A survey of the diseases of wild rice in Manitoba

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McQueen, David Andrew Ross.
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During the summers of 1979 and 1980 natural stands of wild rice in Manitoba were surveyed for disease. Of the five disease syndromes identified; three, brown spot, leaf and stem smut, and ergot, were already described in the literature; the other two, anthracnose and leaf blotch, have not been reported previously. Fungi isolated from diseased tissues were identified and subjected to pathogenicity testing. In addition to Helminthosporium sativum and Fusarium spp. which are normally associated with brown spot syndrome, Dichotomophthoropsis sp. and Sclerotium hydrophilum were isolated and found to be pathogenic. Collectotrichum sp. and an identified pycnidial fungus were shown to be the causes of anthracnose and leaf blotch respectively. Microdochium sp. was also found to be associated with anthracnose and there is a strong likelihood that it is associated in some way with the disease. Quantitative measurements of incidence and intensity revealed that although brown spot is widely distributed it posed no threat to production. The amount of anthracnose on floating leaves raised questions as to the vulnerability of this stage and what effect pathogenesis of floating leaves may have on the overall development of the plant.