How to Identify and Cure Apple Canker Disease, Neonectria ditissima

Winter is the perfect time to prune your apple tree. But what’s this?! As you are pruning the bare apple tree branches you spot damaged and split bark, and small sunken dark-brown areas with flaky bark. Is this a disease on your apple tree, and should you worry? How do you know if it will kill your apple tree? And what can you do about it?

The cankers on the branches of your apple are most likely apple canker disease caused by the fungus Neonectria ditissima. This fungus can result in apple tree branches dying-back and if it occurs on the main trunk then it can kill even kill your apple tree. If you look closely in the winter you should be able to spot tiny red spheres on the surface of the canker. These tiny red spheres, which I show you in this video, are a great way to confirm apple canker infection and they allow the fungus to complete its life cycle over the winter.

I show you how to recognise early stages of apple canker infection, as well as the more developed older cankers. I also give you advice on how best to prune your apple tree to avoid infection with apple canker fungus. In the UK there are no fungicide spray applications available for home gardeners, so my advice is focussed on chemical-free organic control methods.

Apple canker can become a big problem on wet and acidic soils. If this is the soil type in your garden, you will want to avoid some of the most susceptible varieties such as James Grieve, Worcester Pearmain and Cox’s Orange Pippin. I provide some options for apple canker resistant varieties at the end of the video.

⌚ Timestamps

00:00 Should you worry about apple canker?
00:28 Symptoms of apple canker
01:50 What does apple canker do to your tree?
02:23 Wet and acid soil encourages apple canker
03:02 How to cure apple canker
04:53 Canker resistant apple varieties

Lastly: opinions stated in this video are my own. I have not been paid to sponsor or endorse any of the gardening products I mention or use in this video.

You probably know already that apple canker is a nasty disease that kills your apple tree branches and sometimes kills your whole apple tree. But after you spend just 5 minutes with me, a plant scientist, you will know exactly how to spot apple canker, what causes the disease,

And what apple canker will do to your trees if you don’t treat it. And really importantly, I’ll show you a cure for apple canker. Let’s start with how you can identify or spot apple canker on your apple tree. Apple canker lesions start as dark brown, cracked,

And sunken areas around buds, leaf scars, or wounds. As the canker develops over the next weeks and months, the bark turns even darker in colour and deeper fissures or cracks may form. The bark at the outer edge of the canker, often turns thin and flaky.

As the centre of the canker continues to die off, it appears to recess or sink into the branch. In contrast, the surrounding area of the branch sometimes swells to make an obvious lump on the branch. The sunken cankers frequently have visible rings present in the lesion.

Apple canker is caused by the fungus “ Neonectria ditissima ”. Apple canker fungal infection usually enters via wounds in the bark, such as wounds caused by bad pruning cuts, frost, or other diseases. In winter, you may be able to spot tiny red-brown pinhead-size, spherical balls on the cankers.

These sci-fi-esque balls contain thousands of tiny spores which enable the fungus to continue its lifecycle and spread the disease. So when can you spot the symptoms of apple canker on your apple tree? Shoot dieback and poor branch growth in summer can be caused by canker,

But apple canker lesions are hard to spot when the leaves are on the tree. It’s much easier to spot apple canker in the winter when the leaves have fallen off and the tree is dormant. What does apple canker fungus do to your tree? Apple canker causes serious losses if left unchecked.

Apple canker on the main trunk, or on a young apple tree can kill the tree within a few years. If the disease causes a canker, which girdles or wraps itself around the whole branch, that branch will eventually die. Smaller cankers can weaken branches, and these canker branches are prone to breaking.

Apple fruit themselves can also become infected with the apple canker fungus developing large, circular, soft brown areas known as “ Nectria rot. ” Can the soil affect whether or not my tree gets canker? Absolutely, yes. Wet and acid soils make trees much more susceptible to apple canker.

If you have heavy clay soils, make sure you investigate drainage options before you plant an apple tree. A tell-tale sign of acid soil is if acid-loving plants such as rhododendrons and blueberries, grow well near you. If you have acid soil, consider adding lime which is available

At garden centres for roughly the cost of a coffee per kilo of lime. So now is there a cure for apple canker? Yes. Apple canker has a simple and effective treatment, which I’ll now reveal. Hurray! So don’t destroy your apple trees or rush to burn your orchard! To cure apple canker,

You need to prune out all the cankers present on your tree in the winter. Let’s learn how to prune out apple canker. Start by pruning healthy branches, followed by the diseased ones, cutting back to a healthy bud, or to the trunk. You see this wrinkled ridge at the base of a branch?

Leave this collar in place as it helps the plant to heal, like you can spot here. You don’t want to leave a long stub of dead branch, or torn or ripped pruning wounds. These stubs or wounds will increase the chance of future apple canker infections occurring.

When you remove a stem with apple canker, examine the inside. Healthy stems are pale cream, while infected ones have dark brown streaks. If brown is present, cut again further back to reach healthy, canker-free wood. At this point, depending on the severity of infection,

You might be alarmed by the number of pruning cuts you’ve made. When you prune a healthy apple tree, you only want to remove a maximum of about 15% of the branches in any one year. But with a tree infected with apple canker

Leaving the cankers on the tree is more harmful than the pruning. The cure is harsh, but the tree needs it! Now, commercial apple orchards sometimes apply a fungicidal paint immediately onto the fresh pruning wounds. However, in the UK, there are no fungicides legally available for gardeners to use on fruit trees.

Wound paints do exist, but without the fungicide, their effectiveness is debateable. But don’t worry too much. When you’re pruning your apple trees, just make sure you prune your apple tree in dry weather. Keep those pruning cuts neat and tidy, and clean your tools

With a soft cloth, and soapy water, before and after cutting any diseased branches. Apple trees can quickly form their own protective layer and heal over the wounded surface. Make sure you dispose of diseased apple prunings, by burning or composting offsite. Are there any canker-resistant apple trees?

Resistant varieties include Katy, Merton Russet, and Newton Wonder. There you have it. You’ve spent 5 minutes, but hopefully you feel a little more confident about apple canker. Thanks for watching. Feel free to check out my channel for more ways to keep your plants – including apple trees – healthy.

Wishing you healthy plants, and happy gardening!