I had previously read about pruning vertical shoots to force them to become fruit spurs. what is the timing and where do you cut? How successful is this?
I was told about it by C. Lee Calhoun, who planted the Southern Heritage orchard at Horne Creek Farm in NC. He pinches them back to three leaves as soon as they develop, and then has to do it a couple more times in the season as it tries to re-grow. They have a lot of trees on single cordon espalier there and this is how they control branching.
CCKW, this is a technique traditionally used for espaliers and in most situations shouldn't be needed to bring fruit trees into productivity. How are you planning to use it?
I could see it being useful in any situation where you want productivity in less space that what the tree is predisposed to require before settling down to bearing fruit.
Harvestman, my honeycrisp is 5yo and put on apples this year, but only 5. I have the tree in good shape and health I want to be thinning on this tree next year rather then counting the crop on my fingers.
My 5yo Harelson and 4yo Fireside both needed thinned this year.
I learned it here for my McIntosh. It is an espalier and the constant pruning would turn the spurs into branches.
For this tree it was late summer right about the time the fruit is ready (late August).
I started holding off pruning until that time and it got the tree back into bearing.
If your tree is first bearing I'd expect it to start going on its own now that it's started.
This is not something that accelerates bearing accept in the situation I mentioned. Your tree already has spurs- maybe they aren't getting enough light and the tree needs opening up. If leaves on small wood don't get enough light they won't fruit. More thinning cuts in the dormant season is the more common prescription. Is the tree open enough after winter pruning that you can throw your cat through it?
You can also remove uprights attached to big wood in mid-spring to assure the smaller wood gets adequate light. Then remove them again in mid-summer.
How a tree responds to repetitive pruning of smaller uprights is somewhat dependent on the variety. Macintosh bears its best flowers on the 2nd-year wood of moderately vigorous shoots so repetitive pruning would probably interfere with its ability to flower.
I did open it up pretty will this past spring. But based on your advice, just got back in from getting rid of water sprouts that were blocking light. Thrown firmly, a cat would now clear to the other side, especially if were just a yearling.
The idea of early removal of annual shoots that don't serve the spurs is based on the fact that the spurs determine whether to produce flowers for next year's fruit mostly within a month of petal fall- based on energy reserves in the spurs themselves (exclusively acquired from spur leaves, at that point). This is why fruit thinning needs to be finished by then to help assure annual bearing.
Even the smaller shoots near spurwood provide no energy for the spurs until mid-summer, when they've stopped growing (much). By then they help improve the quality of the fruit but have little influence on next years flowers.
An adequate amount of annual shoots should be saved to serve the spurs from mid-summer on. That is why I suggested early removal of only shoots attached to "big wood".
Removing the big wood shoots to better serve spur wood is not something directly supported by actual research, it is just a personal hunch, by the way- it is only logical.
In home orchards, shade often comes from more than the tree itself- buildings or nearby forest trees for instance. Home orchard trees often need to be pruned even more open than those in commercial orchards for this reason.