THE OCCURRENCE OF FUSARIUM SPECIES IN CANADA: IV. TAXONOMY AND PREVALENCE OF FUSARIUM SPECIES IN THE SOIL OF CEREAL PLOTS

Abstract

A taxonomic study was made of 12,485 isolates of Fusarium that were obtained from a total of 1674 soil samples taken from two series of permanent cereal plots during the years 1936–1942. Isolates of Fusarium averaged approximately 16% of total fungus isolates. A total of 16 species, varieties, and forms of Fusarium, classified in eight sections of the genus, were isolated. These species, varieties, and forms are F. dimerum Penz., F. merismoides Cda., F. poae(Pk.) Wr., F. sporotrichioides Sherb., F. avenaceum (Fr.) Sacc., F. concolor Rg., F. semitectum Berk. & Rav., F. acuminatum Ell. & Ev., F. equiseti (Cda.) Sacc., F. culmorum (W. G. Sm.) Sacc., F. sambucinum var. coeruleum Wr., F. sambucinum f. 6 Wr., F. oxysporum Schlecht, em. Snyder & Hansen, F. oxysporum var. redolens (Wr.) Gordon, F. solani (Mart.) App. & Wr. em. Snyder & Hansen. The majority of the species isolated were encountered each year. F. oxysporum and F. equiseti, together, accounted for approximately 75% of the total Fusarium isolates. Average concentrations per gram of soil of these two species were approximately 4800 and 2300 'units', respectively. Average concentrations per gram of soil of each of the remaining species isolated were below 600 units. Except for F. dimerum and F. merismoides, the species, varieties, and forms that were obtained from soil have been isolated previously from the basal parts and seed of cereals in the Prairie Provinces.