Fusarium Species Associated with Root Rot of Red Clover

Abstract

Summary Of 45 Fusarium strains, isolated from cortical discoloration of the tap and secondary roots and from vascular core of red clover, preliminary tested for pathogenicity on red clover and alfalfa, only 15 isolates, belonging to the five species: F. solani, F. avenaceum, F. oxysporum, F. oxysporum var. orthoceras, and F. sambucinum, has the capability of inciting symptoms of disease. They were tested for pathogenicity on 9 forage legumes in vitro. It was established that in each tested plant species F. solani inhibited root and top growth. F. avenaceum induced rot of roots in all forage legumes, except in white clover and big trefoil. F. oxysporum and F. oxysporum var. orthoceras caused chlorosis of leaves in all host-plants, except in white clover and birdsfoot trefoil. Damages caused by F. sambucinum in red clover, alsike clover, crimson clover, birdsfoot trefoil, and kidney vetch were negligible; it had weak pathogenicity to white clover and no pathogenicity to alfalfa. Disease development was mainly dependend on the time since the infection proceeded. There was significant reduction in the weight of plants, characteristic of infection with F. solani. Contrary to that, an increase of weight was observed in case of infection by F. oxysporum, F. oxysporum var. orthoceras, and partly even by F. sambucinum on the 16th day after inoculation.