328 Long-term Impact of Cold Damage on Physiological Performance and Yield Efficiency in Red Raspberry

Abstract

Two test sites pairing perennially cold-damaged portions of fields vs. controls for a 3rd year were assessed. Winter 1997-1998 was very mild and produced less winter injury than the previous winters. We evaluated continued recovery of the raspberry canopy and cane productivity. In contrast to the last 2 years, the previously cold-damaged plots did not show higher levels of cane dieback, percentage of cane dieback, number of dead or dormant buds per cane, and percentage of dead buds at either site. Very few secondary laterals were produced at either site, which supports previous observations that raspberry compensates for winter injury with increased production of secondary laterals. For the first time, the damaged plots actually produced higher yields mainly through a significantly increased berry number per cane at both sites. Floricane leaves in the damaged plots showed higher photosynthetic rates at the green fruit stage and after harvest at site 2. Cane size was similar across sites, although the previously cold-damaged plants had higher berry numbers per lateral. It seems the newly recovered plants in the previously damaged plots had a renewed vigor, working harder to achieve a higher yield. No differences between treatments was detected in leaf nitrogen for a third year, suggesting this may not be a factor in winter injury here. A high population of weevils was observed at one injured site, suggesting a possible interaction with cold damage.