STUDIES OF WESTERN TREE RUSTS: IV. UREDINOPSIS HASHIOKAI AND U. PTERIDIS CAUSING PERENNIAL NEEDLE RUST OF FIR

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Abstract
Observations in the field and the results of inoculation experiments show that perennial needle rust of fir (Abies spp.), known as Peridermium pseudo-balsameum (Diet. & Holw.) Arth. & Kern, is caused by Uredinopsis hashiokai Hirats. f. and U. pteridis Diet. & Holw. (U. macrosperma Magn.), which complete their life cycles on bracken fern (Pteridium aquilinum (L.) Kühn var. lanuginosum (Bong.) Fern.). The pycnial and aecial states of Uredinopsis hashiokai are described, and for the first time the life histories of U. hashiokai and U. pteridis are presented. The two species are indistinguishable from each other in life history, host relationship, and morphology of most of the spore states; they differ from each other in their geographical distribution and in the morphology of their urediniospores. It remains unknown which of the two species of Uredinopsis represents the perfect state of Peridermium pseudo-balsameum. Uredinopsis aspera Faull proved to be a later synonym of U. hashiokai. U. hashiokai is noteworthy because of its similarity to U. pteridis, and both species are unusual in development of their spore states on fir, particularly in the long periods required for maturation of the aecia, which are produced from localized, perennial mycelium 4 to 11 months after infection in Abies lasiocarpa (Hook.) Nutt. and A. grandis (Dougl.) Lindl. respectively.

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