SUMMER PRUNING CAN POSTPONE RETURN BLOOM TO AVOID FROST DAMAGE OF PLUMS

Late spring frost damage to European plum (Prunus domestica) flowers has been the cause of its irregular and uncertain fruit production in Mazandaran, Iran.
Low temperatures in early winter fulfill the chilling requirements of plums and, after mild temperatures, induce flowering in mid winter.
The objective of this project, which started in 2011 and will be continued until 2015, is to postpone flower induction and delay plum flowering by summer pruning.
Plum trees were topped in late June, July or August to induce new shoots growth.
Results showed different summer pruning dates induced different flowering times next spring, while non-pruned shoots began to flower normally in late February.
Newly-grown shoots from trees pruned in the June, July or August, started flowering 20, 35 and 50 days later respectively.
Second tiers of shoots were affected by apical dominance with lesser shoot length but higher flower numbers.

X International Symposium on Integrating Canopy, Rootstock and Environmental Physiology in Orchard Systems

H. Sadeghi

plum, Prunus domestica, chilling requirement, climate change, frost damage, summer pruning, late flowering

https://doi.org/10.17660/ActaHortic.2014.1058.39