Can Adrian Baggaley or anyone else advise on the summer pruning of cordon and other forms of trained plums. I have read somewhat contradictory advice.
Some recommend pinching back to 6 leaves during the summer and then pinching any secondary growth back to one leaf.
Others recommend pinching back to 6 leaves during the summer and then pruning back to 3 leaves in August which then obviously removes any secondary growth.
John Kersey
I lost patience with my cordon plums after around eight to ten years of poor crops, cracking and lack of flavour.
Out of sixteen varieties of plum, gage and damson grown as oblique and upright cordons on St Julian A, I could only recommend about three and these are Giant Prune, Belgian Purple and Bradley’s King damson. As cordons only Belgian Purple was dessert quality.
The mode of restricting growth was to nip new growth back to six leaves when the new growth had reached about a foot long, and nipping any new growth from these to one leaf.
After cropping, summer prune back to three buds or three leaves if the buds in the leaf axils are not prominent. I found that the three buds could well be only blossom buds and no extensions or side growth is possible. The shoot will die the following year after blossoming or fruiting.
My favoured system is to modify cordons by not summer pruning and to pull down the new extension growth – good crops will assist this – to form a weeping tree. An increase in flavour and cropping should be noted the following year, but it does require more room.
Once I have the ‘ribs’ on each arm of the fan all growths from then on are cut back to six to nine inches; any frontal or rear growth is rubbed out. I find this gives me a compact fan suitable for a six foot fence panel. When you get to the top you can cut back to the ribs and start again. Pruning is at my convenience and normally in late winter. I tie in the remaining growth at the same time and seal the cuts to prevent silver leaf. This task could be done soon after fruiting if you wish. Any rampant new growth could be tipped or nipped during the summer, only moderate growth is required.
The original recommendation was to prune in late July, when shoots have stopped growing, reducing branch leaders to 8 in and side shoots to 8 in. The leader, the top shoot of the pyramid is left unpruned and tied to a stake and any strong competing upright shoot should be removed. Some people are very successful with modifications on this basic theme. Variations in rainfall, growth and fruit set may upset the ‘rule of thumb practice’. In some years growth may continue in late July especially in a wet summer. If summer pruning is delayed too much, then the vigour of the tree is not curtailed and the compact tree shape will be lost. In the past trees on St Julian A rootstock were fairly vigorous, but now many have experience with trees on the dwarf rootstock Pixy and the vigour problems and complications with pruning are less.