1. 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

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

3. 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

4. Plant material 4 Two cultivars ‘Emerald’ and ‘Jewel’ Six year old plants Commercial cultural practices PSREU – Citra, FL

5. 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

6. Treatments 6 30%60%Unpruned

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

8. Vegetative traits 8 Incidence and severity of Stem Blight

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

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

11. R ESULTS TO DATE 11

12. 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

13. Regrowth volume - Emerald 13

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

15. Flower bud initiation 15

16. Flower bud initiation 16

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

18. 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

19. 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

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

21. 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

22. 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

23. Yield - Jewel 23

24. Yield - Jewel 24

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

26. 26 Thank you!