EFFECT OF SEVERAL ROOT PATHOGENIC FUNGI ON GROWTH OF RED-CLOVER UNDER FIELD CONDITIONS

Effects of Cylindrocladium scoparium Morgan, Trichocladium basicola (Berk. & Br.) Carmichael), Fusarium oxysporum Schlecht., and F. solani (Mart.) Sacc., on survival and growth of red clover (Trifolium pratense L.) plants were investigated in two field experiments using plots of fumigated soil. In the first experiment, the survival of plants inoculated at 5 weeks by dipping roots in conidial suspensions of the test fungi before planting, was significantly reduced by C. scoparium and T. basicola, but not by F. oxysporum or F. solani. In the second, C. scoparium, T. basicola, and to a lesser extent F. solani, reduced survival of plants grown from seed in clay tile microplots for 76 weeks. C. scoparium, T. basicola, F. solani, and F. oxysporum reduced cumulative shoot dry matter (DM) yields by 25-50%, compared with the control microplots. All test fungi caused symptoms of disease on roots, and reduced root DM production in this experiment. Both experiments thus demonstrated that C. scoparium, T. basicola, F. solani, and F. oxysporum are pathogens that affect establishment, survival, and productivity of red clover plants under field conditions.