Seasonal availability of Phaeocryptopus gaeumannii ascospores and conditions that influence their release.
Ascospores were released from pseudothecia on moistened Pseudotsuga menziesii needles in Apr.-Sept., with max. numbers during June and July. Pseudothecia on 1-yr-old needles released 10 times more ascospores than did those on 2-yr-old needles. Moistened pseudothecia released 75% of available ascospores within 20 min and all within 4 h. Ascospores were released at 5-30°C, max. at 20°. Compared with darkness, UV or fluorescent light sources enhanced ascospore release.