Mrs G

Sounds like burr knots. More common on some rootstocks than others. MM111 is known to have a lot of burr knots. Haven't caused me much problems but can be an entry point for borer and other possible issues.

Thanks fruitnut. They look like burrs, almost hairy but thick. I've just never seen anything on my rootstock before. Thanks. I'll watch them. Do they need a spray or should I remove them?

Do I remove the knots, spray with borer spray then do I pile up garden soil to cover the knots (that way they will root?) They surely are ugly. The three apples all have them but the trees are extremely healthy looking.

Mrs G:

You can try cutting them off but they will probably grow back. The long term solution is probably to cover with soil until they root. On the other hand, if you ignore them they will probably be alright.

Raintree, whom I purchased the trees from, sent me a web-site from my state. Fine, but the suggestion from the RI Univ. web site was to use Gallex. It went on to say it is difficult to find it in small quantities. So there you have it. Stuck.

Gallex is for crown gall. That's a disease. Root knots are normal tissue. Could you post a picture?

Gallex is used to treat roots when trees are dug and again before planting. Even if this were crown gall, it's probably too late to treat now.

Don't worry about them. I have a couple trees with tons of them but have never seen problems from lack of vigor or any other problem.

Scott

Not to worry is what I have always heard as well and I believe it.

But I have always wondered why this type of growth isn't a problem, especially when they start covering significant areas of the trunk. Often on big old maples or pepperwood trees you will see the entire base of the tree "girdled" by burl growth (different I know). and i have seen apples with burrknots all around the trunk as well.

In my mind I just see a crazy mixed up pile of cambium tissue, with the trees "pipes" running every which way instead of nice smooth parallel "normal" growth.

It would seem like the tree would suffer from such convoluted flow of nutrient and water...but they don't. So curious as to why not?

Thank you all. When you see an ugly growth starting to girdle a six year old 'Jonagold' apple at the rootstock union (just below the union not on it) you get a little concerned, particularly when it happens so quickly. The burr knots did not exist last year. Also they then appeared on my other apples this summer as well. I think the rain, dampness and fog had something to do with. I agree that I don't understand why the trees will not get stressed. Many thanks all.

I've been managing 111 for decades and never have found the bur knots to be an issue at all although I assume certain pests in certain parts of the country may be encouraged by them. Some varieties of apple such as N. Spy often form burr knots all along the trunk which has never created difficulties for me either.

I once was at a lecture by the Cornell root breeder, Jim Cummins, and he mentioned the superiority of Cornell root stocks for not forming them. When I asked him why I should be concerned about bur knots he really didn't have an answer.

It makes it much easier to produce rootstock when these form freely and anyone can take a 111 plant and create their own root stock factory by piling up soil against a multileader tree (more like a bush). Burr knots are not useful when you're trying to sell a patented root stock for profit.

Thank you harvestman, fruitnut and Windfall, The rootstocks my apples are growing on are: Enterprize on M26; I believe my Jonagold is on EMLA-27 (Raintree is not listing Jonagold as a semi-dwarf for sale currently) and Pristine on M26; is it possible that semi-dwarf rootstocks are more prone to burr knot?

I purchased the Enterprize as a pollinator. Its apples this year were very clean tasting but the skin was like leather.

Enterprise is supposed to improve in storage- wonder if the skin gets less tough because it also has tough skin as grown here.

I don't believe M26 gets burr knots. M27 is not very common and I've never grown it. You really should submit a picture although your description sounds like burr knots dead on.

Apparently M26 can get burr knots although I've never had a problem. Did find this discussion of Dogwood borer and burr knots.

Here is a link that might be useful: borers and burr knots

This site suggests slicing off burr knots or planting deeper.

Here is a link that might be useful: burr knots on M26

Thank you fruitnut, the site was great. I will slice them off, apply borer spray and cover deeper with soil. Whew. The site also covers so many other rootstocks many of which I also have so this information is on my bookmark list. Thanks again. You all have such incredible experience, knowledge and best of applied knowledge. Books are not as worthy! Mrs. G

I don't trust that advice at all. I'd rather have burr knots than open wounds and I've no idea what that advice is based on. Just because someone writes something doesn't make it so and that is not an academic or scientific source as far as I can tell.

Question, Harvestman, even though it is still in the 60's in Newport, RI for at least the next two to three weeks will that time not heal the wounds? Would it be better that I remove them, spray, put on sealer then soil? They are only the size of a dime, except for the burrs on my Jonagold. They are going around below the graft union.

For decades I've managed trees on 111 rootstock into your zone in coastal CT and no pests have ever bothered any of hundreds and hundreds of trees in well over 20 years in spite of ample burr knots.

Strange I haven't seen knots on 26 but I don't manage many trees on that stock (I like a real tree), however, I do prune and provide consultation for a small commercial orchard that has plenty of trees on 26 and the owner has never spoken to me of any problems with burr knots although the trees aren't buried as was crazily suggested in the article FN directed you to.

No commercial grower would bury 26 below the graft union for fear of scion rooting which could eliminate the dwarfing affect of the 26.

All this doesn't mean there was no legitimate reason for their suggestion that I'm unaware of, but before cutting your trees get a second opinion- and a regional one. England has a completely different climate and slew of pests than you do.

Re: Enterprise - I have some in storage now, picked 10/17. Hoping it improves. It's supposed to be a good keeper, but that skin is discouraging.

I'm thinking I may do a lot of baked apples.

Thanks again, to everyone. As for the Enterprise Apples, baking them makes sense. It has such a 'refreshing' taste for an apple, and a taste that lingers. Baking them would be great with the 'leather' jackets they wear! As for the burr knots, I'm going to spray them and leave them alone. I do not want to encourage rootstock growth, why have semi-dwarf trees turn into full size trees? Too complicated.

It's not so complicated. Most varieties of apples are much more vigorous than the apple tree that is the source of M26 rootstocks. This is a clonal rootstock and every single M26 in the world comes as a rooted cutting of the original tree, or a rooted cutting of a rooted cutting and so on.

When you pile up soil against wood above the graft union a differnt tree, the scion the tree is named after, sometimes sends out its own roots that are likely to be much more vigorous than M26. They provide the tree with much more water and nutrients than the 26 could and turns it into a much more vigorous tree.

Planting dwarfing rootstocks too deeply is a common problem in commercial orchards and is often discussed and warned against in guidelines.

As far as spraying the burr knots, that should not be done unless you've identified a pest you are spraying. I keep trying to assure you that such a pest is very unlikely to ever appear.

http://www.extension.org/pages/60605/burr-knots-on-apple-trees

Thanks Harvestman. I have tried to follow directions and planted (according to the suggestion of Raintree) my semi-dwarf rootstock four inches above ground to prevent this. Hopefully they will be fine. I have included the Univ. of RI link of burr knots, this is confusing.

I just read the Rutgers link that FN provided and it was informative for me. Should have read it before I criticized the other link earlier.

Funny how my borers seem to strike well above the rootstock when they attack my apples. I've never identified the specific species, however, as they've been more a nuisance than threat. Sounds like the white latex treatment should be easy enough for you.

Understand that large commercial stands tend to attract greater pest pressure than the kind of home or estate orchards you or I are involved in which may explain why I've never seen a borer use a burr knot as an entranceway.

It probably doesn't help that I have a peach, a nectarine and three plums that have had borers (now dead). I though fruitnut's site was great and helpful, far more than the Univ. of RI. site, which Raintree sent to me. I already had read that one, but thanks all.