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Al Kovaleski September, 2013 Effect of timing and intensity of summer pruning on vegetative and reproductive traits of southern highbush blueberry 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: Plant volume Regrowth 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 Six 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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Canopy volume - Emerald 12 Treatment Winter volume (m 3 ) Non-pruned1.26a Hand pruned1.06b 30% June1.01bc 30% June+tip0.91c 60% June+tip0.68d 30% July0.91c

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Regrowth volume - Emerald 13

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Flower bud initiation 14 Important to: Develop management strategies to enhance flowering Regulate fruit load First sign of transition detectable

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Flower bud initiation 15

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Flower bud initiation 16

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Flower bud initiation 17 No differences between treatments Emerald Sep 8 th Jewel Oct 20 th

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Leaf spots - Jewel 18 Treatment Leaf spot incidence (%) 2011 2012 17 Nov1 Dec21 Dec 25 Oct8 Nov23 Nov11 Dec Non-pruned70.0a78.8a57.6ab38.3a81.7a88.3a97.5 Hand pruned33.3b25.4b54.3ab31.7a56.7bc78.3bc96.7 30% June43.3ab48.8ab50.9b35.0a61.7b83.3ab95.0 30% June+tip36.7b48.8ab64.3ab26.7ab53.3bc81.7abc96.7 60% June+tip36.7b52.1ab84.3a15.0b53.3bc73.3c100.0 30% July66.7a82.1a67.6ab 15.8b41.7c78.3bc94.2

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Treatment z Defoliation (%) 2011 2012 1 Dec21 Dec 25 Oct8 Nov23 Nov11 Dec Non-pruned15.0ab y 37.4ab21.7a27.5a68.3a95.0a Hand pruned0.0c30.8b4.2ab13.3b31.7b80.0abc 30% June6.7bc27.4b10.0ab10.0b36.7b81.6abc 30% June+tip5.0bc34.1ab6.7ab11.7b36.7b86.6ab 60% June+tip5.0bc52.4a0.0b6.7b25.0b71.6c 30% July20.0a50.8a 4.2ab13.3b35.0b80.0bc Defoliation - Jewel 19

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Stem blight 20 Jewel was not affected No differences among treatments in Emerald

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Berry quality 21 Average weight - Jewel Reduction in the 60%+tip 2g 1.5g Others averaged 1.7g pH, acid and sugar content, anthocyanins, firmness No differences

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Yield - Emerald 22 Treatment Yield (lbs) Total Periods 1234 Non-pruned14.4 NS 5.0a6.2 NS 2.2 NS 0.7 NS Hand pruned13.43.7ab6.43.41.1 30% June12.63.1ab6.83.40.7 30% June+tip14.63.7ab6.93.20.6 60% June+tip12.61.5b5.53.61.1 30% July13.12.0b5.32.41.0

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Yield - Jewel 23

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Yield - Jewel 24

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Acknowledgements 25 Dr. Darnell and Dr. Williamson Dr. Olmstead and Dr. Harmon Florida Department of Agriculture and Consumer Services

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26 Thank you!