STRIPE RUST, PUCCINIA GLUMARUM, IN CANADA

Abstract

A study was made of the distribution of Puccinia glumarum (Schm.) Erikss. and Henn. in Canada, its specialization, host range, and reaction to environmental conditions. Unlike Puccinia graminis Pers., this rust has a limited distribution, being confined to British Columbia, Alberta, and the western half of Saskatchewan. The natural hosts include a number of native grasses, particularly Hordeum jubatum L. and certain species of Agropyron, Elymus, and Bromus. Wheat and barley also become infected although to a rather limited extent: Stripe rust collected on the above-mentioned hosts has been studied in the greenhouse and has in all cases shown ability to attack wheat varieties. In all instances where identification of physiologic forms was carried out the rust strains were classified as either form 8 or form 13 of wheat stripe rust, the latter form being the more common. The fact that the present authors have collected known physiologic forms of wheat stripe rust on species of Hordeum, Elymus and Agropyron, and have shown that forms 4, 6, 8 and 13 can attack seedling plants of Hordeum, Agropyron, and Elymus species throw a doubt on the existence of the Hordei, Elymi, and Agropyri varieties created by Eriksson.Greenhouse studies showed that P glumarum is extremely sensitive to environmental conditions, particularly temperature. The optimum for uredospore germination is 10° to 12 °C., and for rust development 13° to 16 °C. Varieties susceptible at from 10° to 16 °C. developed resistance at higher temperatures, becoming extremely resistant at 25 °C. On account of the sensitiveness of this rust to high temperatures it seems improbable that it will ever become thoroughly established in Manitoba and Saskatchewan, as in these two provinces the summer temperature is probably too high to permit its development.