Wednesday, November 7, 2007 - 8:00 AM
265-1
Preventative Control of Fairy Ring Associated with Lycoperdon perlatum in Creeping Bentgrass.
Gerald Miller Jr.1, Mike D. Soika2, and Lane P. Tredway2. (1) North Carolina State University, 5456 Viewcrest Way, Apt. 103, Raleigh, NC 27606-3777, (2) North Carolina State University - Dept. of Plant Pathology, Gardner Hall - Box 7616, Raleigh, NC 27695
In 2006 fungicide evaluation trials, two DMI fungicides, triadimefon and tebuconazole, showed potential for preventive control of fairy ring caused by Lycoperdon perlatum. A single spring application of the low and high rates of triadimefon (0.15 g m-2, and 0.3 g m-2) and tebuconazole (0.08 g m-2 and 0.15 g m-2) was evaluated for control of fairy ring on ‘A-1’ creeping bentgrass maintained under putting green conditions. Fungicides were applied at six different times, when 5-day average soil temperatures (2 inch depth) reached 10°C, 13°C, 16°C, 18°C, 21°C, and 24°C. Fungicides were applied in 0.08 L H2O m-2 with a CO2-powered sprayer and were immediately watered in with 6 mm of irrigation. Surfactants were not tank-mixed with fungicides, but stand-alone surfactant (Cascade Plus, Precision Laboratories, Inc.) applications were made to reduce localized dry spot on 3/20, 5/2, and 7/25 at 2.58 ml product m-2. Type II fairy ring symptoms became evident in late May and gradually progressed into Type I and type III symptoms in mid-June. Visual and objective disease severity ratings were taken every 7-14 days. Symptoms started occurring in plots prior to the 24°C application timing, rendering these treatments curative in nature. Significant differences in fairy ring severity were detected in late June, with all fungicide treatments providing adequate control. In mid-July, the low rate of triadimefon was less effective than the high rate of triadimefon and both rates of tebuconazole. Applications made when 5-day average soil temperatures reached 10°C, 13°C, 16°C, and 18°C provided adequate fairy ring control and were more effective than applications made at 21 and 24°C. Area under the disease progress curve values were significantly lower for all fungicides and application timings made prior to the onset of symptom development (10°C, 13°C, 16°C, 18°C, and 21°C).