I just got a hold of some nice heartnut scionwood. I have several nice sized black walnuts seedlings that Id like to top-work over. This will be my first foray into grafting walnuts, which I understand can be tricky. I was told that apart from callus temps being at the upper end of normal weather here, another big hangup is bleeding and resultant flooding of the graft union. We’ve had over 15 inches of rain in the last month. We just got nearly 2” more in the last couple of days. I was told this amount of precipitation will pretty much spoil any hope of a successful graft. Im wondering what everyone’s experience is and whether anyone has any special techniques to mitigate against this. Any info or advise welcome.
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First and foremost, walnut grafts are different from most other trees because the most successful scion is the large terminal bud. The second thing is that an inlay side graft is more successful than most other grafts because it avoids bleeding. So pick your scion carefully and trim it with a 2 to 3 inch slant cut similar to what you would make for a whip & tongue graft. On the back of the scion, make a similar cut about 3/4 inch long so that the cambium is exposed on both sides. Now hold the scion up to the bark or a 1 to 2.5 inch diameter walnut seedling. The graft should be about a foot high, no more than 2 feet above the ground. Using a sharp sheep foot knife, cut on each side of the scion through the bark. Put the scion aside and make a downward slanting cut across the two lines you just made at the very top of the cuts. The purpose of the slant cut through the bark is to allow the scion to set in the groove tightly. Now use your blade to pull the bark flap out from the trunk about an inch. Push the scion into the groove until it is entirely covered by the bark flap. Cut the bark flap off so it just covers the 3/4 inch cut on the back of the scion. Use two wire nails no more than an inch long to nail the scion to the trunk. One nail should be near the top of the graft cuts, the other nail goes through the bark flap and into the wedge part of the scion. Don’t nail too tight, just enough for a snug fit. Cover with beeswax or other graft sealant.
Aftercare is crucial. Exactly 10 days after the graft is made, cut the top of the tree off about 2 feet above the graft. The stub will help prevent bird damage and will give a support to tie the growing scion so it does not get blown out by high wind.
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great summary. ill take it to heart and out to the field. i already favor a side graft and so was planning some version of that. Given the caliper of my rootstock (~1 1/2” - 2”) Ill probably wind up with a bark or veneer graft of some kind. Your method sounds like what i would call a side veneer graft. I guess with a bark flap, it would be more of an inlay graft though. its my go-to graft for most things that are tricky in any way. i like how much flexibility it gives you in working with different calipers too. from your response, it sounds like you aren’t overly concerned with bleeding? the guy who gave me the wood was pretty emphatic about what an issue it was. glad to hear more about your experience. what do you shoot for in terms of weather, and what is your take on average?
Ideally you would have rain a couple of days before grafting and again within a week after grafting. Bleeding is not a problem until the top of the tree is cut off at the 10 day mark.
My best average with walnut is 90%. My worst was about 50% when I grafted during a dry spell. Takeaway, graft walnuts when the bark is slipping and there has been rain recently.
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interesting. the fellow who gave me the wood and the advise cuts the whole top off and does a bark graft where he’d made the cut. I suggested to him that side grafting lower might be a better approach, so glad to hear that its been tried and true for you.
Im scratching my head a bit about what bleeding is, what its driven by, and how to mitigate it. For tricky grafts, I always think sap flow PAST the union is a good thing. I suppose that if you don’t sever the xylem- and one wouldnt with a bark graft on an intact stem- there shouldnt really be an outlet for sap.
He is cutting the top off of the tree, then grafting. Walnuts and pecans will bleed severely under those conditions, particularly just after rain.
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This spring was my first time grafting walnuts. My black walnut scionwood was from @Fusion_power. The quality of scions was excellent. I had really good results with a side graft. I’ll have to try the inlay side graft next time.
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@SteadyStan, with results like that, you are doing fantastic. That is exactly the graft I would have done on smaller stock. The inlay side graft works best on stock from 1 to 2.5 inches diameter. Your side graft is working great on smaller stock from 1/2 to 1 inch diameter. If I read your tags right, you have Thomas, Cranz, Neel #1, and Sparrow.
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Thank you! You read the tags correctly. I was 4 for 4 with the grafts I made mid May. I did a few more grafts mid June, so we’ll see how they turn out.
Oh, that makes sense regarding when to use the inlay side graft.
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Hi Darrel,
How many years does it normally take to have a side graft mature so it’s strong enough to resist wind loads without being supported? Do you usually prune off the top once you think the graft is strong enough?
Dennis
Kent, wa
id think youd want to prune it soon after to force that scion. Darrel was saying to cut the whole top at 10 days if I understood him correctly.
He was advocating leaving a couple of ft. of trunk in place to serve as a support for scion growth (with appropriate lashing) and bird perch. This is my preferred method for mulberries and persimmons, so Im glad to hear it works well for @Fusion_power on Juglans
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I had a Neel #1 graft blown out by high winds when it was in the 3rd growing season from graft. It was 100 mph or more wind that leaned several older walnut trees over to the ground. I had to use a tractor to pull them back vertical and lash them in place until the wood fiber hardened enough to support the trees. My rule of thumb is that any kind of bark graft should be supported for at least 3 years.
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Geez!
It was associated with a tornado that passed by a few miles away.
Anyone tried using the girdling method for the bleeding? Saw some video of people using it.
A very old grafting text from the early 1900’s recommended using a drill to bore a hole about 1/4 inch diameter through the rootstock below the graft. The idea was to force bleeding at the hole instead of at the graft higher in the tree. I don’t bore holes and I don’t girdle trees. Take care of it the simple way, do an inlay side graft or a side slice graft like SteadyStan. There is no bleeding and the leftover stub is a handy support for the growing scion.
well, I dont know about the no bleeding part, but Ill see how it shakes out. I did my first 3 heartnut grafts- all ‘Imshu’- on a good sized black walnut seedling. Its been raining like crazy here- probably around 18” and counting since June 1. I did 3 bark inlay grafts, and when I made my first cut I could see that bleeding was going to be an issue. We have good callusing temps coming up, the first of the year really, so I decided Id better forge ahead.
I decided to attempt to mitigate bleeding by partial ringing. I made a notch cut through the bark a couple of inches below each graft. This is the opposite of how youd locate a bark ring if you were trying to encourage vigor on a bud or limb, but it makes sense in that the water pressure is being intercepted below the graft union, hopefully creating a localized drop in pressure at the graft.
The scionwood looked nice enough. It didnt include the apical bud. There seem to be some catkin buds. I can’t differentiate them from secondary buds as of yet. I assume I can rub out catkin growth without issue should the need arise.
I sealed scions with parafilm and wrapped the graftd in parafilm too. This proved to be a poor fit, because the trunks were wet with dew and so the parafilm had trouble adhering to itself. It also used an ungodly amount since the trunk caliper is 2” plus. I chuckled while doing this, thinking of the videos i watched about “Texas inlay” grafting pecans, where duct tape seems to be the preferred grafting tape. Lastly, I wrapped the whole works tightly with cloth friction tape. This layer adhered well, and I was able to detail it so that it is probably weatherproof in an of itself. Im thinking all of this os probably an improvement over duct tape and a bread bag or aluminum foil (as the videos depicted) but the proof is in the pudding, as they say. FWIW, I didnt see any evidence of sap leaking out of the graft after being wrapped.
Fingers crossed. The ground is saturated and will be for some time to come. Hopefully this is not a fools errand. I still have more ‘Imshu’ to graft, plus ‘killdeer’, CT-3, and another one i can’t remember. Ill let you all know how they turn out.
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