Effect of Sclerophthora macrospora on Growth and Development of St. Augustinegrass. M. P. Grisham, Assistant Professor, Department of Plant Pathology and Microbiology, Texas A&M University, College Station 77843. R. W. Toler, Professor, Department of Plant Pathology and Microbiology, Texas A&M University, College Station 77843, and B. D. Bruton, Research Plant Pathologist, USDA, ARS, Weslaco, TX 78596. Plant Dis. 69:289-291. Accepted for publication 2 October 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-289.

Internodal lengths were reduced in 10 of 12 cultivars and accessions of St. Augustinegrass infected with Sclerophthora macrospora compared with healthy control plants. Length of leaves and width of leaves and internodes were also reduced in many of the diseased plants. Plant height and fresh shoot weight of St. Augustinegrass cultivar Scott 1081 infected with S. macrospora increased an average of 60 and 48%, respectively, when the fungus was eradicated with metalaxyl. Five-centimeter plugs of Texas Common and Seville sod, systemically infected with S. macrospora, were treated with metalaxyl at transplanting and 90 days later. Fresh and dry weights of roots and tops were greater in treated healthy Seville than in untreated infected controls 138 days after transplanting.

Keyword(s): downy mildew, Stenotaphrum secundatum, turfgrass.