Seasonal changes in freezing tolerance of stems and buds of Rubus idaeus L. `Chilliwack', `Comox', `Meeker', `Skeena' and `Willamette' clones were measured from November through March of 1988-1989 and 1989-1990. Eight additional clones were tested in 1989-1990. Canes were harvested from the field, cut into two-bud samples and subjected to controlled freezing tests. Samples were seeded with ice, held at -2°C overnight and then frozen at 3°C/hour. Viability was estimated by visual browning. Vascular tissue at the base of the buds was the least freeze tolerant tissue in these samples. Results of both the 1988-1989 and 1989-1990 freezing tests, indicated `Meeker' and `Willamette' cold acclimated more slowly in the fall than `Chilliwack', `Comox' and `Skeena'. However, in the spring, `Willamette' and `Meeker' were slower to lose freeze tolerance than the other three clones.
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