Well hopefully we’ve seen the last of the snow here although it has been useful to have some cold weather. Some plants, including apple trees, need a spell of cold weather to go into dormancy and later to kick-start their flowering process, this is called vernalization. Plants with vernalization requirements need a certain number of days of cold temperatures below a certain threshold. The required temperatures and lengths of chilling differ according to the plant species and variety. Without it they can’t prepare properly for the following year and may not flower or produce fruit.
We are busy pruning our apple trees now because it’s easy to see the shape as the branches are bare. We prune out the three d’s: dead, diseased and damaged wood with the aim of opening up the centre of the tree to allow free air circulation, keeping the tree healthy and free from disease and damage.
The aim of pruning is to promote the formation of fruit buds. But it is also a chance to look at the tree to see if it is having any problems. Are there any ominous looking sunken dark spots with shrinking and cracking in concentric rings? Or are there any bright coral or orange raised pustules appearing on dead wood in the tree?
These cheery sounding conditions are some of the more common problems for apple trees. Apple Canker – the sunken pits in the bark, is caused by the fungus Nectria galligena . This is spread by wind-borne spores getting into the tree through wounds in the bark from pruning, cracks and leaf scars (where the leaf has fallen) to name but a few. If you find it, using clean tools, prune out the spur or branch in its entirety. For bigger branches or on the trunk, carefully pare away all diseased bark and wood, cutting back into clean wood and then painting with a protective wound paint, available from your local garden centre. Don’t compost prunings, dispose of them at your local recycling centre or burn. Improving the growing conditions also helps, if the tree is a bit underfed or in wet conditions this will make it more vulnerable. Give it a good mulch and a balanced feed to help it get back to full strength.
Coral spot is the small bright orange pustules you see on dead wood and is frequently a sign that the tree is struggling. This is caused by the fungus Nectria cinnabarina, spores are dispersed by water splash, usually by rain or irrigation and the fungus enters the bark via a wound. Prune out all the dead and dying stems you can see and burn them. Clear fallen leaves and any other plant debris that may be giving a home to the fungus and as per Apple canker give the tree a bit of tlc with a feed and a mulch.
So it’s all about keeping an eye out and catching things as soon as you spot them. Fingers crossed for a bumper crop for us all.
Tricia Harris February 2018