Culture Conditions and the Formation of Perfect State of Helminthosporium oryzae, Cochliobolus miyabeanus

Abstract

The optimum culture conditions for pseudothecia formation by Cochliobolus miyabeanus have been determined: Sachs medium with rice straw, 20-24C (development was slower at 20C), pH4.65-8.10 (in the case of Czapek's agar-no carbon source medium with rice straw: pH3.7-5.9), Sachs medium with gramineous crop or weed plants added showed fairy good pseudothecia fromation as well as with rice straw. As a natural medium for perfect state formation, rice straw decoction agar (50g, 10g, or 1g/l) or potato decoction agar (150g, 30g, or 3g/l) was adequate when a rice straw was placed on the agar surface. Use of rice seed coats on Sachs medium gave scanty pseudothecia formation.