Selective Medium for Isolation and Enumeration ofPhialophora gregatafrom Soybean Straw and Soil

Abstract

Phialophora gregata, the cause of brown stem rot of soybean (Glycine max), can be isolated readily from physiologically active host tissue but is difficult to recover from senescent soybean tissue and soil. A selective medium was developed for the direct isolation and quantitative estimation of propagules of P. gregata from soybean straw and organic debris from soil. The medium, designated as PGM, contained 20 g of Difco Bacto agar and 129 g of homogenized green beans per liter of distilled water. After autoclaving, 0.8 g of CuSO 4 and 10 mg of pentachloronitrobenzene were added, and the medium was ajusted to pH 5.5 with lactic acid (.)