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Al Kovaleski February, 2014 Summer pruning southern highbush blueberries in Florida University of Florida Horticultural Sciences Department

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Blueberry summer pruning 2 No removal of flower buds Long growing season in FL Pruning promotes increased vigor More support for reproductive structures

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Objectives 3 Determine the effects of timing and severity of summer pruning: Vegetative traits: Regrowth Cane breakage Timing of defoliation Incidence of leaf spots Incidence and severity of stem blight Reproductive traits: Flower bud initiation Fruit set Yield Quality of fruit

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Plant material 4 Two cultivars Emerald and Jewel Seven year old plants Commercial cultural practices PSREU Citra, FL

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Treatments 5 No summer pruning control Prune 30% early June Prune 30% mid-July Prune 30% early June+tip Prune 60% early June+tip Detailed hand pruning control www.caes.uga.edu

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Treatments 6 30%60%Unpruned

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Vegetative traits 7 Canopy volume Regrowth Condition of fall foliage Time of defoliation Leaf spot

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Vegetative traits 8 Incidence and severity of Stem Blight

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Reproductive traits 9 Re-growth shoots collected to assess timing of flower bud initiation Late summer until defoliation

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Reproductive traits 10 Harvest Period Yield Fruit quality Total soluble solids Titratable acidity Firmness Average berry weight picturesbychristopher.wordpress.com Labmate-online.com

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R ESULTS TO DATE 11

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Regrowth volume - Jewel 12

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Cane breakage - Freezes 13

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Leaf spots - Jewel 14

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Environmental Conditions 15 2011201220132014

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Leaf spots - Jewel 16

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Defoliation - Jewel 17 No significant defoliation in Emerald until December

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Flower bud initiation 18

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Flower bud initiation 19

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Flower bud initiation 20 Emerald Sep 8 th Jewel Oct 20 th

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Flower bud initiation 21 Important: Develop management strategies to enhance flowering Regulate fruit load Yield! First sign of transition detectable

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Stem blight 22 Jewel was not affected No differences among treatments in Emerald 25% incidence

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Berry quality 23 Average weight - Jewel Reduction in the 60%+tip 1.9g 1.4g Others averaged 1.7g pH, acid and sugar content, anthocyanins, firmness No differences

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24 Yield - Emerald

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Yield - Jewel 25

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Yield - Jewel 26

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Acknowledgements 27 Dr. Darnell and Dr. Williamson Dr. Olmstead and Dr. Harmon

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28 Thank you!