I have read numerous threads on interstems, there is very little long term follow-up from most posters that have done them. What say you, have you done them, are they worth it? How old are the trees that you did interstems on? Would I be better off with G.41 or B.9 alone?
I have about 500’ of row space available but want to plant maybe 50 trees. I am considering MM111/G.41 or MM111/B.9. I currently have several trees each on MM111 and M7. Staking more M7 is doable, I’m too old to plant more on MM111. I want to plant about a dozen different cultivars and about 40 Skillcult seed crosses I planted this spring and would like to graft those to a dwarf rootstock so maybe I can see the results while still young enough to enjoy.
Worth it? I think so.. At least as far as my goals. I wanted smaller trees which I could care for without requiring ladders (nor have to do battle with them to keep them small). As well I didn’t want to have to permanently stake or otherwise support every tree. And of course the precocity of dwarfs.. I hoped that an interstem might provide “the best of all worlds” so to speak.
Of the 21 trees I grafted in 2020, at least some of them are able to stand strong today. Many still have a piece or two of bamboo holding them straight, primarily because of shade from mature forest all around my orchard space though. The trees want to lean to reach the light and I want them to grow straight…
Production hasn’t been stellar so far but they’re getting there.. Deer pressure is intense here and I hope to have an 8’ fence completed soon. So just like every other optimistic orchardist “just wait till next year!”.
I grafted my first interstems this year, so I can’t comment on their long term worth. However, they are my strongest growing trees that I grafted this year.
I did EMLA.111 and B.9. I think I made my interstems too short though. It’s recommended to use at least 10" to get the most of the dwarfing effect. Mine ended up being a variety of lengths. Hopefully, I’ll be able to give you more info in a couple years… =)
I don’t know if it would work in your situation, but I have deer pressure also. Three years ago I put up a 3-D three wire electric fence and it has worked great for the deer ( doesn’t work for squirrels, raccoons, groundhogs or opossums though). Only had deer in the area once and I had turned off the charger and left the gate open. Their tracks showed they went in and out the gate and didn’t cross the fence. It’s cheap and easily changed if needed.
Decide why an interstem is needed and you will have an answer. Interstems can be used to dwarf a tree, to make a rootstock compatible with the scion, to force a vigorous rootstock to produce different sizes of top growth, and even to change the disease resistance of the top.
I am planning on doing a few this coming spring for the first time. Using Bud 9 as the interstem (i have about 6- Bud 9 potted with 12 inch+ new growth) I will be using either Bud-118 or EMLA-111 as rootstock.
It should work fine. Like Bud-10 you have to make your own interstems with G.214. Places like Treco will sell a host of dwarf rootstocks very cheaply. But not Geneva or Bud-10.
I realize that some folks have had issues with G41 and “brittle” graft unions. Luckily though, I have not.. And that includes about a dozen trees blown over and laying pretty much flat during hurricane Helene. I stood them back up and added more bamboo “props” and they’ve been fine. All W&T grafts which likely helps.
I have a few G41 “rootstocks” growing in pots and snip off ~12" sections to use as the interstem piece each year.
Have not tried it myself, but seems to me using an interstem for dwarfing/fruiting would not work. The dwarfing is from the rootstock and using an interstem to accomplish that would only create a thinner spot on the trunk that would be a weak point. Kind of like when pear is grafted onto hawthorn and the pear is much bigger than the hawthorn rootstock. Never tried though, so open to someone saying they did it and it worked long term.
m.27 or b.9 are the traditional interstem varieties. You want ideally a 12" piece and bury the interstem graft union 4" deep. This implies a year in the nursery bucket if you are doing both grafts at the same time or two seasons. Or at least that’s where I ended up. b.118/m.27 is the move.
My interstem trees are too young to provide any anecdotal feedback but interstem grafts work as intended. Trellising killed the interstem market potential and bud grafting is just so cheaper.
All the Geneva rootstocks have some brittleness issues to an extent but the rate of failure is really low so unless you are planting a million trees don’t worry about it. Note that this is only a problem with bud grafts - use whip/tongue and worry about it even less.
That said, you have to stake all the Geneva rootstocks any way and I orient my purchased g.41 trees so that the graft is 180 away from the prevailing wind.
You see interstems used a lot more abroad. A fair amount of large orchards use them.
South Africa likes to put M9 clones on Geneva 778. The huge roots of the G778 maximizes nutrients from poorer soils and gives proven size controlled higher grade fruit.
There are “lots” of low/medium/high vigor apple trees (scions), grafted onto dwarfing rootstocks worldwide. Using only a section of limb from that dwarf cultivar, on top of a “larger” cultivar (interstem). Quite the opposite result it would seem…
This is M111 under ground, a roughly 12" section of G41 (with about 4 to 5" below soil level), and then Aunt Rachel about 7 to 8" above the soil level. The G41 section is as large (or larger) than the scion/cultivar. Grafted/planted in 2020, it’s roughly 2" in diameter. Oh and it’s free-standing and seems quite “strong”.
If any trees of this size set a lot of fruit I’d probably still support them a bit.. For a few more years at least.
I think there is enough history that it is proven to work. Since the tree will reach some equilibrium between the root mass and the tree above, I doubt that M111 will develop an extensive root system like it would if grafted w/o the interstem, but probably will have more root mass under an interstem than a dwarf rootstock that produces a similar size tree. Of course I’m a newbie, have no experience and ultimately don’t know what I am talking about.
My original post was to get opinions as to, is it significantly better than just grafting to a proven dwarf/semi-dwarf rootstock. From what I have read it is, and should do what I want, but will involve more labor and expense. At this point I am going to try it next spring.
An aside on interstems and multigraft trees: Anytime you graft a new variety to a grafted tree you are essentially using an interstem -and if you graft yet another variety to the other new variety you’ve done it again.
Interstems offer the best of both worlds: a sturdy rootstock and a dwarfed, precocious tree. I use seedlings for my rootstocks for genetic diversity. As long as the interstem is about 9” or more, the dwarfing interstem does its job. For an easy to graft fruit like apple, I sometimes make both grafts at the same time, with success. This past July I grafted some Harrow Delight pear scions on to some growing P233 dwarfing stems; in spring I will graft sufficient lengths of these onto pear seedling rootstocks.
Pears often benefit from interstems with our smaller choice of pear rootstocks. Like BA-29C is good on modest production Euro pears. But vigorous Asian pears runt it badly. Burre Hardy is one of the better quince interstems. Comice as well.
