Evaluation of Chemical and Biological Fungicides for the Control of Summer Patch, 1998
Rutgers University
Department of Plant Pathology
DiMarco, J. N.; Majumdar, P. R.; Tredway, L. P.; Towers, G. W.; Weibel, E. N.; Clarke, B.
New Brunswick, NJ
Objective: Fungicides were evaluated for their ability to control summer patch on Kentucky Bluegrass at the Rutgers Turf Research Farm in North Brunswick, NJ. Companion® Biological Fungicide was evaluated in combination with chemical fungicides at reduced label rates.
Method: Turf was established in Sept. 1992 on a Norton loam soil with a pH of 6.4. The site was mowed at 1.5 in., two times per week, and clippings were not collected. Turf was irrigated to prevent drought stress. Fertilizer was applied as 15-0-0 on April 8 (0.21 lb N/1000 sq ft) and April 22 (0.56 lb N/1000 sq ft), and 16-4-8 on July 13 (1.0 lb N/1000 sq ft). Plots were 3 ft x 9 ft and were arranged in a randomized complete block with four replications. Fungicides were applied in water equivalent to 4 gal per 1000 sq ft, with a CO2 powered sprayer at 30 psi, using TeeJet 8003E nozzles. Treatments (trt) 38 and 39 were watered into the thatch after each application with 1 gal water per plot. All treatments were initiated on May 29 when the maximum soil temperature, at a 2 inch depth, reached or exceeded 65°F for 5 consecutive days. Fungicides were reapplied at the appropriate intervals as indicated in the table. Each plot was inoculated in three locations with 25 cc of oats infested with Magnaporthe poae, isolate 73-15, on May 28, 1998. The percent of turf area exhibiting foliar symptoms of summer patch was assessed on Aug. 14, Aug. 31, and Sept. 11. Data was subjected to analysis of variance and means separation by the Waller-Duncan k-ratio t test (k=100), following arcsine transformation.
Results: Summer patch was first observed on Aug. 5 and disease severity increased steadily through Sept. 11. On Aug, 14 all products except the 21.4 oz rate of QST 1713 W, provided a significant level of summer patch suppression. As the disease intensified on Aug. 31, most treatments containing CGA 279'202 50W, Banner MAXX 1.24MC , DAS 0025, Lynx 45W, Eagle 40W, Companion Biological Fungicide, and Heritage 50 WG, continued to provide good to excellent disease control. Excellent season-long control was only obtained, however, with the 4 oz rate of Banner MAXX 1.24MC, Banner MAXX 1.24MC + Primo L 1E, S-7511 G, and Heritage 50WG alone and in combination with Companion, no phytotoxicity was observed.
Companion® is a registered trademark of Growth Products, Ltd., Banner Max ® is a registered trademark of Syngenta Group Company, Eagle® is a registered trademark of Dow AgroSciences LLC, Heritage® is a registered trademark of Syngenta Group Company.