Winter Rainfall Reduces Rest Period of Apple and Pear1

Abstract

Repeated winter rain or water soaking in the laboratory reduced the time required for breaking winter rest of ‘Bartlett’ pear (Pyrus communis L.) and ‘Starkrimson’ apple (Malus domestica Borkh.). Possibly a water soluble inhibitor is leached from the buds.

Effects of Shoot, Root, and Shank Chilling during Rest in Apple and Peach on Growth Resumption and Carbohydrates

“…That apple shoots also must be chilled indicates some changes occur within the buds which enhance effectiveness of root cytokinins. These changes may involve a reduction of growth inhibitors in the bud or bud scales (18,22), and/or a change in sensitivity of the bud tissues (19). Chilling the root or shoot alone is partially effective in promoting budbreak in apple, but the results thus far indicate both must be chilled for maximum budbreak to occur.…”

Evaporative Cooling to Improve Rest Breaking of Nectarine Buds by Counteracting High Daytime Temperatures

“…Since they failed to predict the date of the rest termination for the sprinkled treatment using various models (7), they suggest that other factors are also involved in breaking bud rest when using overhead sprinkling. It still could be that the models used are not accurate enough or that the cause for the response observed could have been other than reduced daytime tem perature, as proposed by Westwood and Bjornstad (9). They claim that leaching of growth retardants would be responsible for better budbreak under rainy conditions.…”

Floral and Vegetative Bud Development of ‘Sungold’ and ‘Sunlite’ Nectarine as influenced by Evaporative Cooling by Overhead Sprinkling during Rest1

“…Recent studies have indicated that differences in bloom date are greater than predicted by accumulation of chill units (2,5). This discrepancy in time required for breaking rest may be a result of leaching of some water-soluble substance(s) from the dormant tree (12). Increased water in the root zone of sprinkled trees may also contribute to the observed response.…”