EFFECT OF GLUCOSE AND BIOTIN ON THE GROWTH AND SPORULATION OF FUSARIUM SPECIES, ESPECIALLY PATHOGENIC AND NONPATHOGENIC ISOLATES OF FUSARIUM-OXYSPORUM

Fusarium spp. often initiate growth slowly on high glucose media in th e absence of added biotin. Among the isolates of F. oxysporum studied, two types were apparent: low sporulating and high sporulating culture s on agar media. Saprobic isolates of F. oxysporum found in sandy soil s usually grew slower than the wilt pathogens from these soils. Within the group of isolates of F. oxysporum formae speciales which cause wi lt in host plants, there were two distinct cultural types that were co nsistently isolated from all infested field soils and from infected pl ants in each field observed. These two types differed in their degree of sporulation and growth on high glucose agar medium without added bi otin; they also could be distinguished based on whether or not they pr oduced a substance easily detected by its odor.