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An apple tree disorder


By kasy


Burr knots

There is an apple tree in my customer’s garden that doesn’t look healthy. Instead of nice smooth stems you can see something trying to get free, lol.
Here is the picture to help me when I am short of words, lol

I have never seen anything like that before.
Couldn’t find anything similar in few books I have about garden pets and diseases.
So using old good google started to browse an internet looking for similar images.
And came across something called Burr knot.

Then I started to look for more info.
found something saying:

“Apple trees which will grow from cuttings often do so because of burr knots.
Burr knots are clumps of knobbly outgrowths on the branches (usually when branches are 3 years old or more) and these outgrowths are capable of producing both shoots and roots.
Therefore if a sizeable piece of branch with these burr knots, taken just as the leaves are falling, will often root if pushed into the ground and left undisturbed for a year.

Only a limited number of varieties produce burrknots and some more or less than others.
Burrknot quantities seem to be increased when grown on dwarfing rootstocks, or if a grafted trees root system is dying from disease.

A good feature of a modern rootstock is production of burr knots, which allows quicker rooting and establishment, and also makes it cheap and easy to grow-up rootstocks in the nursery.
Layers or stools of the modern rootstocks will often root within a few months in the same way as taking a cutting from a tree with burr knots."

There is the old variety named “Burr Knot” which comes from the South Wales area.
The Welsh Burr Knot is a late summer to early autumn cooking apple.

Here are some more pictures.

But because I am not a scientist nor fruit tree specialist – I can only say I am 99% sure of my find.
And a note to myself – ask my customer if she knows the variety of her apple tree. Definitely a cooking apple – and fruiting happily :)

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i like these knots they give character to the tree ...
thank you for information..
will be interested as you to know your customer’s tree...

12 Feb, 2014


I don't do many fruit tree cuttings but from what I've heard yes it is quite common on some fruit trees.

12 Feb, 2014


Thanks for this Kasy. It's always interesting to learn new things, and I had never heard of this. I've five apple trees in my new garden, but I don't know much about fruit, and so it will be a steep learning curve!

12 Feb, 2014


Very interesting learnt something new again today.

13 Feb, 2014


Glad I could provide some useful information. I learn from the site all the time so I am happy to share some what I know as well :)

16 Feb, 2014


Hi Kasy I have just read your words above about burr knots on Apple trees on dwarf rooting stock. We have 3 pyramids that are over 20 years old at the end of a line of 10 in a wide herbaceous border. 2 of the tall end ones have theses burrs. I have not worried over them because they are very vigorous and sometimes fruit with abandon! The end one has another sinister bark problem, if it encircles the trunk will perhaps kill above that point, I think.

5 May, 2014


Hi Dorjac :) it is sad to read about your ill apple tree... Maybe you could try and do the bridge grafting? It might save the tree.

5 May, 2014

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