Silver:

Apple trees that are 20 feet tall are no longer dwarf trees, if they ever were, and should be pruned down to 12 feet or less so that you can reach out and touch all the fruit either from the ground or from your ladder. At this point, that may mean removal of some pretty large branches, especially in the interior of the tree, but you should do it now, in summer, when it will have maximum effect. You want to reduce the vigorous leafy growth of those trees, and summer pruning is the way to do it. Summer pruning will also promote the formation of fruiting spurs, which will improve bloom and fruit set next season.

Fruit tree spikes are often detrimental to apple trees, contributing to bursts of vegetative growth but doing nothing for fruiting. Stop using them, and do not apply any more fertilizers to the trees at this point. Fertilizers will not increase the size of the apples, but thinning the fruit will. Apple trees rarely require supplemental nitrogen to produce well.

Once you have your trees down to a workable and controlled size, you will be able to thin the fruit next season to one or at most two fruits per bloom cluster. Thinning can double the size of apples, and should be done as early in the season as you can identify the largest, undamaged apples in a cluster. That should take care of your size problem.

I know you want to give your apple trees the best care you can, but the care they require is pruning and thinning, not fertilization.

Don Yellman, Great Falls, VA

If I desired a small tree and was getting a large one I wouldn't fertilize at all.

Unless you planted the graft union and it took root above the size limiting stock, I would blame their size more on the company who made them.
A tree should slow down at the specified size. "This tree is a dwarf if you prune the crap out of it." isn't a dwarf in my book. Any tree can be dwarf size if you're willing to keep pruning it to that size.
Making 20' in 12 years isn't slowing down at 10'. I have a semi-dwarf that is between 15-20yrs and it is 17' with no size pruning at all.

At any rate, since they didn't really bear until they reached 20' I would write it off as you have standard sized trees and accept it or replace them. I'm not into making work for myself and keeping a tree that wants to be 20' at the 10' you want it to be will require constant attention.
You didn't give enough information for suggestions on how to prune.
What shape is it pruned/trained to? Where is your bearing wood? How is the light penetration?

I'm a fan of central leader, not a fan of summer pruning for major jobs or major renovations done all at once.
I would do a little heavy dormant thinning each year (I'm guessing your bearing wood is outside of your desired 10' and you don't want to cut off all the future apples in the same year or else all the energy in the next non-bearing year will go to leaves and wood). Then keep after all the vigorous shoots that dormant pruning causes by rubbing them out before they get to any size but keeping one to replace the branch you removed, training that branch to a good crotch and angle, and keeping that branch headed back with yearly summer pruning. If it needs thinned for better light penetration don't allow some of the branches to replace.
Lather, rinse, repeat.
Just imagining what you have I would probably try for it to be completed in about 3 years so that by the time you cut off the last old branch your new branches should be bearing.

I don't think Jonathan is a small apple. My "early" September apples are sizing up now. It's the late October apple that is still on the small side. Perhaps you left too many fruits on the tree.
This is another part of your pruning. Since your tree is overgrowing in size too many fruits is good, to a point. You want enough so the tree is using its energy on the fruit and not leaves/wood, but not so much that it goes into a biennial fruiting cycle.

I've got a Gala tree that I inherited. It is about 15ft tall. Some of the apples are now out of reach of me on my 8ft orchard ladder. Probably on standard rootstock. I plan to cut it back after harvest; about the middle of August. I may do some dormant pruning after that but only to remove excessively vigorous regrowth. I'm expecting about 2-3 yrs of mainly summer pruning to settle it back down at 10-12 ft height.

So you could say I'd vote with mainly summer vs mainly dormant pruning to reduce and maintain a smaller tree for silver2. You may need to do some of both. Main thing is to realize this will be a multiple yr project requiring pruning 2-3 times a yr. If not the tree will resume it's current size.

The Fruitnut

myk1:

You may not be a fan of summer pruning, but you don't say why. I have been at it for 30 years, not that that means I have the system perfected, but I have tried it both ways and now prune my apple trees almost exclusively in the summer. Dormant pruning encourages a spring burst of leafy growth, which is exactly what you do not want and leads only to more pruning. That is a major factor in trees wanting to become 20 feet tall. It is easier to keep them down if you summer prune, and they are more fruitful in the bargain. I have also eliminated most of the central leaders on trees in my orchard and converted to a vase shape, which is easier to contol, thin, spray and pick.

Silver did not necessarily bury the graft unions of her trees, and that is probably not the reason for 20 foot trees. Nor is the nursery that sold them at fault. In all probability, she has trees on semi-dwarf rootstocks, such as M-7, M-106, or M-111. There is considerable difference in the vigor of scion varieties, but many of them will easily grow a 20-foot tree on a rootstock classified as semi-dwarf. Fully dwarfing rootstocks, which normally require external support, are a different matter. If I did not give my trees any pruning attention at all, I would have quite a few over 20 feet or more, and nearly all my trees are on M-7 or M-106.

I have never killed or permanently damaged a tree by summer pruning, even when it was extensive, and I don't think Silver should be discouraged from trying it.

Don Yellman, Great Falls, VA

jellyman,
I mainly limit my summer pruning of live tissue to rubbing and pinching. If I happened to miss some woody growth that needs removed the sheers aren't off limits but it has to be small enough for sheers.
I have mental issues with grabbing a saw in summer except for repairing damage. Plus I don't want to lose the apples doing major summer pruning causes on everything but summer varieties. Losing a branch of apples may not hurt when you have many dozens of trees, but for those of us with only a few trees it does.

And don't forget winter comes a lot earlier in most of VT than it does for you or me. These apples aren't ripe until September. VA is much different than VT.
A 20' tree that hasn't been pruned in 6 years most likely is only bearing on the outside.
Pruning it all now means no fruit this year with no guarantee of fruit next year. Waiting until mid-September after the fruit is picked increases the risk of winter damage which is a higher risk in VT than it is in zone 6/7.
I've noticed the biggest fans of summer pruning for everything are where winter is a minor event.

Yes dormant pruning causes a burst of growth and that is easily rubbed off.
My goal would be branch replacement not simply cutting back and hoping some spurs come out of the old non-bearing wood. That burst of growth would make the branch replacement go quickly.
After it is pruned back I said that summer pruning should be used to keep it in check. That summer pruning would be minor enough so no apples are lost and the risk of winter damage isn't increased.

I didn't say she necessarily buried the graft. I simply offered that as a possibility, and it is a common cause for grafted trees planted by unknowing homeowners to overgrow to standard size. I don't think that's possible on the 2 dwarfs I have but I've seen some dwarfs grow to standard size where that was the cause.

If she was sold a "dwarf" on semi-dwarf roots and that variety is one that will grow to standard size on that rootstock it is indeed the fault of the nursery who misrepresented them.
I'm not into all that rootstock stuff, I don't even know or care what my trees are on. I'm just an average homegrower who expects a 10' tree when I'm sold a 10' tree. 12' or even 15' for a dwarf I would say vigorous tree (which Jonathan is). But full grown standard sized "dwarf" in just 12 years with a size pruning at 6 years says something was done wrong or else those fruit tree spikes are some potent stuff and didn't have that effect the one time I was given some.

Thank you for your advice. I will start on some pruning to see if I can thin and shorten the trees. Is it too late to thin the apples so they will grow larger? The both fruited on the inside and outside branches. It has been such a long wait to see fruit on these trees. Jonathan apples, at least when we used to be able to buy them locally, which was probably close to eighteen years ago were about the size of macs. I did do something right when I put them in, as I put them on top of a slight bank, so they have good drainage, just makes it tough to work on the side of the trees that are on the bank. When I paid a local nurseryman to prune them, he did it in the dead of winter and he took them down to about twelve to fifteen feet. I would prefer to prune in the summer as it is a whole lot more stable on the ground. Floundering around in several feet of snow, even though you can see your branches better, is not to be desired. I would dearly like to get some good fruit off these trees, as I said, my husband has been waiting for years for this to happen. After all this time he had kind of given up on them. But he is eyeing the trees with relish at this point. And is quite excited over the prospect of getting some of the apples. The Jonathan, I guess, went out of favor due to, I guess, being harder to maintain and subject to more diseases. But they used it for many crosses, but the flavor is just not there.
Thanks again, and hopefully thinning at this late point will help with the development of the remaining apples.

You can thin the small fruits off now and that will help the larger ones get larger.
I get hit so hard with June drop, storms and bugs that I rarely thin for any other reason.

Whether eventually or exclusively you definitely need late summer pruning to calm the tree down if it was over 15' at 6 years.
I don't know if pruning wood for height along with the attached apples right now will have the result of increasing apple size, but if it does that sounds like a good option since you have interior fruiting and you'll be thinning fruit anyway.

My McIntosh (the ones that aren't bugged) are right at 3" now which when ripe should make them the size of the "Large Granny Smiths" from WA that are in the local stores. The GS were the same size as Delicious which were much larger than some other kind they had.

When you planted the trees you must have inadvertently covered the graft at the top of the MM111 or M9 Rootstock. If I'm right and that's what you did, then the tree will grow as a standard tree, not a dwarf. Also fruit tree spikes can contribute to the onset and spread of fire blight, and thus should never be used on apple trees. So you're lucky you have a tree at all. From now on, in January prune your tree to the desired height, and you should not have further difficulties. I disagree with summer pruning as that can also contribute to disease onset. Good luck.

Carla,

First of, this thread was last posted in 2008.

Secondly, this is the first time I've heard that tree spikes can contribute to the onset and spread of fire blight. Can you please elaborate?

Where did you get an idea of summer pruning contribute to disease on set?

People prune apple trees in the summer to slow down the growth and encourage fruit bud forming all the time.