Development of an Advisory System for Grapevine Powdery Mildew in Eastern North America: A Reassessment of Epidemic Progress

Fig. 3. Cumulative ascospore release from New York populations overwintered in New York in 2005-2006, 2006-2007, and 2007-2008. Vertical lines indicate yearly budbreak for Vitis vinifera ‘Chardonnay’ in Geneva, NY. In all three years, a substantial proportion of cleistothecia were able to release ascospores well before budbreak, and many of the cleistothecia dehisced in the field before the availability of host tissue.



Image from Plant Health Progress article:
Development of an Advisory System for Grapevine Powdery Mildew in Eastern North America: A Reassessment of Epidemic Progress