Dormant spur-wood pruning severity impacts on vegetative growth, blossom intensity and fruit weight of 'Honeycrisp' apple trees.

The weak growth habit of 'Honeycrisp' apple coupled with its strong tendency to biennial bearing poses a management challenge for apple producers. The potential impact of dormant spur-wood pruning to overcome these problems was tested in three commercial orchards in the Annapolis Valley of Nova Scotia, Canada in a three year trial. Initial trunk cross-sectional area (TCSA) and canopy volume (CV) were measured and treatments were applied in spring 2006. Three levels of spur-wood pruning were compared in a randomized block design with four replications evenly distributed across the range in original tree vigour. Prior to implementing the spur-wood pruning treatments, scaffold pruning was conducted on the treatment trees at each site and pruning weight recorded, the pruning severity varied between orchard sites. The goal was to prune spur-wood densities to appro×imately 40, 60 or 80 spur buds m⁻³ of CV. The TCSA, shoot number and shoot growth were recorded. Each season, dormant maintenance pruning was conducted and pruning weight recorded. Blossom intensity and crop intensity were recorded. Increasing the severity of spur-wood pruning increased shoot number and shoot growth. Blossom intensity and crop intensity biennial rhythms were reduced by all spur-wood removal treatments. All spur pruning treatments enhanced fruit weight. These results, while preliminary, show that spur-wood removal effectively lowered blossom intensity and could become an effective management practice for assuring annual bearing of 'Honeycrisp'.