Fusarium species associated with grassland soils

Abstract

Soils from six grassland sites in North Dakota were analyzed for the presence and abundance of Fusarium species. Samples were collected during the growing seasons of 1979–1981 from an undisturbed sandhills tall-grass prairie, a heavily grazed mixed-grass prairie, two undisturbed mixed-grass prairies, and two cultivated fields. Samples were analyzed using a combination of isolation techniques and isolation media, which yielded 3602 isolates and 20 Fusarium taxa. Ten taxa occurred at all sites and their relative density accounted for 94.2% of the total. Fusarium oxysporum (46.1%) and F. equiseti (22.2%) were the most frequently isolated species. Statistically significant species by site interactions occurred. Recovery of F. acuminatum and F. avenaceum was significantly greater at the mixed-grass prairie sites dominated by blue-grama grass, while recovery of F. oxysporum was significantly greater at the undisturbed sites and significantly less at the disturbed sites. The cultivated sites were characterized by a significantly greater than expected recovery of F. equiseti. Seasonal trends in recovery of certain species were also statistically significant.