IT'S A PLUM JOB!

Fruit expert David Patch explains how and when to prune plum trees and experiments with growing one as a cordon, which is not traditional practise

- David Patch

The first key point to remember is plums, indeed all stone fruit, should only be pruned during the spring and summer. This is done to avoid serious diseases such as silver leaf and bacterial canker, which can prove fatal. Silver leaf (Chondrostereum purpureum) is a fungal disease which attacks stone fruit trees, especially Victoria plums, causing the leaves to develop a silvery sheen and affected branches to die back. When these branches are cut there will be dark staining through the centre of the wood. Silver leaf spores are released between September and May, particularly during periods of wet weather, and carried by the wind. It is probably the most common cause of death for stone fruit trees, and the reason why pruning should always be carried out during the growing season when there are fewer spores around.

For young trees, where the aim is to develop a branch framework, a dry, fine spell of weather in late April is an ideal time to prune. It is early enough in the growing season for the tree to respond well to pruning, and put on good growth, but is late enough to minimise the risk of disease spores being around.

As with all other orchard fruit the first steps are to prune out dead or diseased wood, weak growth and branches which are crossing and rubbing. You can then move on to thinning out the centre of the tree, creating an open framework for better air circulation. This is essential, as it helps prevent disease such as mildew and brown rot, and will also help the fruit ripen.

At this point, for young trees, prune the main branches back by about half of last year's growth, to a healthy bud on the outside/underside of the branch. This will encourage a well-spaced framework.