Thx for posting this -- have the same question.

Have a young weeping molten lava crabapple with lots of suckers growing vigorously from the root stock (not weeping). About to prune them out in January.

What's the best pruning technique so they don't sprout again?

I can answer how to get rid of the suckers because they had it on a horticultural show. You have to "snap" them off at the base not cut them. If you cut them it will just cause the eye buds below the cut to start growing. This is not a cure obviously or I wouldn't have posted my question. Brand new suckers will spring up elsewhere around the roots. If you let a sucker get too big it's a real bear to try and "snap" off, so I have to constantly keep after them. But like you I don't want them in the first place. So I hope someone answers this.

To add to this discussion........snapping does indeed work better...when it works, as in, suckers not too big yet. But if one must cut them, do so as a part of your normal dormant-season pruning and then, mid-summer, remove the new ones that have sprouted. Doing so in mid-growing season seems to not lead to immediate resprouting so much. At this point in the growth cycle, the plant is less in the mode (Mood?) of new branch formation.

+oM

Suckering is the greatest problem on cultivars when the understock is too vigorous for the top. Certain rootstocks can be used to reduce the suckering tendency. I don't suppose most people who buy at the retail level would have any way to ascertain what rootstock is used, however. But I do know there are suckering rating guides for ornamental crabs.

For a while I think it was thought that own-root was the way to go. This might not have panned out though.

+oM

calliope, not that I don't believe you, but would you be so kind as to direct me to one of those suckering guides for Malus understock? Of all data I have seen, collected, or heard, I've not heard of that characteristic. Such info would be valuable.

As re: own root and suckering, I have heard this proposed from time to time, but in most cases, it's smoke and mirrors. In certain cases, such as Corylus avellena 'Contorta', growing on own root reducing the problem of suckering...not that it reducing suckering in any way, it's just that the suckers are similar to the parent and therefore not a problem.

When dealing with things that are not shrubs, growing on own root is a classic example of taking a little bit of knowledge and leading the willing to believe what they want to.

As regards why do crabs sucker, for lack of a better answer, it's because it's their nature. They are a plant in the rose family. Many of these sucker. Indeed, those that don't sucker are the exemption (certain Prunus species, although other Prunus species are the worst offenders in this regard). Most do.

My experience has been that the best way to reduce suckering is to bother the root system as little as possible. With certain species, just driving a riding lawn mower is enough to accomplish this.

Vigilance. A pair of pruners is a marvelous thing.

There are certain sprays you can use to help reduce suckering. If you have to ask how to use them, call someone to do it for you.

Danged if I can find the one I was looking at the other night, but I've linked a site below where into the body of the paper is a list of crab varieties and notations as to how many suckers were removed for various cultivars. I kept reading over and over about using M111 rootstock to surpress suckering. That lends a little credence to the suggestions I had read concerning chosing rootstock for this purpose.

It is the nature of the beast on crabs, I have many planted on my property and I have noted some varieties are definately worse than others for throwing up suckers. My daughter, who is a landscaper planted one super dwarf variety at her home and that dude is the worse I have ever seen. I have a few on their own rootstock I'd consider pretty tame however. But they get routine maintenance and part of that is sucker removal. I don't really trust any chemical to spray on suckers, though I know they are made.........but so are tree spikes LOL.

It helps to paste a link, doesn't it?

Here is a link that might be useful: comparisons of traits on crab

As long as we're discussing this, thought I'd mention suckers arising from pruning cuts in the tree crown. Some of these are vertically aligned and heading for the sun. Because of their position, they will often rub against existing good branches and commit other sins of tree structure ruination. Therefor, just as with suckers from the base, they will need to be removed. But a tree's response to branch removal is to initiate new branches (Suckers) so what I try to do is to leave in place any suckers that will themselves be decent branches, sometimes even pruning an ingrowing portion away to a outfacing branchlet or even bud. Basically, try to disturb things as little as possible so as not to provoke the tree's normal response to branch removal. I've pruned many, many flowering crabs and it's really possible to sculpt them into something beautiful to behold. Just a certain measure of restraint is needed, an awareness of how what you're doing is going to cause a reaction. It seems like a type of pruning that some have the knack for, and others just simply don't.

Merry Christmas..........+oM

Thank you for your comments, Lucky. It's always valuable to hear from the real world (people who have experienced it and have made actual observations). Most of the nursery stock I deal in doesn't take a decade to evaluate. I know in a year or two if a plant or "improvement" lives up to the claims. That's quite unlike dealing with trees where mistakes get big and expensive.

I am thoroughly enjoying this conversation about Crabapples. My passion is roses and I am familiar with the suckering propensities of many species roses. I just hadn't connected the dots to other members of the rose family. I have a Pyracantha (rose family) that suckers around a bit too, and I'm sure it isn't grafted. I've been doing a bit of research on Crabapples because the one we do have is the old cultivar Radiant and after 20 years of suffering with apple scab, among other problems, seems to be wearing out. I have noticed that as it's declined the suckering has increased so perhaps a Crapapple in distress will start suckering more regardless of rootstock. Still I want to make the most informed decision I can and hope this discussion on root stock continues. BTW here's a university website that's all Q&A about Crabapples.

Here is a link that might be useful: Crabapples