SEASONAL WOOD DEVELOPMENT EFFECTS ON FROST TOLERANCE AND FRUIT MATURITY OF RABBITEYE BLUEBERRIES

Abstract

Rabbiteye blueberry flower buds are initiated and differentiated on three distinct wood types - spring growth on old weak growth, spring growth on vigorous 1-year-old shoots, or postharvest late summer/fall growth. Flower buds on spring growth are usually formed and visible by July, while buds formed on postharvest growth flushes appear in late summer and early fall. To evaluate the influence of wood type on cold damage, shoots of `Tifblue' and `Delite' were tagged by season of growth. Following a -10°C freeze in Feb. flower buds on shoots from each growth flush were examined for dead ovaries. Flower buds surviving the freeze were evaluated following a -2° late frost in Mar. Influence of wood type on floral bud and fruit development was determined. All fruit were removed from 5 shoots of each wood type on 2 harvest dates corresponding to early and midseason harvests. Floral buds formed on fall growth were more freeze and frost tolerant than those initiated on spring growth at similar stages of bud development. `Tifblue' was more cold tolerant than `Delite'. Floral buds formed on both spring wood types were earlier to develop than buds formed on fall wood. There were no differences in ripening patterns and quality of fruit removed from spring - new and fall wood. Fruit formed on spring - old wood were later maturing and smaller sized for both harvests than spring-new or fall wood. Postharvest pruning to encourage fall growth may be a cultural means of frost avoidance.