Slide 1

Al Kovaleski

February, 2014Summer pruning southern highbush blueberries in FloridaUniversity of FloridaHorticultural Sciences Department1Blueberry summer pruning2No removal of flower buds Long growing season in FL Pruning promotes increased vigor More support for reproductive structuresObjectives3Determine 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 blightReproductive traits: Flower bud initiation Fruit set Yield Quality of fruitPlant material4Two cultivarsEmerald and JewelSeven year old plantsCommercial cultural practicesPSREU Citra, FL

Treatments5No summer pruning controlPrune 30% early JunePrune 30% mid-JulyPrune 30% early June+tipPrune 60% early June+tipDetailed hand pruning control

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Treatments6

30%60%UnprunedVegetative traits7Canopy volumeRegrowthCondition of fall foliageTime of defoliationLeaf spot

Vegetative traits8Incidence and severity of Stem Blight

Reproductive traits9Re-growth shoots collected to assess timing of flower bud initiation Late summer until defoliationReproductive traits10HarvestPeriodYieldFruit qualityTotal soluble solidsTitratable acidityFirmnessAverage berry weight

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Labmate-online.comResults to date11Regrowth volume - Jewel12

Cane breakage - Freezes13

Leaf spots - Jewel14

Environmental Conditions152011201220132014Leaf spots - Jewel16

Defoliation - Jewel17

No significant defoliation in Emerald until December17Flower bud initiation18

Flower bud initiation19

Flower bud initiation20Emerald Sep 8thJewel Oct 20thFlower bud initiation21 Important:Develop management strategies to enhance floweringRegulate fruit load

Yield!

First sign of transition detectableStem blight22Jewel was not affected

No differences among treatments in Emerald25% incidenceBerry quality23Average weight - JewelReduction in the 60%+tip1.9g 1.4gOthers averaged 1.7g

pH, acid and sugar content, anthocyanins, firmnessNo differences

24Yield - Emerald

Yield - Jewel25Yield - Jewel26

Acknowledgements27Dr. Darnell and Dr. WilliamsonDr. Olmstead and Dr. Harmon

28

Thank you!

TreatmentLeaves containing at least one leaf spot (%)

2011---17 Nov1 Dec21 Dec

Non-pruned---70.0ax70.0a56.7ab

Hand-pruned---33.3b16.7b53.3ab

30% June---43.3ab40.0ab50.0b

30% June+tip---36.7b40.0ab63.3ab

60% June+tip---36.7b43.3ab83.3a

30% July---66.7a73.3a66.7ab

2012--25 Oct8 Nov23 Nov11 Dec

Non-pruned--38.3a81.7a88.3a97.5a

Hand-pruned--31.7ab56.7b78.3ab96.7a

30% June--35.0a61.7ab83.3ab95.0a

30% June+tip--26.7ab53.3b81.7ab96.7a

60% June+tip--15.0b53.3b73.3b100.0a

30% July--15.8b41.7b78.3ab94.2a

20133 Oct17 Oct31 Oct14 Nov29 Nov12 Dec

Non-pruned63.3a95.0a99.2a100.0a100.0a100.0a

Hand-pruned45.0ab82.8ab92.5ab98.3ab100.0a100.0a

30% June24.2c68.3b88.3b91.7c100.0a100.0a

30% June+tip26.7bc78.3ab90.8b95.0bc100.0a100.0a

60% June+tip23.3c66.7b86.7b92.5c100.0a100.0a

30% July32.5bc73.3ab90.0b94.2bc100.0a100.0a

TreatmentDefoliation (%)

Early OctMid OctLate OctMid NovLate NovMid Dec

Non-pruned27.5a47.5a42.1a47.5a55.0a66.9a

Hand-pruned12.5b29.2ab23.3b31.3b27.2bc56.1ab

30% June7.5b14.2b20.4b19.2bc26.7bc51.1b

30% June+tip7.5b20.0b20.8b22.5bc28.3bc57.2ab

60% June+tip6.7b13.3b12.9b13.8c18.6c53.3b

30% July11.7b24.2ab21.3b25.8bc35.0b61.7ab