Wednesday, April 25, 2012

My Apple Grafting Experience

I attended a grafting workshop recently, held about 2 hours away at Foggy Ridge Cider (a small but highly acclaimed artisan hard apple cider producer) near the Blue Ridge Parkway. It was taught by several men from the Carrol County Extension Service and some of their Master Gardeners. What an interesting and fun experience!  

I took my camera, but forgot to check if the battery was charged. It wasn't (what a dunce!), so no personal photos from the class, but I found a few photos from Flickr that show some details.

Grapevine Rootstock, Photo from Southern Oregon Wine Institute







The class was limited to 15 participants, and they provided 5 rootstocks for each of us, and a choice of scion wood from about 25 apple varieties. In the photo above, the man is holding grapevine rootstock, but our apple rootstocks looked the same, just smaller diameter. (Scions are dormant twigs with buds taken from the tree you want to grow; it will grow on the rootstock into a genetic duplicate of the original tree, but with the size, vigor, and disease resistance of the chosen rootstock.)

Our class was provided M111 rootstock, which is a semi-dwarf tree size. ("Excellent all-around rootstock for apples. Induces early and heavy bearing. Tolerates wet soil, dry soil, poor soil. Resists woolly apple aphids and collar rot. Trees dwarfed to 85 % of standard.") Semi-dwarf apple trees can be pruned to keep them smaller, like the dwarf apple trees, but they will grow much more fruit than the dwarf rootstock. There are different rootstocks developed for a variety of trees; some are variety specific, and some will accept a graft from a different variety. For example, most (but not all) pears are grafted on quince rootstock.
I had already read a bunch of stuff about grafting, but it's a LOT harder to do the first time than it looks. (That might be because the rootstock they received for our class was a smaller diameter than they preferred, and which they lamented.) There are 2 important things to do. One is to get the cambium layers on at least one side of the mating pieces to line up. Otherwise, the graft will not grow. You have to also cut carefully so the cambium isn't damaged. (The cambium layer is the thin green layer you see if you scratch a bit of the bark off with your fingernail. It is only a couple of cells thick and produces new tissue for growth.) The other important thing is to be sure the buds on the scion are pointing UP from the graft!

a whip-tongue  or whip-cleft graft

Other than the problems due to our small-sized rootstock, grafting is really easy... at least the whip/cleft (shown above), and modified cleft grafting (below) which most of us ended up doing because of the skinny rootstock. The instructors didn't cover other types of grafts like bud grafting, chip grafting, and bridge grafting which is used to repair a damaged tree.

Modified Cleft Graft, sometimes called a "V" graft, photo by ghadjikriacou

My first graft cut was the "whip and tongue cleft", shown in the line drawing (above the Modified Cleft Graft photo). It was not easy with the thin rootstock, and very hard to get the tiny tongue cut and in place, so my other 4 grafts were cut like the Modified Cleft Graft shown just above. Much easier!!
 
I quickly learned my trusty pocket knife won't do the job of cutting grafts! A grafting knife (they had many for us to use) is only beveled and sharpened on one side... and sharp as the devil, so careful handling and cutting is necessary. The blade shape made me think of my grandfather's old shaving razor, which is also beveled and sharpened on only one side (the grafting knives they had were not the folding kind, although folding ones are available, and are safer to carry in your pocket out into the field). 

My grandfather's razor was honed on a leather strap, just as the grafting knives are honed. I still have my grandfather's razor and plan to try it out the next time I have the opportunity to do any grafting, but I'll probably purchase a good folding grafting knife. Here's a short video on How to Sharpen a Grafting Knife.




They also had a couple of fancy tools to make the cuts, but I chose not to use one. I figured I'd best learn with a knife since grafting has been done for centuries without a fancy and possibly expensive tool.

After we got each graft taped tightly to keep the matching cambium layers in contact (we used masking tape, although electrical tape would also work, but NOT duct tape), the graft needs to be waxed. I chose to bring mine home before waxing because I already had wax at home, AND I could drive 2-3 hours home without sticky fingers!



You can buy expensive grafting wax, but they used a toilet bowl wax ring... much cheaper and just as effective. The taped graft area gets covered well with wax, as does the very top of the scion to prevent moisture loss. The instructors said the wax may have to be replenished 2-3 times over the summer. (Probably melts in summer heat.)

These are my grafts, before waxing (what looks like double stems are just shadows on the blanket)

Grafts after waxing

All 5 of my grafts were soaked in water for 2-3 days to awaken dormancy, and then were potted. They will need to stay in pots for a year or so until they get some size, but for the class cost of $15 which included my 5 apple trees to bring home, it was a good deal. (Plus my gas for the trip, but still cheaper than hands-on class lessons, and then buying potted grafted trees + shipping!)

All the scion varieties I selected are vintage apples, and the one I'm most excited to have (hoping especially that my graft on that one takes) is a crabapple developed by Thos. Jefferson, who grew them in abundance for hard cider: the Hewe's Crab, sometimes called the Virginia Crab.

I only wish we'd had a list in advance of the varieties for choice. One I chose is an early bloomer (which I didn't know when we chose our scions) and we usually have late frosts where I live.

These are the varieties I grafted:
Shockley (a North Georgia heirloom, keeps its shape well for pies and preserves) Ashmead's Kernel (highly-valued apple for juicing and hard cider)
Cox's Orange Pippin (classic dessert apple, great for fresh eating, pies and cider)
Arkansas Black (very long-keeping tart apple from Arkansas, thought to be a seedling of Winesap)
Hewe's Crab (produces a delicious cinnamon-flavored cider that is both sugary and pungent. Thos. Jefferson planted his entire north orchard exclusively with this variety)

Did you know melons, eggplants and tomatoes can be grafted on hardy rootstock to reduce diseases and increase yields? (You won't find those plants in garden centers; those are grafted by growers for their own use.) There are a few companies who grow and sell the specific rootstocks for each of them.

I'll have a post on grafting vegetables in a few days.

9 comments:

  1. Fantastic. Grow your own rootstock - http://vimeo.com/album/1630647/video/25814288 and choose your variety from among 4900 malus varieties including 1300 varieties of Malus domestica held in the GRIN collection - http://www.ars-grin.gov/npgs/acc/acc_queries.html

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    Replies
    1. Thanks, Mike. Great resource links!

      I don't have space for more apple trees, but would love to grow my own rootstock and maybe sell a few grafted apple trees.

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  2. How did the grafts do with all of this heat?

    I've been very pleased with how my apple rootstock trench layering has done this year. In a space 3' x 10', I have 6 trees layered with will each produce about 5 rootstocks next spring although I may cut them and pot them up this fall after they have gone dormant. I'll sink the pots into the ground to overwinter them.

    BTW, bud grafting is a far easier technique that doesn't put the rootstock at risk because you only cut the rootstock if the graft takes. If it doesn't, you can pick another spot on the rootstock and bud graft again. You can also bud graft during the summer while things are growing.

    Regards,
    Mike

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  3. Mike, to my dismay, none of them took. Two actually put out tiny leaves from one bud, but then soon died. I don't know why, but I'll try again!

    I'm not sure what you mean about only cutting the rootstock (bud grafting) if the graft takes.

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  4. Darius,

    Could be any number of reasons - scionwood that wasn't properly refrigerated, poor cambium contact which often occurs if you "whittle" the wood and the surface isn't not flat as a result. Timing is pretty important. The rootstock needs to start growing quickly in order to force the scion into bud but the wound also needs to callus over. Did the rootstock survive, ie, did it put out growth below the graft union?

    I had to "park" some scionwood this year because I didn't have enough rootstock to I cleft grafted onto the branches of some wild apples. Only one failed. I also cleft grafted onto rootstock and neither took even though it was a smooth cut and the tape made a good seal.

    When you bud graft, the bud is inserted into a t-shaped cut in the rootstock. After taping, the rootstock is allowed to grow while the bud stays dormant until next year. If graft takes and the bud breaks dormancy next spring, the rootstock is cut a few inches above the graft and the new shoot is tied to the remaining rootstock stub to train it vertically. Eventually, the stub is trimmed. If the graft doesn't take, the rootstock isn't cut and can be used again.

    With bud grafting you also get more grafting material. The rule of thumb is two to three buds are required for successful grafting. With bud grafting, it's possible to use all two or three buds if none is a fruit bud.

    Regards,
    Mike

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  5. Yes, the rootstock but out growth below the union, but I pinched it off. Was that a mistake?

    The instructor inspected each graft I made before we wrapped them, so I assume he knew what he was doing.

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    1. Sorry, typo. The rootstock PUT out growth...

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  6. I suspect that pinching off the growth might have been a mistake. Without photosynthesis, the sun's energy can't be converted. The starch stored in the rootstocks roots over the winter doesn't last long. I'll bet that not only did the grafts not take but the rootstock died as well.

    It would seem to me that keeping the leaf growth below the graft union until the scionwood buds fully leaf out and start growing is probably a good idea.

    Regards,
    Mike

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    Replies
    1. I'm afraid you might be right. sigh. Also, the rootstock was very small in diameter, and even the instructor apologized for it.

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