If you’re a fruit geek like me, you sometimes wonder what kind of fruit trees you can successfully manage to graft together. Several years ago, I started wondering that question about two excellent fruits in the Ebenaceae plant family: American persimmon (Diospyros virginiana) and its cousin chocolate pudding fruit, also called black sapote* (Diospyros nigra).
These trees and their fruits are very different in appearance and flavor. Chocolate pudding fruit is native to Mexico, has stiff, evergreen leaves, and requires tropical and and near-tropical climates. Its fruits are large, with a sweet flavor that people describe as resembling chocolate pudding or chocolate mousse.
American persimmon is native to much of the eastern third of the continental US, where it grows over a wide range of climates, from subtropical Florida to cold-winter areas of Indiana. The trees are deciduous, and produce small fruits which taste a bit like a soft, squishy date.
In early 2015, I decided to see if these two members of genus Diospyros could be grafted onto each other. Partly I wanted to see if using the super cold hardy American persimmon as rootstock could impart some additional frost tolerance onto the tropical chocolate pudding fruit. But also I was just curious if these related fruit species, which are so different in appearance, could be fused into one tree.
I had never heard of anyone grafting these species, and I expected it might be a slow and difficult process for them to join their tissues together. So to test the combo, I used an approach graft, which can be helpful in difficult graft combinations. I had a seedling chocolate pudding fruit growing in a pot, and around it I placed several seedling American persimmon seedling growing in pots, and I sliced a strip of bark and cambium off branches of each tree species, and bound those cut surfaces together.
After several weeks, the trees appeared to have grown together at the junctions, so I cut the connections to the chocolate pudding fruit parent tree in step-wise fashion, first girdling the branch, then cutting through more and more of the remaining wood, until I’d cut entirely through the last bit of tissue connecting the scions to their parent tree. All of the grafts handled this process successfully, and as a result I had a number of potted chocolate pudding fruits grafted successfully onto American persimmon.
I have since moved some of the seedlings into larger pots, and they have continued to grow well up to the size of the pot they’re in, with little to no sign of graft incompatibility as of 2019, four years later at the time of this writing.
One possibility I had wondered about was whether the cold hardy rootstock would impart additional frost tolerance into the chocolate pudding fruit scion. I found out by accident when I accidentally left one of the potted trees out over a frosty night that this does not appear to be the case – the tree suffered extensive frost damage, although it did not lose its graft. To properly test if there is any small difference in frost tolerance produced by this graft, it would be necessary to plant out a number of chocolate pudding fruits, some on their own roots and some grafted onto American persimmon, all exposed to frost identically, and observe how much damage both get.
Another possibility is that American persimmon could potentially function as a dwarfing rootstock for chocolate pudding fruit, especially if you use a smaller-growing growing clone of American persimmon. My trees growing in their pots have adopted a fairly sprawling growth habit. I don’t know if this is an effect of the grafting process, or because I used side branches of the chocolate pudding fruit, which have retained their side-ways growth habit.
Since this was just a random “can it work?” project which I hadn’t really expected to succeed, I used a seedling black sapote plant which I happened to have. So the grafted trees have juvenile wood, and have not flowered. I haven’t bothered planting them in the ground, because with their juvenile wood, these might take quite a while to start flowering and fruiting. I should try it again using scions cut from a mature, fruiting chocolate pudding tree, which could make trees that would start producing fruit potentially in just a few years after grafting.
Another possible use of this graft is if there are soil conditions which American persimmon can handle, but which chocolate pudding fruits have trouble with. (I’ve seen American persimmon thriving in flooded soil conditions – I don’t know how well Diospyros nigra handles flooding.)
I told fellow tropical fruit enthusiast Paul Zmoda about this successful graft, and he successfully replicated it, doing a cleft graft in August 2016. His grafts healed rapidly, and he has at least one tree he’s planted out in the ground at his location near Tampa, FL. He reports that as of August 2019, his three-year-old tree has flowered but not set any fruit yet. Unlike my plants produced with this graft, his tree has an upright growth habit.
I have not tried doing the reverse graft – American persimmon on chocolate pudding fruit. I’m not sure if that combination would have any use, but maybe it could allow American persimmon to grow in more tropical conditions than it can on its own roots.
Done either way, this graft combination may or may not have any practical use. But if anyone wants to experiment with possible uses, these two tree species seem to graft onto each other quite easily.
*Note: I use the name “chocolate pudding fruit” preferentially over “black sapote” because of the inevitable confusion generated by the “sapote” names for various unrelated fruits.