Abstract
Ascospores of P. gaeumannii were released from pseudothecia on moistened needles from April through Sept. with maximum numbers released 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.degree.-30.degree. C, with maximum release at 20.degree. C. Compared with darkness, UV or fluorescent light sources enhanced ascospore release.