the field was planted with Deschampsia, a native bunchgrass. As part of an ongoing effort to better maintain it, the Presidio Trust and the National Park Service are in the midst of a year-long trial to compare the effects of compost, compost tea, organic fertilizers, and chemicals fertilizer on the Deschampsia and on the soil at Crissy Field. Treatments include monthly applications of two gallons per 100 square feet of compost tea, quarterly applications of one-quarter inch of compost, compost plus compost tea, monthly application of an organic fertilizer, and quarterly applications of a synthetic fertilizer; a biodynamic treatment is also being tried. Turf color, turf density, root depth, thatch depth, disease incidence, and soil microbiology are being monitored.

Copyright 2003, The JG Press, Inc.