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The 2009 ASHS Annual Conference

Are Resting Spurs Necessary for Return Bloom in Apple?

Sunday, July 26, 2009: 11:00 AM
Jefferson A (Millennium Hotel St. Louis)
Peter Hirst, Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN
Flowering was studied in ‘Gala’ and Fuji’ apple trees over 2 growing seasons to determine the importance of resting spurs. At bloom, spurs were selected that were vegetative, flowered but had the flowers removed at bloom, or flowered and allowed to carry a single fruit. Buds were samples from each of these spur categories throughout the growing season and dissected to follow the course of flower development. The presence of flowers or fruit on a spur had no affect on the degree or timing of flower formation for either cultivar in either year. Cultivar did not affect the time of flower formation in either year. However there was a dramatic difference in the time of flower formation between the two years. From these data, it appears that return bloom in moderate-sized buds depends more on total tree crop load than whether a particular spur bears fruit.