Black mulberry (M. nigra) can be air-layered. I have seen pictures (below). Does anyone have enough experience with the long term survival and longevity of an air-layered black mulberry?
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Since nearly all of Morus nigras purchased here in the US are grafted, I asked a Belgium nursery owner about your question…this was his reply:
"About grafted versus own rooted Morus nigra:
Here all morus nigra are own rooted. I have a colleague nursery men who specializes particularly in propagating Morus nigra. Semi lignified cuttings are taken in July and rooted under mist. He has a very high success rate in rooting these cuttings so there is no need for grafting… The main difference between grafting and rooting is that the graft union with Morus alba will form a burl after many years and the tree will not live as long. I have both a grafted and own rooted Morus nigra in my garden and I can see no difference in vigor. Generally speaking Morus nigra is preferably propagated on its own roots instead of grafting onto Morus alba.
Maybe grafting onto the vigorously growing Morus latifolia might transfer some of that vigor onto Morus nigra but I have no experience with this."
At any rate, I have decided to put your question into a test and have started an air layer on my Morus nigra. I have wondered whether grafted or non-grafted has any disease advantage for us folks here in the southeast.
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Please do keep us posted!!! Thanks
Looks like we’re due for an update. 
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Well I’m glad you posted as I missed this thread. I’m going to do an air layer this spring now that I read this. I have air layered a few different plants.
I would love to know if I need to girdle the branch?
I have one of the hardest Nigras ever found. The mother tree was growing in zone 6b in ground. No other nigras anywhere in sight. Since I know of only 2 examples of a Tsarigradska mulberry seedling from Vratsa Bulgaria, and I have both, I have been protecting the plant. I will air layer another to plant in ground in zone 6a
The mother tree was infected with a fungi, it produced both male and female flowers. I have 2 seedlings from the tree. All the genetics are from this lone hardy Morus nigra. One is thriving in a container, the other has barely grown in 4 years.
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That’s amazing! Also, does it regularly set seed? If it fails to layer, its own seedlings would probably make the best rootstock for long lived grafts.
No, a female tree only produces male flowers (catkins) if under stress. Unless it’s a male tree, which will regularly produce pollen. The trees I have could be male? If so I will buy a nigra female and go from there. It takes about 6 to 8 years for seedlings to flower. My tree is 5th or 6th leaf. I should know this year or next.
Here is a photo from almost 3 years ago. In May of 2019. I don’t have any recent photos. It has the typical black buds of a nigra. No doubt as to what it is.
The tree has started to throw spade leaves now. I love the fig leaf shape though!
I found a photo from last year in August 2021.
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To give an update…
The airlayer rooted just fine and had a strong root system. However, it grew a little and seemed to be just fine but never returned to growth (died) following winter dormancy in my greenhouse that has temperature control and never fell below 32 degrees. Never had a chance to even plant it in the ground.
Perhaps I will try it again this year, in hopes it was just an unrelated problem.
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I’ve lost plants overwinter in greenhouse while their counterparts outside the greenhouse survived. Greenhouses add other variables besides temperature control. Primarily they create an environment that can favor some rot pathogens.
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I am not sure I am understanding your question correctly as I didn’t know that air layering is possible without girdling the branch before wrapping the girdled spot in sphagnum moss or coir and plastic wrap.
I have not needed to girdle figs or honeyberries. They will root without girdling. I have air layered figs about 12 times and all were good. I myself like to use potting soil. And I use plastic bottles to hold the soil. I think I will girdle the branch. Why I don’t like to is if the air layer fails you still have to remove the branch. Also you can remove the bark to girdle or you can use wire. Wire slowly girdles the branch.
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