Al Kovaleski September, 2013

Slide 1

Al Kovaleski

September, 2013Effect of timing and intensity of summer pruning on vegetative and reproductive traits of southern highbush blueberryUniversity 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: Plant volume Regrowth 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 JewelSix 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 date11Canopy volume - Emerald12TreatmentWinter volume (m3)Non-pruned1.26aHand pruned1.06b30% June1.01bc30% June+tip0.91c60% June+tip0.68d30% July0.91cRegrowth volume - Emerald13

Flower bud initiation14 Important to:Develop management strategies to enhance floweringRegulate fruit load

First sign of transition detectableFlower bud initiation15

Flower bud initiation16

Flower bud initiation17No differences between treatmentsEmerald Sep 8thJewel Oct 20thLeaf spots - Jewel18TreatmentLeaf spot incidence (%)2011201217 Nov1 Dec21 Dec25 Oct8 Nov23 Nov11 DecNon-pruned70.0a78.8a57.6ab38.3a81.7a88.3a97.5Hand pruned33.3b25.4b54.3ab31.7a56.7bc78.3bc96.730% June43.3ab48.8ab50.9b35.0a61.7b83.3ab95.030% June+tip36.7b48.8ab64.3ab26.7ab53.3bc81.7abc96.760% June+tip36.7b52.1ab84.3a15.0b53.3bc73.3c100.030% July66.7a82.1a67.6ab15.8b41.7c78.3bc94.2TreatmentzDefoliation (%)201120121 Dec21 Dec25 Oct8 Nov23 Nov11 DecNon-pruned15.0aby37.4ab21.7a27.5a68.3a95.0aHand pruned0.0c30.8b4.2ab13.3b31.7b80.0abc30% June6.7bc27.4b10.0ab10.0b36.7b81.6abc30% June+tip5.0bc34.1ab6.7ab11.7b36.7b86.6ab60% June+tip5.0bc52.4a0.0b6.7b25.0b71.6c30% July20.0a50.8a4.2ab13.3b35.0b80.0bcDefoliation - Jewel1919Stem blight20Jewel was not affected

No differences among treatments in EmeraldBerry quality21Average weight - JewelReduction in the 60%+tip2g 1.5gOthers averaged 1.7g

pH, acid and sugar content, anthocyanins, firmnessNo differencesYield - Emerald22TreatmentYield (lbs)TotalPeriods1234Non-pruned14.4NS5.0a6.2NS2.2NS0.7NSHand pruned13.43.7ab6.43.41.130% June12.63.1ab6.83.40.730% June+tip14.63.7ab6.93.20.660% June+tip12.61.5b5.53.61.130% July13.12.0b5.32.41.0Yield - Jewel23

Yield - Jewel24

Acknowledgements25Dr. Darnell and Dr. WilliamsonDr. Olmstead and Dr. Harmon

Florida Department of Agriculture and Consumer Services26

Thank you!