The pathogenicity of Fusarium avenaceum to wheat and legumes and its association with crop rotations

Abstract

Studies were made of the pathogenicity of Fusarium avenaceum (Fr.) Sacc. to wheat (Triticum aestivum), subterranean clover (Trifolium subterraneum) and barrel medic (Medicago truncatula var. truncatula), and of the effects of crop rotation on field populations of the fungus. F. avenaceum reduced emergence and dry weight of wheat, subterranean clover, and barrel medic seedlings. Infection reduced the height of both legumes but not the height or yield of wheat. The fungus caused a greater reduction in dry weight and height in barrel medic than in subterranean clover. Barrel medic is recorded as a host of F. avenaceum for the first time. The fungus was isolated from the roots of seedlings and from 0.3 per cent of a commercial seed sample. When this infected seed was sown in wheat stubble in crop rotations of fallow-wheat (stubble burnt), fallow-wheat and fallow-wheat-pasture-pasture its incidence in seed increased to 5.2, 6.0 and 10 per cent, respectively Studies on the effects of rotations on the incidence of F. avenaceum in wheat roots and wheat soil demonstrated a relation between crop sequence and population levels of the fungus. F. avenaceum was more prevalent in fallow-wheat-pasture than fallow-wheat.