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Degree of susceptibility Host immune Appearance No uredosorl developed. Hypersensitive flecks present, but no hyphre in host tissues. Uredosori abortive and Isolated, surrounded by sharply defined necrotic areas. 2 3 4 Host very resistant Host moderately resistant Host moderately susceptible Host very susceptible Uredosori small and isolated. Surrounded by necrotic rings within a green island, which may be proximally chlorotic. Uredosori medium-sized. Chlorotic patches present. Uredosori large, numerous, in ex• tensive clusters. Large chlorotic areas.Of the imported material so far received, five varieties from Mexico show promise of suitability as sources of resistance for the synthesis of varieties adapted to West African conditions.