I am in zone 5-5B . What time of year for field grafting . I know they need more heat to callous . Thinking early June to get enough heat . I realize now I have been grafting too early .
That’s exactly, correct. We were going to do a walnut grafting demonstration Jerry at Red Fern Farm on walnuts and had our date for the last week of May. It was cancelled, ultimately. So, late-late May and until mid-June is the sweet spot.
Since you’re in IL and right near me, you couldn’t get better information than this.
NW IL zone 5b
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Thank you . I saw a video on bench grafting walnut and they put theirs in totes with damp sawdust and held them at 28-30 C for three weeks while they callus .
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I don’t have advice but using the hot callus system on the Guides section of the group with black walnut rootstock being dormant and grafting dormant scions, they bled. I talked to Cliff England about it and he said they bleed when dormant on pipes. He uses barely moist compost to contain his bareroot walnut trees on a hot pipe (he said something like “dry compost”) and said that helps.
Now the same callus pipe I use a guy over in Europe grafts Juglans regia on regia and didn’t have any bleeding issues. Different species, different result.
I just don’t graft them. I did them once and they all bled (75-80 trees) and I got (2) survivors.
You can’t sell them anywhere.
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I just discovered this interesting procedure for bench grafting walnut, basically using a root graft:
Black walnut bench-grafting procedure reduces stock suckering.pdf (1.9 MB)
Anyone try anything like this?
Some takeaways:
- Reduces need for post-graft removal of rootstock shoots
- Apparently a cleft graft works fine in this situation
- Milk carton makes a good impromptu pot then turns into wind shield at planting
- “Discarded” stem portion of rootstock will re-root (I’m assuming this is because some of the stem is from below the root collar)
The one thing I’m not understanding is why a mist system would be required for this method. Is that just to slow down scion growth until the graft has time to heal?
Misting grafts is almost always to prevent the scion desiccating. Usually the roots can take up enough water to contribute callus. The scion does not have water unless it is misted on the stem.
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That’s what I thought. What confuses me is that the author specifies a wax dip (I would probably use parafilm) but also says misting is necessary. I know this is an older publication, but is this a “belt and suspenders” situation, or are black walnut extra prone to drying out?
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The cut off tip is being dipped/painted with wax but not the scion and then the union are covered in wax but not the roots.
It is odd to me also, Jay. If the roots and the union are inside the milk cartons with perlite/other that is kept moist for the callousing and for the roots, then I wouldn’t understand why the wax is there…
Another system commonly used is a wooden frame on the ground with heat lines running across the bottom and sand fills it. The sand is kept moist and the grafts are tucked into it and the box/large frame is covered with poly. The poly is opened periodically to keep it from becoming to moist inside.
I’ve seen this inside hoophouses where during winter they’re grafting at picnic tables inside and tucking the grafts away to callous - this way. Unions are always buried, also.
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This person is making it really difficult. A plastic cover over their milk cartons would achieve the same thing as a mist system. Or, waxing the whole thing minus the roots.
The whole thing is a bit suspenders heavy!
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