Bulbous / knotty roots…is this a disease or nematode issue?

Was walking through the garden today and noticed these strange roots coming off this Pristine apple that I planted last year. Any thoughts on these strange looking roots?

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I’ve never seen anything like that. The knots are too big to be root knot nematodes. Too numerous to be crown gall. Perhaps damage from wooly apple aphid. Not sure. That’s all of my ideas.


Maybe contact the supplier to inquire if they will replace it. Don’t wait too long as if it’s infecting your soil, it certainly is not normal growth
Kent wa

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Thank you for the response…trying to decide whether to remove the tree and plant another this Spring…hopefully another person will recognize it!

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It was planted almost a year ago Last April…perhaps I will replace it anyway, however.

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What nursery did you get it from

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only things that came to my mind where Root knot nematodes, and Agrobacterium however fruitnut says it’s not those.

whooly apple aphid seems like something it could be. Do you know the rootstock?

@fruitnut are you sure their to big for RKN? i remember seeing some pictures of RKN that had similar sized galls. Although size can be hard to judge from pictures.

anyway, if you opt to replace the tree. I would not plant a new one in the same spot. High chance that whatever it is, is in the soil in that spot now. And thus would reinfect a new tree.

If it where my tree, i would dig up a little deeper root and see if that also has it.


This one came from Stark Bros…was not that impressed with the few I got from them so my next larger batch is coming from Cummins this spring

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Thanks Oscar. I think digging up some roots while dormant makes sense. The tree came from Stark Bros and they don’t tell you the root stock unfortunately…

If it is nematodes we did just have some pretty cold (low single digit) temps here for a week so hopefully they froze…

If planting a new tree I’d consider an entirely different species likely not susceptible to whatever that is…



Looks like woolly Apple aphid to me.
To check for wooly apple aphids…
Take apiece of the root galls from below ground
( above ground portions may have been killed by recent single digits)
Put in a mason jar , add a tsp. Water, sit a yellow sticky card ( for catching insects ) on top of galls seal with coffee filter put in a warm place for a month or so
If woolly Apple aphids the nymphs should appear on card.
Look like this …

To check for root knot nematodes do a bioassy .
Put a section of the galls in new clean potting soil in a container ( mason jar on windowsill ? ) grow lettuce for a month ,remove roots and inspect for galls.


Thank you for the in depth reply! If woolly aphids did make it into the roots is it best to cull the tree? I haven’t seen any above ground but I’m guessing they came from the nursery…

I’ll dig up a bit and see what the rest of the roots look like

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I believe WAA are wide spread , and common .
They live on elms , crab apples, etc.
You are not going to eliminate them by getting rid of that tree.
Here , I mostly see them on seedling apple root stock .
MM 111 - MM106 are mostly resistant .
Natural / native predators will usually keep them in check.
If, one does not kill the beneficial predators with insecticides.


if not seen wooly apple aphids (also called blood lice here) on my own tree’s. But have seen it on tree’s from other people.

Seems more like a nuisance than a real plague. It might cost you a bit of yield. That’s a problem for commercial growing. But for a home grower a few apples more or less usually does not matter that much.

From what i understood, the WAA has a complex life cycle. Living both on the roots and top part of the tree’s. You can partially interrupt that lifecycle by using resistant rootstock (MM series like MM111 or 106, or geneva series)

But some could also survive in cracks between bark as eggs.

Mostly natural predators should keep population in check to a nuisance instead of big problem.

Only thing worth noting is that: above ground feeding spots could be easy access point for other diseases. So you might want to check those. Here such a disease would be Neonectria ditissima - Wikipedia
I have had that and lost a young tree to that fungal disease.

i personally would not rip out the tree. But might go for resistant rootstocks for future tree’s now you know it might be there. Although if a variety i wanted was not available on a resistant rootstock i would still plant it.


Thank you everyone for your help. I’m leaning on replacing the tree…it was the most stunted of all the trees I planted last Spring anyway and didn’t produce much growth its first season. I have an order from Cummins coming next month so I think I can add a new Pristine onto the order and start fresh with a healthier tree. When I dig it up I’ll post some pictures of the root system. Thanks again, appreciate this great forum!