Survival of Shot-Hole Inoculum in Association with Dormant Almond Buds. L. M. Highberg, Research Assistant, Department of Plant Pathology, University of California, Davis 95616. J. M. Ogawa, Professor, Department of Plant Pathology, University of California, Davis 95616. Plant Dis. 70:828-831. Accepted for publication 17 March 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-828.

Viable conidia of Stigmina carpophila were found associated with dormant almond buds collected throughout the 1982 dormant season in a commercial almond orchard in Merced County, California. Samples taken from trees where shot-hole disease levels were high during the growing season had significantly more conidia associated with dormant buds than did buds from trees in which disease levels had been significantly lower. In addition, during the 1-mo period between bud swell and bloom, 15- and 10-fold increases in numbers of conidia associated with dormant buds were observed, over previous sampling dates, in samples from trees with high and low disease levels, respectively. Viability of conidia, as determined by germinability, ranged from 65 to 96% for samples throughout the dormant season. In a second study, in which the survival of inoculated conidia on dormant buds was monitored, viability of recovered conidia ranged from 52 to 100% throughout the dormant season. These observations indicate that S. carpophila conidia survive the dormant season in association with healthy dormant buds, thereby contributing to the overwintering population of the fungus on the almond tree.

Keyword(s): Coryneum beyerinckii.