First Report of Downy Mildew Caused by Sclerophthora sp. on Zoysiagrass (Zoysia japonica) in Korea

Abstract

Korean lawngrass (Zoysia japonica Steud.) produces a highly dense, drought-tolerant, and wear-resistant turf that makes it desirable for golf courses, home lawns, parks and sports fields. Because of its cold tolerance, it was adopted in many countries with temperate climates, from East Asia (China, Japan, and Korea) to as far north as Maryland of the United States. In Korea, the demand for zoysiagrass has recently increased roughly threefold between 2003 and 2012 (Kang et al. 2016). During May 2015, zoysiagrass showing typical downy mildew symptoms was first observed in a golf course in Gyeonggi province, Korea, and since then it has rapidly spread into other regions in Korea. Symptoms begin as yellowing of leaves, and develop a raised, tufted appearance, resulting from the shorten internodes of rhizome and an increased number of tillers. A sample of infected zoysiagrass was deposited in the Kunsan National University Herbarium (Acc. no. KNUH 45). Sporangia were hyaline, lemon-shaped to ellipsoidal or obo...