I’m going to attempt to make this a quick short blog post.
I saw on a forum a chap was concerned about his apple tree & confusion as to what was going on with it had caused people to jump to the conclusion it was Canker. Understandably he was concerned but he really didn’t need to be, the tree was perfectly healthy it was just displaying signs of epicormic growth.
What is Epicormic growth?
Epicormic growth is when dormant buds underneath the bark of the tree are stimulated, often through stress, into growth. Often creating a knobbly raised area which i guess to the untrained eye can look a bit sinister. These happen a lot on fruit trees due to the nature of pruning them they are often stimulated to produce new growth. We prune fruit trees to an open shape for ease of picking and to help fruit ripen but left to their own devices they, like all trees want to reach to the sky. When we remove the topmost growth they produce water shoots, strong upright growth from areas that over time will grow to look like this…
As you can see the water shoots have been cut flush over a number of years creating a gnarled knobbly appearance with sunken areas on what is effectively scar tissue, this is fine, the cuts are clean.
As you can see above an old tree over time will develop huge knobbles and still be perfectly healthy. Even a tree with Canker will continue to survive for a very long time so long as it is managed well.
So what is Canker?
Infections on Apple and Pear trees is fungal Canker (bacterial affects stone fruit) Neonectria ditissima is the culprit and causes brown peeling sunken patches on stems, limbs and in worst cases the trunk of the tree. Most times if caught early it can be pruned out easily and new shoots trained in, winter pruning is a good time to do this as winter pruning encourages new growth.
But what does it look like?
Depending on the stage it has reached it can have a variety of similar appearances illustrated below….
The 2 examples above are the early stages of Canker as it progresses it will begin to look like this…
Even at this stage the tree has healthy fruit producing shoots at the end of the limb but the limb will have to go.
Some methods to avoid introducing Canker are
Always clean your tools between pruning different trees, white spirits and a toothbrush are perfect for this.
Practice good hygiene around your trees, don’t leave prunings, fallen apples or leaves lying around, all a source for reinfection. Dont compost, either burn or send offsite.
Make your cuts clean when pruning, sharp tools are a must!
Remember all wounds are a source of infection so when picking fruit don’t pull off the tree, lift and roll. If it doesn’t come it’s not ready. Leaf fall, harvest and pruning are the time your trees are most at risk of infection.