Built on the former site of the Cheetham Salt Works, an industrial mining plant outside Melbourne, Australia, the Sanctuary Lakes Golf Course is a link-style course that has been praised by golfers and environmentalists. The course abuts a breeding habitat for rare migratory birds, and the adjoining wetland is protected under international covenants. The Sanctuary Lakes Resort, of which the golf course is a part, won the 2004 GreenSmart Award and Australia’s National Environmental Excellence Award.
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The course, which was designed by Gregg Norman and opened for play in 1999, has undulating fairways accented with dramatic bunkering and wild roughs. Peter Jans, course and estate operations manager, has been working at the course since its inception. Drawn to Sanctuary Lakes by its environmentally friendly stance, Jans relied on chemical fungicides as the backbone of his disease management program for several years. Six years ago, Jans made the switch to an organic, biologically based fertilizer and disease control regimen.
A two-pronged approach
Jans took a two-pronged approach to making Sanctuary Lakes’ greens and fairways as disease-free as possible. His first step was to change his fertilizer regimen to address salt-related issues. He switched from a traditional granular fertilizer to a low-salt liquid fertilizer, and enhanced the fertilizer program by adding a calcium-rich liquid product and a product high in humic and L-amino acids.
Jans was pleased with the ease with which the liquid products could be applied through a boom and appreciated the fact that foliar feeding reduced nutrient loss from volatilization and leaching. He also appreciated how the organic products revitalized the course’s soil, which was naturally high in salt.
High salt levels can damage a soil’s structure, leading to soil compaction and reduced water and oxygen penetration. Unless proactively managed, salt accumulates in the soil and can cause water to move out of, instead of into, turf root cells, lead to burning and stunted growth.
In high sodium soils, individual soil particles repel each other, resulting in poor soil structure. When calcium is added, the sodium in the soil is replaced, causing soil particles to flocculate or aggregate together. This creates a more porous soil and allows the sodium to naturally leach out of the root zone with rainfall and irrigation. The addition of calcium improves soil condition by improving the soil’s cation exchange capacity and by increasing the activity of beneficial soil organisms.
Granulated lime and gypsum are commonly used sources of calcium, but Jans chose a chelated calcium product in a liquid formulation. The product he uses is a 100-percent soluble calcium and nitrogen complex that can be tank-mixed with other products and allows for immediate uptake through leaves and root tissue.
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Salts in soils also can be neutralized by organic carbons such as humic acid and natural L-amino acids. These acids are large and complex carbon molecules that absorb sodium ions.
The second prong: biological fungicides
The second part of Jans’ two-prong approach to disease management was to move away from using mostly synthetic broad-spectrum fungicides to using mostly bacteria-based biological fungicides. Since making the move, Sanctuary Lakes’ fungicide expense declined from $20,000 for the 1999-2000 fiscal year to an average of $2,500 for each fiscal year since then.
The Sanctuary Lakes course has Providence (SR 1019) bentgrass greens and Santa Ana Couch fairways, surrounds and tees. Before the new fertilizer and fungicide program, the course experienced recurring problems with fusarium, rhizoctonia, pythium and rairy ring. The fusarium, rhizoctonia and pythium problems have disappeared almost, and fairy ring as become an occasional, rather than a near-constant, problem.
The biological fungicide Jans uses is based on a patented strain of Bacillus subtilis, which is a naturally-occurring, beneficial microorganism found in everything from pine needles in Australia to estuaries in the southern United States.
Bacteria-based biofungicides work in several ways. When applied to the soil or to a foliar surface, the beneficial bacilli crowd out the disease-causing microbes. The beneficial bacilli in the biofungicides also attack and kill pathogens, usually by puncturing the pathogens’ cell walls or by producing antibiotics that disable the pathogens. Because of these multiple modes of action and the nature of the bacillus, there's much reduced risk pathogens will develop a resistance to the biofungicides.
In addition to crowding out and attacking pathogens, biological fungicides produce biostimulants and auxin-like substances that increase plant health and make turf more able to withstand stress.
Biological fungicides also can be used effectively in combination with traditional fungicides. At Sanctuary Lakes, Jans has tank-mixed the biological fungicide with reduced rates of a syntheic fungicide to ward off stubborn recurrences of fairy ring.
Other turf managers have noted the synergy achieved when biological and traditional fungicides are combined. Golf course managers who tank-mix a biofungicide and a chemical fungicide often attain levels of disease control that equal or exceed those attained when the chemical fungicide is used at full-strength. At the same time, managers reap the benefits of reduced chemical costs.
