Evaluation of Fungicides for Control of Summer Patch Caused by Magnaporthe poae on Annual Bluegrass

May 18, 2006

Summary: : In a replicated field trial conducted in the summer of 1997 at Arrowhead Country Club, San Bernardino, CA, fungicides were evaluated for control of summer patch caused by Magnaporthe poae. Key results include:

• Monthly preventative treatments of Heritage provided excellent control of summer patch, at both 0.2 and 0.4 oz/1000 square feet, at application volumes of 1.8 or 3.7 gallons/1000 square feet, and applied alone or with the adjuvant Break-Thru. Heritage also performed suprisingly well as a curative treatment, made in late July.
• Banner Maxx in general provided good to excellent control of summer patch. However, Banner Maxx applications at the high labeled rate (4.0 oz/1000) resulted in reversible phytotoxicity when applications were made in hot weather (>90° F). In addition, Banner Maxx did not appear to have the residual activity of Heritage. Based on these results, the best use of Banner Maxx may be at the 2.0 oz/1000 rate, utilized earlier in the season before high temperatures are common.
• The fungicides Eagle and Lynx provided good control of summer patch, but this control was statistically inferior to that provided by Heritage.
• Eagle performance was best when applications were initiated on a preventive basis (on 4/28/97), rather than on a curative basis (on 5/27/97). Eagle performed equally when applied at 0.6 oz/1000 sq ft every 2 weeks, or 1.2 oz/1000 sq ft every 4 weeks.
• Cleary’s 3336 provided control that was statistically superior to the check on most dates, but the control achieved was not commercially acceptable. By increasing application frequency from 14 days to 7 days, control with Cleary’s 3336 would be expected to improve.

Printable version of full report

Principal Investigators: Wendy Gelernter, Ph.D. and Larry J. Stowell, Ph.D., CPPP, CPAg

Cooperator: John Harkness, Arrowhead Country Club

Sponsors: Gary Braness, Bayer; Dave Humble, Goldschmidt; Cristi Palmer, W. A. Cleary; Jim Petta, Zeneca; Randy Smith, Rohm and Haas