Dinportlre allrghaniensis R. I-Iorner Arnold, sp. nov., is described and illustmted in both the ascigerous and conidial (Phomopsis) states, and the c u l t~~r a l characters are given. This is the first species of Diaporlhr described on the host Betzrln alleghaniensis Britt. I t is distinguished ~norphologically from 1;non.n species of Diapoitl~e by the narrow cylindrical ascus \vith truncate apes and by the narro\v cylindrical-ellipsoid ascospores with variable position of the single septum. I t is a facultative parasite of yellow birch ( B . allegha~zie~tsis) on which it causes an annual bark canlier and foliage disease. The symptoms of the disease are described and illustrated. Methods of Sampling and IsolationT o study the rate of deterioration of B . alleglzaniensis in Ontario, 21 perinanent sarnple plots (P.S.P.) were set u p throughout the commercial range of that species in Ontario

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The structure and development of Melanodothis caricis n. gen., n. sp. (Dothideales, Dothideaceae), a fungus that parasitizes florets of Carex and Kobresia, are described and illustrated. Its relationship to ‘Hyalodothis? caricis’ Pat. & Har., herein considered a nomen dubium, is discussed. M. caricis is reported from the west coast of Canada, U.S.A. (Alaska), Japan, China, and New Guinea, on 14 species of Carex, one Carex hybrid, and one species of Kobresia. In Canada, the florets are infected in the spring at anthesis and the stromata reach their full size the same year, but asci and ascospores do not mature until the following spring. Mature asci were seen in stromata on four species of Carex, C. capillacea from New Guinea, and C. livida, C. pauciflora, and C. sitchensis from Canada, from field collections of mature stromata, and (or) from stromata brought to maturity under artificial conditions. The remaining records are of stromata with immature hymenium. Cultures from ascospores on potato dextrose agar are described.

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Disease symptoms found in nature on yellow birch (Betula alleghaniensis Britt.) infected by Diaporthe alleghaniensis R. H. Arnold, were induced by inoculation of seedlings and saplings with mycelium or conidia. On vigorously growing yellow birch plants, cankers, dead shoots, blackened necrotic petioles and mid-veins of leaves, and leaf spot developed during the inoculation year, and dieback occurred the next spring. Spore tendrils of the Phomopsis state of the pathogen were found on the most recently killed parts of the plants from May until early July. Initial symptoms were most severe on young tissues, and inoculation of shoots caused more damage to seedlings than inoculation of older tissues. The pathogen persisted in the host for several years without symptom expression, or in healed-over cankers. Initial symptoms were more severe on unshaded than on shaded seedlings, but shading increased the ultimate severity of the disease. Soil temperature and soil moisture did not influence artificial infection and subsequent development of the disease. There was evidence that the fungus produces a wilt-inducing agent. The disease was not found in nature on white birch (Betula papyrifera Marsh.), but seedlings were infected artificially. The probable course and importance of natural infection of yellow birch is discussed.