ISHS Acta Horticulturae 165: III International Symposium on Vaccinium Culture
SOME PROBLEMS WITH BLUEBERRY LEAFING, FLOWERING AND FRUITING IN A WARM CLIMATE |
| Author: | C. M. Mainland |
| Abstract:
Approximately 1670 hectares (4,125 acres) of highbush blueberries (Vaccinium corymbosum L.) are grown in North Carolina. The Coastal Plain Area in the southeastern part of the state with sandy, low-pH soils and a shallow water table, accounts for 1620 hectares (4,000 acres). The remaining acreage is located in the mountains of western North Carolina. The commercial blueberry shipping area is centered around the town of White Lake at a latitude of 34° 30'N. This area was considered to be near the southern limit of adaptation for cultivars that were developed in New Jersey when the original planting began in the late 1920s. Success with New Jersey cultivars was reasonably good until the stem canker disease caused by Botryosphaeria corticis soon began to weaken and kill many of the cultivars including the early and profitable 'Weymouth'. Since then a series of stem canker resistant cultivars including 'Croatan', 'Murphy', 'Morrow', 'Angola', 'Harrison' and 'Bluechip' were developed. At least 75% of the parentage of these cultivars came from germ plasm maintained and recombined in the New Jersey breeding program. There are about 63 hectares (156 acres) of rabbiteye blueberries (V. ashei Reade) in the state. The greater tolerance of rabbiteye to fluctuations in soil moisture, higher soil pH and clay soils has made it the species of choice for pick-your-own growers in the central part of the state (Piedmont). Bushes are damaged by low winter temperature in the mountains. The largest concentration of rabbiteye plantings is in the southeastern counties where highbush growers have also planted rabbiteye. Since the rabbiteye cultivars begin ripening almost a month after the highbush cultivars, the grower return is generally considerably lower. In the past, much of this rabbiteye fruit has been picked by machine for processing markets. In southeastern North Carolina, winter chilling averages 1300 to 1400 hours below 7°C (45°F) with a range during the past 15 years of 1294 to 2172. Even the 1294 hours below 7°C during the winter of 1973–1974 should have been enough chilling to satisfy the rest requirement of all highbush blueberries based on the 800 to 1200 hour requirement established by Darrow (2). However, flowering and leafing were delayed | |
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