Fifteen isolates representing various genera and species of Diplodia and Diplodia-like .fu ng i were grown on various syn-, I ' thetic media, for study of the effect of pH, temperature, light, [ and vitamins on growth, sporulation, (and stability of morphological characters currently used to delimit" members of the .P haeod id ymous Sphaeropsidales taxon. Fungi tested grew over a wide pH range. A birnodalxresponse in growth at pH levels near , 4.5 and 7.0 was common for most but not~Il isolates tested. The ' p H of the culture medium within-ranges allowing good grO'wth had little influence on mycelial color or general colony appearance. Sporulation was 'influenced by pH, however, apparently more so by 'the buffering system. Although the pH of the culture medium influenced production of fruiting structures and spores, it ' had littl e effect on stabilizing characteristics used in ' classification of these fungi. \ ' Temperatures rang ing from 6°to 39°C had the usual expected effects. Growth of isolates increased as ' tem perature increased, ' pe aked at a range from 2?-') to , 33°C, and. then dropped rapidly to \ form~a skewed curve. Temperature apparently had little influ-I