Verticillium wilt of sainfoin

A wilt disease of sainfoin caused by Verticillium Dahliae Kleb. is described, and it is shown that the fungus can penetrate sainfoin seedlings through unwounded roots as well as through ruptures caused by the emergence of lateral rootlets. V. Dahliae was isolated from naturally infected soil only in June, July and August, although another species, V. nigrescens , was obtained throughout the year. Comparative studies of the longevity of cultures of V. Dahliae, V: albo‐atrum and V. nigrescens proved that all are viable for at least 3 years on agar media. On sterilized wheat grains V. Dahliae dies within 8 weeks after inoculation, V. albo‐atrum and V. nigrescens within 12 weeks, while the hyaline variants of the first two remain viable for 6 months. Evidence was obtained that in artificially inoculated soil V. Dahliae persists mainly as microsclerotia. The fungus may also exist in the soil as hyaline mycelium or conidia, but only for a relatively short time. The incidence of this disease in sainfoin is reduced by an increase in soil‐water content, but is unaffected by the application of lime to the soil.