Ascospore germination ofEutypella parasiticaDav. and Lor. occurred over a temperature range of 12 to 38 deg;C. Over 90 of the spores which failed to germinate at lower temperatures germinated within 24ensp;h when placed at 24 deg;C. Percent germination of ascospores varied in the presence of sugar maple and red maple tissue extracts. Germination was best in the presence of outer bark, sapwood, and leaf tissue of sugar maple and red maple and was poorest in the presence of fresh inner bark tissue excised from red maple. Germ-tube development also varied with type of tissue and treatment of tissue. Long, slender, branching germ tubes developed from spores in the presence of nonsterile leaf, bark, and sapwood, whereas short, thick germ tubes developed in the presence of sterilized leaf tissue and sterilized red maple bark. Age of wounded tissue also influenced percent germination of ascospores. Generally germination was higher when pH of these tissues was greater than 5.6. Mycelial growth was best at 29 deg;C. Growth rate was influenced by type of medium. Both sugar maple and red maple bark incorporated into agar media had a significant inhibitory effect on diameter growth of the fungus when compared with growth on nonamended media.
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