Effect of Fungicides and Nutrients Supplements on Summer Patch (Magnaporthe poae).

Dr. J. M. Vargas, A. R. Detweiler, & N. M. Dykema, Michigan State University, 2000.

This study was established on an irrigated annual bluegrass fairway at the Dearborn Country Club in Dearborn, MI.  Treatments were applied preventatively when the soil temperature reached 75° F at a depth of 2 inches.  MACRO-SORB® foliar at 2 oz/1000 ft2, Heritage at 0.1 oz/1000 ft2, and MACRO-SORBÒ foliar at 2 oz /1000 ft2 in combination with Heritage at 0.1 oz/1000 ft2 were applied every 2 weeks on 6/6, 6/19, 7/5, 7/17, 8/3, and 8/14.  Compass at 0.2 oz/1000 ft2 in combination with Banner Maxx at 2 oz/1000 ft2 was applied every 3 weeks on 6/6, 6/26, 7/17, and 8/10.  Banner Maxx at 4 oz/1000 ft2 and Heritage at 0.4 oz/1000 ft2 were applied every 4 weeks on 6/6, 7/5 and 8/3.  Fertility was maintained at ¼ lb. N/1000 ft2 per month, except for the control that was not fertilized.  The percent of diseased area per plot was determined on September 5, 2000, when disease development reached its peak (figure below).

Conclusions

Summer patch disease was light due to a cool and wet summer in 2000.  Daytime temperatures never exceeded 90° F, and nighttime temperatures generally cooled to 65° F or lower.  Under such conditions summer patch, which requires prolonged heat/drought stress, generally is not severe.  Results of this study, although the disease pressure was low, indicated that the MACRO-SORBÒ foliar and the tested fungicides significantly controlled or reduced the incidence of summer patch when compared to the untreated control.  No disease was observed in the plots treated with the combination of Heritage and MACRO-SORBÒ foliar.