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ARS Home » Northeast Area » Kearneysville, West Virginia » Appalachian Fruit Research Laboratory » Innovative Fruit Production, Improvement, and Protection » Research » Publications at this Location » Publication #310154

Title: Winter shading of blueberry plants in the southeastern United States

Author
item Takeda, Fumiomi
item KREWER, GERARD - Krewer Consulting
item BARNES, RICHARD - Trellis Growing Systems
item BRANSTRATOR, JERRY - Trellis Growing Systems
item SANTOS, BIELINSKI - University Of Florida
item Glenn, David

Submitted to: Journal of the American Pomological Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/30/2014
Publication Date: 3/1/2015
Citation: Takeda, F., Krewer, G., Barnes, R., Branstrator, J., Santos, B., Glenn, D.M. 2015. Winter shading of blueberry plants in the southeastern United States. Journal of American Pomological Society. 69(1):16-25.

Interpretive Summary: The blueberry industry in Central Florida rely on a highly caustic chemical hydrogen cyanamide (HC) to advance the bloom of southern highbush (SHB) blueberries that normally bloom in March by two months. By advancing the bloom to January, blueberries can be harvested from late March to late April, when the price of blueberries is three to five times higher than in May or June. In this study, we determined the effects of two shading techniques as organic and environmental-friendly alternatives to HC application to advance flowering in SHB blueberries. In one study, a shade structure erected over SHB blueberries doubled the fruit set or berries per bud, doubled the number of berries/bud in ‘Primadonna’, but not in ‘Jewel’ blueberry. In another study, a 30 percent increase in early-season fruit production occurred when plants were painted white by repeated applications of white-colored kaolin clay particles. These production techniques offer blueberry growers in Central Florida the ability to harvest fruit during the lucrative marketing period in March and April. Both treatments offer options for organic blueberry producers who cannot use HC, small-acreage blueberry growers who are in close proximity to residential areas, and for mitigating global warming and lack of winter chilling.

Technical Abstract: In Central Florida, southern highbush blueberries are treated with hydrogen cyanamide to replace lack of chilling and enhance flowering and fruiting. Experiments were conducted to determine the effects of repeated applications of processed kaolin particle and flat-top shade structure on blueberry plants during the fall and winter months as alternatives to spraying hydrogen cyanamide on bud viability, flowering, and fruit set. Both shading methods were effective in lowering the bud or air temperatures. Fruit set was increased by shading blueberry plants in winter. Kaolin treatment increased plant yield. The results suggest that weekly application of kaolin product for eight weeks from October to December or shading the plants from November to onset of bloom in mid-January may reduce or eliminate the need of hydrogen cyanamide in some southern highbush blueberry cultivars. Shade structures may also be useful in reducing damage to flowers and green fruit during radiation frost events in late winter and early spring.