Interstem aka interstock Pear Grafting

As grafters we all eventually come to the conclusion that some things are easier to graft than others. Apples such as Winter Banana are highly compatible grafts with most any apple tree rootstock or fruiting apple tree for that matter. Frequently grafters who learn this trick may learn to use Winter Banana apples as an Interstem for other things, in extreme cases even pears. It is possible to graft pears to apple or apples to pears but that’s not the scope of what I’m trying to accomplish with this discussion. I have some particularly stubborn wild callery pear rootstock that have rejected several grafts ranging from chojuro , kiefer, to madame boutant. I’m thinking of attempting to use clara frijs as an interstock (see this description http://www.ars-grin.gov/cgi-bin/npgs/acc/search.pl?accid=%20PI+105193). If your not familiar with this concept read this article http://www.uky.edu/Ag/Horticulture/Geneve/teaching/plantpropwebpages/grafts/graftingtermsinterstem.pdf and this article http://www.orangepippintrees.com/articles/fruit-tree-advice/interstem-rootstocks. I know interstocks effect both fruit size and height (see this article http://www.inflibnet.ac.in/ojs/index.php/IJFS/article/view/2156). I’m very hopeful someone in this forum grafts hawthorne , quince , or similarly incompatable pear rootstocks and will know what makes the best interstocks for difficult to graft pears.

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Clark. About 5-6 years ago I grafted a Mooglow, Orient, and Ayers scions to a volunteer seedling Callery. All three appear to be compatible and fruiting up nicely. I do many other intestems but that is not the information your looking for. Good luck, Bill

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Auburn,
I think I will graft these genetically unique callery pears over to Clara frijs and see what happens. The trees have large trunks so if I can get the grafts to work they will produce pears in 2-3 years. Douglas seems to graft very easily as well. The Douglas had 100% take rate on 5 small callery I tried last year.

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I cannot offer any help on the pears, but I have a plum that has rejected 24 of 26 grafts of 9 different varieties. Only 2 grafts (the only 2 made) of 1 single variety remain. By “rejected” I mean truly rejected, not just scions that died or never broke.

I cannot remember right now what variety was successful, but this post reminds me that maybe using that variety as an interstem may be a solution.

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Appleseed70,
That is exactly the situation. I wish further work had been done with Clara frijs and I knew for sure it is as good as I think it is. The ars grin site says "‘Clara Frijs’ is an old Danish pear, and still one of the most popular varieties in Denmark. However, it does not seem to have had any circulation in other countries. This variety was first described by J. A. Bentzien in the Danish garden journal, Dansk Haugetidende, in 1858. Several trees of Clara Frijs were found by Count Carlsen in the Danish village of Skensved, but its true origin is unknown.
The fruit of Clara Frijs is of medium size, about 115 grams (4 oz.) per fruit. The skin is very smooth, and highly resistant, if not immune, to russeting. The ground-color is bright green which later becomes a uniform yellow. It occasionally has a pink cheek. The fruit is fine in quality, very juicy, sweet, with good flavor. Doyenne du Comice and Clara Frijs are the highest priced pears in Denmark. In the variety trials at Blangstedgaard, Clara Frijs has been one of the most productive varieties, although it shows a tendency toward biennial bearing. Fruit thinning is often necessary. Its picking date is mid-September, some three weeks before Conference.

Clara Frijs is compatible with quince, and has for many years been commonly used as an interstock for incompatible pear varieties grafted on quince. This variety keeps well for about two months at 0?C. Longer storage reduces dessert quality. Fire blight is not known in Denmark, therefore nothing is known about its susceptibility to this disease. Most of the Clara Frijs trees in Denmark are infected with vein-yellows virus. However, virus-free material is being propagated by the State Department of Plant Pathology. Propagation material should be available within two or three years.?J. Vittrup Christensen, Blangstedgaard, Odense, Denmark. from: American Pomological Socitey, Fruit Varieties Journal, 1962."

I’m suspecting based on that statement and my own experience we don’t know what we have. The part were it says " is compatible with quince, and has for many years been commonly used as an interstock for incompatible pear varieties grafted on quince" I think is an understatement. I grafted ayers, Madame Boutant, Clara frijs, clapps favorite, and 2-3 other varieties I don’t recall on a full grown callery. As is typical they all greened up and began to grow away. The Clara frijs and clapps favorite did not die and the others did due to compatability problems. Typically I graft trees like that with 20+ scions and then I cut away those that don’t take. I use so many grafts to avoid loosing a years growth. Similarly the whip grafts I did were equally as successful. I suspect Clara frijs may be to pears what winter banana is to apples it’s just to early for me to know for sure.

I’ve read that interstems for quince, hawthorne, and mountain ash that the pears Beure Hardy, Old Home, Anjou, and Comice are the most successful types used as interstems. It might pay to have some interstem scion trees on hand. I’ve had great success with clapps favorite and clara frijs grafting on stubborn wild callery trees. I will graft more this year though should also mention my douglas pears had a 100% take rate on all callery I tried them on which was 5. Some pears are easier to graft than others. One study that documents hawthorne, and mountain ash interstem pear varieties can be viewed here http://horticulture.oregonstate.edu/system/files/ond100203a.pdf. Beure Hardy is used as an interstem for quince as noted here in a study done by the usda http://portal.nifa.usda.gov/web/crisprojectpages/0423049-cold-hardy-and-fire-blight-resistant-quince-propagation-rapid-multiplication-and-field-trials.html. To further backup the Beure hardy as an interstem for quince note it being used here Maple Grove Nursery - Rootstock. This is another interesting article on rootstocks and interstems if you have the time http://www.orangepippintrees.co.uk/articles/rootstocks-for-pears

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I just have to say that posts like this (and the reference articles provided) is what makes this site and the whole fruit growing hobby so great for me. While your level of research and depth of knowledge mostly remind me how far behind I am in my own understanding, it also shows just how complex and fascinating this hobby can be. Men and women (much like you and the other experts on this site) can spend a lifetime researching and experimenting with things like you are working on, and to me that makes the hobby so much more interesting. A person can take our little hobby as deep and far as the imagination and desire will allow, and that’s pretty neat. I may never amass that depth of understanding and experience because I may be happy with more simple projects and more basic experiments, but its nice to read these kinds of posts and know that this hobby has something for everyone- from the person who just wants to plant a couple apple trees and learn the right sprays and things to get nice apples, all the way to the person who wants to research and locate an obscure variety of fruit tree that he/she can use as an interstem to make incompatible trees be grafted together. Anyway, just wanted to say that even though its over my head, its neat to see the complex pursuits of others.

Not to “dumb-down” your post and I know its not relevant to your question, but I did want to throw in that thanks to the advice and assistance of people here, I was able to graft 4 different varieties of fruiting pear trees to a Bradford Pear “stump” and it is my all-time favorite project. That Bradford pear was a big tree with big roots but produced nothing of value. There is something wonderful about me being able to take advantage of that useless (to me) Bradford pear tree’s time on earth and its root structure and convert it into something that will be producing a varieties of very useful fruit in a very short time. (I say in a short time because all 4 grafts grew incredibly large in their very first year!) Sorry for hijacking the thread…just wanted to say I enjoy these complex projects and also boast a little about my own little Callery pear project- though I know it has nothing in common with your project.

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this is a really interesting thread. I have some Clara Frijs scion coming this year.

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Derby,
Clara Frijs is a wise choice to grow for pears and for an interstem for quince and possibly other things. I recently found this website published by the National Clonal Germplasm Repository (usda) on other rootstock compatible pears http://www.ars-grin.gov/cor/catalogs/pyrcompatible.html that can be used as quince interstems. These are interesting scion wood Scion Wood For Sale and click assorted scion wood. Note that the Macedonian Quince listed does not get fire blight according to the website. I’m not sure but would imagine it’s dwarfing.

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Thank you thecityman. Ironically my first grafts I did were on a callery pear the same as you. The wild callery is an excellent rootstock and I still use them among other things today. The wild ones can become a real pest if left to do what they want. There will always be that stubborn pear that wont graft and hopefully this interstem information will become very useful to whoever is attempting it. There is precious little information on the subject available.

Bouncing around a bit here.
I’ve done interstems of OHxF513 on callery… I put the scion and interstem together with W&T in the comfort and well-lit setting of my dining room table, then went out to the orchard and stuck the interstem/scion unit on top of callery seedlings. All took and grew just fine. No waiting. Just do it all at one time.

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When possible I make both grafts at the same time as you do. My success rate is almost as good as the single graft. The longer interstems 14-16" fail rate is a little higher. Bill

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I usually put in an 8-10" piece of OHxF513 for my interstem.

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I’m just curios @Lucky_P @Auburn why do you use so much interstem? Why not 2-3 inches?

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So if I put an interstem of ohxf 87 on a seedling pear the tree then would grow to the size of a pear that was on ohxf 87 rootstock?

The interstems are dwarf types and think that the longer ones offer more dwarfing. Not sure if this is correct but I think as you approach 14-16" you get close to the full dwarf effect as if you had used only the dwarf root. Time will tell if I’m correct.

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Derby,
You might look at this discussion again Wild callery pear rootstocks - #10 by Derby42. The idea with these seedlings is they are disease resistant and prolific but produce pears the size of peas as your aware. The seedlings may not be compatible with every variety of pear but other rootstocks such as OHxF87 are much more compatible. Since OHxF87 and others are more compatible than the wild callery pear but still compatible typically with callery they make a nice bridge for callery with a variety such as Bartlett. So you have callery roots and stem , then a piece of OhxF87 grafted on callery , then Bartlett grafted on ohx87 as an example. You can use that same technique with many pears that are not compatible with each other. As an example to clarify interstems take winter banana apple. The winter banana apple is so compatible with other trees it can actually be grafted on pears with great success. The idea of using winter banana apple is not for pears though it is to graft two incompatible apples to each other. If you have the time to read the technical answer there is more available here http://www.hort.cornell.edu/expo/proceedings/2015/tree-fruit/Understanding%20graft%20incompatibility[1].pdf

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I understand now so you might use ohxf333. Typically 6 inches is ok for dwarfing most rootstock. That makes perfect sense to me now. You are doing something similar to what they do with quince http://horticulture.oregonstate.edu/system/files/ond080101.pdf

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This study demonstrates some pears effect on rootstock and scion. Note the Beurre Hardy though useful for compatability is not useful for dwarfing. This study is interesting American Pomological Society - Journal Volume 54 Number 4 A Multi-site Pear-interstem Trial in the Netherlands and Belgium

I have no idea whether OHxF513 will or can have any dwarfing effect whatsoever… it’s just what I had on hand… 513 is compatible with almost all European and Asian cultivars, and Asians on 513 seem not to experience ‘Asian pear decline’ several years out.
I did the interstem grafts… just to see if they’d work… and to see if they’d do much of anything… I don’t expect much dwarfing, as cultivars on 513 itself are generally about 75% of standard size.

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