A Wilt Disease Op Alfalfa Caused by Fusarium

As stated in the above-mentioned paper (pi), several writers have reported a root rot or wilt of alfalfa with which a species of Fusarium has been associated. Cottam (3) states that the pathogenicity of a root disease of alfalfa in Utah has been traced to the activity of a Fusarium. He describes this disease as being characterized by brown cankerous depressions at the bases of lateral roots, which are entirely destroyed, and he further states that the pathogène attacks both the parenchymatous tissue and the^xylem vessels of the taproot. According to Cottam's observations, the diseased plants serve as centers from which the infection spreads in various directions, often destroying an entire field in a single season. He gives no description of the organism and cites no experiments to prove its pathogenicity. Judging from his description, the disease is evidently not the one under consideration in this paper. Arnaud (i) describes a disease of alfalfa in France that he attributes to Neocosmospora vasinfecta (Atk.) Smith. He emphasizes the presence of the brick-red perithecia on the diseased roots, and apparently concludes that they belong to the fungus that causes the disease. He cites no proof that the disease under observation was caused by a Fusarium, although he considers it to be the same disease as that occurring on cotton. He compares the disease to that caused by Rhizoctonia and does not mention any symptoms that would indicate that he was dealing with a wilt. McCallum (7) discusses a root rot attributed to a Fusarium that attacks alfalfa, tomatoes, melons, cantaloupes, and other crop plants, and states (8) that the most destructive diseases as a group in Arizona are those due to Fusaria. To this group belong the root rots or wilts of alfalfa. These diseases on alfalfa are said to be very destructive, often ruining a large part of the crop. Affected areas in the field