Research on a new combination material shows promise against two important diseases of creeping bentgrass: dollar spot and brown patch.

Tartan combines two active ingredients (triadimefon and trifloxystrobin) to provide effective control of many important turfgrass diseases. The triadimefon component (manufactured separately as Bayleton) is effective against foliar diseases, such as dollar spot and brown patch, and can be used to suppress damage caused by root diseases, such as summer patch and take all patch. The trifloxystrobin component (manufactured separately as Compass) provides excellent brown patch control and is effective against anthracnose and gray leaf spot.

Clusters of small, circular patches with bleached leaf blades are characteristic dollar spot symptoms.

Dollar spot is one of the most common and readily identifiable diseases on golf course turf. It is caused by a fungal pathogen (Sclerotinia homoeocarpa) that blights leaf tissues but does not affect turfgrass roots or crowns. The disease is a major concern on golf course turf, especially creeping bentgrass and annual bluegrass greens, tees and fairways, where it can affect playability as well as appearance. Characteristic symptoms on creeping bentgrass greens include small (up to 1 inch in diameter), round white- to tan-colored spots (Fig. 1). The spots often occur in clusters and can cause considerable damage to playing surfaces if not appropriately managed.

Brown patch is caused by a fungal pathogen (Rhizoctonia solani) that affects all cool-season turfgrass species. Moderate to severe outbreaks on high-maintenance creeping bentgrass and annual bluegrass can result in thin, poor quality turf that may be predisposed to algae and moss infestation. Even mild brown patch outbreaks can spoil the appearance of golf greens and tees. Taller mowed turfgrasses for athletic fields and professional landscapes (especially tall fescue and perennial ryegrass) also may sustain damage from brown patch infection. Under favorable environmental conditions (e.g. hot, humid weather) brown patch symptoms may develop overnight.

Brown patch symptoms include circular olive green patches surrounded by a band of water-soaked leaf blades with visible mycelium.

On creeping bentgrass and annual bluegrass greens, tees and fairways, brown patch results in circular olive green stains, ranging from 4 inches to more than 12 inches in diameter. Similarly, large, round patches of blighted turf can also occur on perennial ryegrass collars and fairways. Leaf blades within the patch become water-soaked and turn brown soon after infection. After warm and humid evenings, a dark gray to light gray band (quarter-inch to one inch wide) is normally evident at the perimeter of active patches (Fig. 2). The band (often called a smoke ring) is a sign of the advancing fungal mycelium and water-soaked infected leaves.

Trials in 2005

The dollar spot trial was conducted at the Daniel Turfgrass Research and Diagnostic Center on the campus of Purdue University in West Lafayette, Ind. Efficacy of Tartan for dollar spot control was evaluated on creeping bentgrass (cultivar L-93) maintained at a fairway mowing height of approximately one-half inch.

Plots were sprayed with Tartan, manufactured by Bayer Environmental Science, at rates equivalent to 1.0 fluid ounces per 1,000 square feet and 2.0 fluid ounces per 1,000 square feet at 21-day intervals beginning on May 25, when no disease symptoms were apparent in any of the replicated plots. Visual evaluations of disease severity were recorded at regular intervals throughout the summer.