Help ID strange bulge on young apple tree?

Hello, I’m still fairly new to gardening, so I hope someone can help me figure out what’s going on with two of my young apple trees. I’m mostly concerned about whether these might be problems that could become serious and/or spread to other trees in my garden.

One is a maypole crab on dwarf rootstock, and the graft union (always quite noticeable) has swollen hugely.

The other is Wolf River on semi-dwarf, with a small, smooth bump partway up the scaffold. Would it be best to prune off this branch entirely as a preventative measure or wait and see how it develops over the next year?

Any advice or suggestions would be greatly appreciated!

-S

I would almost say it’s just a graft union bulge, but I’ve not seen any quite like that.
Someone else who has seen more and has more experience will probably chime in what they think.

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Yes, it did start out looking like my other Apple tree’s graft unions; bulging, but not excessively. But at some point when I wasn’t looking, it got huge and weird. The most obvious difference between it and my other apples is that it’s on dwarf rootstock while the others are on semi dwarf. I think it still looked pretty normal when it flowered in the spring.

This is the small bump on the Wolf River semi dwarf:

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It’s common to get a bulge on dwarf stock. I’m not sure what causes it. I was out pruning today and I was noticing some of my older dwarf trees with bulges almost the size of soccer balls.

These trees are 20 years old and still going strong, so I don’t think there is any reason to be concerned.

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Thank you, that’s a big relief to hear! Any insight into the “pimple” on my other tree?

Some apple trunks are absolutely covered with those pimples. I have often seen them with burr knots so assumed they were burr knots that did not get as far along in their development. Anyway nothing to be concerned about.

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Thank you!

A IE mulberry that I grafted on to a wild alba rootstock has a pronounced bulge at the graft union, maybe I’ve discovered a dwarf rootstock for mulberries. :slight_smile:

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Those swollen graft unions are considered a defect by the rootstock industry and when looking at rootstocks that are susceptible to the problem EMLA 26 is probably at the top of the list. It is definitely made worse the higher the union is above ground.
Ive been using thousands of m26 for a lot of years and the oldest (36 years) have some pretty big collars on them now but I cant say that the trees have been harmed in any way by the swelling.

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Interesting! For reference, my tree is on G41.

Yes, with the exception of G11 all the Geneva stocks are advertised as burr knot free.
It may be that the tree in this picture is just a unique case being encouraged by the extra distance between soil line and union.