A total of 1910 fungal isolates were cultured from bark of American beech trees (Fagus grandifolia Ehrh.) in New Hampshire, Michigan, Ohio, and Pennsylvania. Nearly two-thirds of the isolates were members of the Fungi Inperfecti. The most frequently isolated species were in the form-genera Alternaria, Aureobasidium, Cladosporium, Coniothyrium, Fusarium, Geotrichum, Nodulosporium, Penicillium, Phoma, Rhinocladiella, and Trichoderma. While directional aspect (N, E, S, W) of the bole had little effect on isolation frequencies of most fungi, the kind of culture medium used had significant effects. With the exception of Nectria coccinea var. faginata Lohm., Wats., & Ay., all fungi were isolated from noncankered bark of beech trees in New Hampshire with and without beech bark disease. Healthy bark of temperate hardwoods has a community of organisms, including fungi, associated with it (Bier, 1964). Several workers have isolated fungi from bark of hardwoods, often to investigate the antagonism of these fungi to bark pathogens. Bier and Rowat (1962) found species of Aureobasidium and Epicoccum purpurascens Ehrenb. : Schlect. to be the most common fungi in the caulosphere of both black cottonwood (Populus trichocarpa Torr. & Gray) and willow (Salix sp.). Species of Alternaria, Epicoccum, Fusarium, Penicillium, Phoma, and Trichoderma were most frequently isolated from healthy bark of sugar maple (Acer saccharum Marsh.) by Kliejunas and Kuntz (1974). Garner (1967, and personal communication) isolated from the bark of quaking aspen (P. tremuloides Michx.) species representing 50 genera of fungi, and, of yellow-poplar (Liriodendron tulipifera L.) species of 22 fungal genera. Over 90% of the isolates from twigs of red alder (Alnus rubra Bond), black cottonwood, broadleaf maple (Acer macrophyllum Pursh), and willow were species of Aureobasidium; other fungi isolated from these trees included species of Epicoccum, Rhizopus, and Penicillium (Sivak and Person, 1973). Part of the resistance of black cottonwood to Hypoxylon pruinatum (Klotzxch) Cke. is due to the microflora of the tree's bark (Bier, 1964). Similarly, the microflora of peach bark probably contributes to the resistance of peach trees [Prunus persica (L.) Batsch.] to Leucostoma cincta (Fr.) v. Hohnel (Wensley, 1971). However, in a study of a third canker disease of maples, Kliejunas and Kuntz (1974) did not find evidence of antagonism by the caulosphere microflora of sugar maple against Eutypella parasitica Dav. & Lor. To understand the interactions of caulosphere microorganisms and to determine whether they may contribute to a beech tree's resistance to the agents of beech bark disease, a necessary first step is to catalog the microorganisms associated with the bark of American beech. To prepare such a catalog, caulosphere fungi and other microorganisms were isolated from bark of American beech trees in New Hampshire, Michigan, Ohio, and Pennsylvania during December, 1976, and January, 1977.
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