|Authors: ||D.E. Deyton, C.E. Sams, J.C. Cummins|
|Keywords: ||Prunus persica, phenology, fruit thinning, bloom, ABA|
Freezes during cold deacclimation of peach buds can drastically reduce yields.
Our previous research showed that sprays of soybean oil in late January or early February can delay peach (Prunus persica) bloom by up to seven days, reducing the potential of freeze damage to flower buds.
Various experiments have associated elevated levels of abscisic acid (ABA) in tree buds and twigs with cold dormancy.
Treatments of water (control), 80/L soybean oil (TNsoy14, 96% soybean oil, a.i.), 1000 mg/L ABA 30025 (Valent BioSciences Corp.) or the combination of the two were sprayed to runoff on 22 February or 10 March to individual trees in five replications of ‘Contender’ and four replications of ‘Nectar’. The ABA was dissolved with ethyl alcohol and stored in the dark until mixed in the spray tank in the field.
The ABA was applied with 5 ml/L Tween 20 as an adjuvant. Flower bud phenology was rated from 18 to 28 March, then trees were rated for open bloom.
The earlier sprays of soybean oil delayed ‘Nectar’ bloom by approximately three days compared to the control, while the latter spray advanced bloom by one day. Spraying 1000 mg/L ABA on either date did not affect ‘Nectar’ bloom date.
The lowest yield occurred on trees sprayed with soybean oil and ABA at the earlier date, however fruit size was not affected.
The treatments did not affect ‘Contender’ flower bud development and may have slightly advanced bloom compared to controls.
The treatments had no significant effects on thinning or yield of ‘Contender’ peach buds.
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