Studies onDiplodiaandDiplodia-like fungi: V. Effects of carbon:nitrogen ratio on growth, pycnidia, and pycnidiospore formation

Abstract

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

Studies onDiplodiaandDiplodia-like fungi: VII. Criteria for classification

“…In our laboratory we have attempted to evaluate critically the taxonomic characters that have been used by various authors to classify this group of fungi. The stability and range of variation of the characters have been tested under a number of different cultural conditions and nutrient regimes, including effects of carbon sources (Satour, Vlebster, and Hewitt, 1969a), nitrogen sources (Satour, Webster, and Hewitt, 1969b), pH, temperature, light, and vitamins (Hewitt, Webster, and Satour, 1971), carbon: nitrogen ratio (Webster, Hewitt, and Satour, 1971), natural substrates ; and the natural variation in Diplodia naialensis isolates from grape in California (Webster, Hewitt, and Polach, 1969) .…”