Rejuvenation pruningis a pruning technique that Pons mentions in his book. While he is specifically talking about old in ground trees, I don't see how this technique can't be applied to potted or young trees. In fact.. I really think this technique should become a standard practice the following year after rooting. So as an example, you rooted a cutting in January of 2019. Now during dormancy almost a year later, perform the technique. Please note: some discretion must be taken into consideration when dealing with such a young tree.
AscPete has also talked about this in numerous threads:
"The tree can be renewed after several years by pruning back to the main trunk and starting over, or just air layering a large branch, and starting over. Also an additional benefit of this pruning technique is that the fruiting branches can easily be air layered or harvested for new plants or cuttings. There are documents that show scaffold branch renewal by removing the established scaffolds / cordons and retraining new scaffolds / cordons from fruiting branches located close to the main trunk. Also as the tree gets older and more established the node spacing will actually decrease due to the available nutrients and quantity of actual new fruiting branches. You could also air layer new plants from the fruiting branches and train them."
My thoughts & experience:
I was pretty skeptical when Pete first started posting about this renewal process years ago. Simply due to the fact that you're essentially cutting your tree all the way back to almost nothing, but this method can be extremely helpful for trees that are stagnant growers, have heavy FMV, or low productivity. It can be helpful for a whole host of problems. I really see it as a cure all to get the variety performing the way the genetics say it should. That sounds pretty extreme, doesn't it? The elixir of life for fig trees?
As we all know when our trees get killed to the base, they resprout very vigorously and much healthier than before. A great example is Herman2's Ischia Black (UCD). This variety is notorious for having severe FMV and was brought back from the dead when Herman2's tree was killed to the soil line by the cold (a form of rejuvenation pruning). The next year it resprouted and became much healthier. Today most Ischia Black (UCD) in circulation comes from Herman2's tree. Additionally, the question of why specific trees just never do well has always baffled us. You could have 10 copies of the same variety and 1 or 2 may severely under perform compared to the others. I think it's a reasonable speculation that if every tree is off on the right foot with a healthy vigorous trunk as its base, you're giving your tree the best chance to perform the way it was meant to. It would save us time in the long run and make our observations more accurate. For example, I am confident that my Hative d'Argentile on its own roots would perform a lot better with this reset switch. Maybe a tree that was dropping would stop or start to slowly hold? Maybe I wouldn't have to cull a specific variety for "X" reason?
I performed rejuvenation pruning on my potted Planera tree that's in its 3rd year. For three years, it barely grew and put out a shockingly low amount of fruit. If I asked anyone else how their Planera was doing, it was the total opposite experience I was having. After chopping it all the way back to the base in June, it resprouted with a new healthy vigorous shoot. Growth and healthy leaves that I haven't seen from this variety. I believe that my tree will act like Planera should from this point onwards.
In my opinion this method definitely beats starting over completely. A lot of people give up on a tree. Either it's too old in its pot or it just doesn't perform correctly. A lot of us have already seen the results of air layering the top of our trees. That's kind of like starting over though. Maybe that's necessary in particular situations, but if we could just cut the tree back to healthy wood, I think we'll see the results we were hoping for.