Factors affecting the sporulation of Gloeosporium perennans and Gloeosporium fructigenum in vitro

An ability to spore predictably and plentifully when grown in darkness at a constant temperature, is a highly desirable attribute for any organism used to test antisporulant chemicals in vitro. The extreme variability of isolates, and their rapid loss of vigour in culture, resulted in erratic sporulation by Gloeosporium perennans: although sporulation could be temporarily improved by various means, it remained too variable for assessing the antisporulant activity of chemicals in vitro. G. fructigenum, on the other hand, grew vigorously throughout a long series of transfers, and spored reliably and plentifully when grown under the same conditions.