I also agree that their 3-5 year estimate to produce nuts is too optimistic. I have bought 3-gallon trees from Walmart that were producing nuts when I bought them. Even after a couple of years in the ground they have not produced another nut. I am okay with that as I view them as a long-term investment. I would rather a larger payoff later than a short-term gain now. I want them to put energy into developing roots and not producing a few nuts each year that will not be more than a quick snack for wildlife. I have seen so many people comment on how their 5-year-old trees aren't producing. They bought into the hype of getting tons of nuts quickly and it just isn't going to happen in most cases.
Years ago, I planted some bare root Tigertooth Jujube trees as an experiment based on an article David Osborn wrote for Quality Whitetails. That variety is supposed to be self-fruitful. The trees grew well (except for one that got some gly drift). They got bigger and bigger and older and older, but still no fruit. I was beginning to suspect that they were not really self-fruitful or the Jujube trees I was sold were actually another variety that required a different variety as a pollinator.
Meanwhile, I was experimenting with propagation. I took some root cuttings from these Jujube trees, hit them with rooting hormone and put them in some sand. I gave up on them after a couple months, but one day, quite a bit later, I noticed something growing out of that sand. First one, then another, and so on. I got several clones of one of the trees. Most Jujube are grafted onto wild jujube root stock, but these Tigertooth were grown on their own roots, so these were clones of the tree I took the root cuttings from. As the grew, I transplanted them to 1 gal Rootbuilder II containers. By that fall, I got a couple tigertooth fruit on these clones that were less than a year old, yet the 15' parent tree had not produced any fruit.
I emailed both David Osborn and eventually got connected with a university professor who was an expert on jujube. The professor judged that my trees in the field were not mature enough to produce fruit. They were still in a vegetative growth state. He believed that the container constricting the root system caused the tree to move from a vegetative state to a fruit production state. He said this is not unique to jujube and happens to other trees grown in containers. He suggested that as soon as I planted the young clone in the field, it would revert to a vegetative state and stop producing fruit.
He was absolutely correct on all accounts. Several years later, my jujube trees in the field started producing and production got heavier each year. When the clone was planted in the field, I stopped producing fruit.
I believe when you see nuts on the walmart Dunstan trees, it is exactly this phenomenon and it is what you experienced.
I completely agree, that adding mast trees is a long term project and there is no real short-cuts. There are things we can do to maximize chances of success, but it is all pretty long term. My quickest production comes from native persimmon trees that I cut down and bark graft with female scions from mature trees. It is not uncommon for them to produce persimmons in the third leaf, but it still takes quite a few more years before the production becomes substantial.
Thanks,
Jack