Apple summer pruning is tricky on vigorous, free-standing trees. The leaves that most efficiently serve fruit are located within 8" of said fruit, but a month of heavy shade can destroy such leaves’ ability to photosynthesize- more or less permanently. Responsibility to feed fruit then shifts to better lit leaves further out in the canopy, so by August, in my northeastern climate, late summer pruning risks apple quality unless done judiciously.
June pruning of vigorous uprights should improve fruit quality and reduce biennial cropping, but August pruning can theoretically have a negative result on both counts. July pruning would tend to be a wash as far as brix levels and annual cropping but helps reduce fungal pressure.
June pruning may have to be followed by a second summer pruning in August, however, depending on how open the tree remains to light on those essential leaves. A hobbyist can do what a commercial grower cannot afford- commercial growers mostly grow non-vigorous apple bushes these days, which pretty much eliminates any benefit from summer pruning.
@Alan, I’ve often wondered what’s the most efficient amount of wood or leaves to retain when pruning new long shoots with a growing apple at the base. On a mature tree I usually just prune off all new shoots devoid of fruit and leave ones with fruit alone, but this can result in watersprout-like shoots several feet long at harvest time. Is there any advantage for the fruit if you leave more than 8", and does the same rule apply to more horizontal fruit-bearing shoots?
Thanks
Trees I need bigger in my orchard are usually minimally pruned based on the guidelines in the article I wrote about pruning by numbers in the guides category here.
Your question seems to be about dormant pruning and the fact that water sprouts always return in free standing trees, usually creating excessive shade over fruiting wood by late spring. On bearing trees you may be describing pruning out next years potential crop if you mean that you are eliminating all one-year shoots, aka pencils. That is, if the variety you are pruning tends to bear most of its fruit on the 2 year old wood behind one year old shoots (same “twig”). Trees managed and prone to bearing most of the crop on these shoots require a rotation where about an equal amount of one-year shoots are retained as the 2nd year fruit bearing ones. Usually you leave the 1 year wood on these 2-year shoots to feed the fruit, removing the entire shoot the following dormant pruning. Standard procedure during dormant pruning is to remove the most vigorous annual shoots and leave the less vigorous ones, but there’s always a certain amount of improvisation based on what trees give you. That improvisation cannot be learned by reading text- it comes from reading trees and remembering some of what you’ve read.
The easiest time to read a tree is when flower buds become visible. The tree will not be adversely affected by delaying pruning until this time- at least in my experience. I don’t live where fire blight tends to be lethal and I’m not sure how delayed dormant pruning influences that disease.
This topic is not about dormant pruning, but about pruning during the growing season.
Some day when I’m spending less time managing orchards I hope to write a book that includes photos to help explain the whole process of pruning. A video would also help.
Yes, this is fine tuning I’ve only been able to do with the help of AI. There are no up-to-date books on these fine points about apple tree pruning that I know of. Almost all research pertains to commercial production where this kind of fine tuning is cost prohibitive. If you have any commercial orchards nearby with free-standing apple trees and not dwarfs, you may notice that trees are pruned extremely open in an effort to assure that spur leaves continue to get at least adequate light through summer without additional pruning. Hobbyists can do better.
Alan, no, I’m discussing growing season pruning. I’ve already done my first round of removing unproductive new growth, and I’m thinking about shortening the new shoots with growing apples on them. I prune all of my fruit trees primarily during the growing season.
Those tend to be the shoots I leave- I rarely do any stub cutting during the growing season if I’m not trying to develop secondary wood of something with a stretch of “blind wood”. I suppose some varieties of apples can be coaxed to produce spurs by cutting back shoots 2 or 3 times during the growing season, but that’s mostly used for espaliers.
I cut back waterspouts and root suckers only. Cutting back vigorous growing branches with fruit seems to me waisting energy of the tree and promoting more vegetative growth vs setting of fruit buds for next year.
I was looking for some details on spring apple pruning and AI gave my this recommendation: June 25 to July 15 in NY. Don’t know how it picked that exact range for NY. It was part of a discussion of the negative effect on fruit quality from lost photosynthesis.
@folkert
You are mostly correct. June is a good time to remove suckers and newer crossing branches.
The “energy” for fruit production is dependent on root processes, especially during above-ground dormancy. In turn, these specifically depend on availability of potash and other minors in the soil before Fall. If soil acidity is not an issue, then a modest application of Sul-Po-Mag under the edge of the canopy will ensure adequate potash. Follow application directions on the product – excess potash can be detrimental.
As you know, AI is only as good as the questions it is asked. Copy and paste my statement about pruning and let AI work from that. What I’m writing, AI is not going to easily find because the implications of research on this subject have not been put together in a single research paper.
Nevertheless, up here, that isn’t a bad time to schedule summer pruning- if you didn’t do it in June. If you only plan one growing season prune, that could be the best time.
You have me scratching my head. Please explain your meaning. The energy for fruit production comes from nearby leaves, literally. All life in the tree depends on root processes but just as much on what goes on above ground. You know this, of course, which is why your statement is confusing to me.
I don’t agree with you advice on K at all, because you shouldn’t be adding potash to apple trees unless you know they need it. Excess potash interferes with a absorption of calcium and causes fruit rots- this I have seen. I have never had an apple show signs of potash deficiency.
Of course the trees I install are originally done so with a 5 cubic ft layer of shredded wood mulch over same of compost, usually with woodchips as a big part of their recipes. However I manage a lot of big old apple trees that never benefitted from that high K breakfast.
I wouldn’t add potash unless a soil test at least demonstrated an apparent deficiency, even it the tree didn’t.
I was thinking about energy from the sun. You need leaves, with buildup chlorophyll, which contains a lot of nitrogen. In the fall, the nitrogen from the leaves gets reabsorbed into wood and roots for next years growth, before the leaves fall. In my mind, summer pruning is like cutting out solar panels, arguing that the tree has installed too much capacity. Maybe in some cases. Where excessive growth is causing shading and or impaired air circulation. But you can also cause this situation by excessive pruning, driving the tree into a vegetative response. Just my two cents.
So, you don’t follow your own 8* rule for new fruit-bearing shoots. Is the new growth beyond 8* contributing to the quality of the ripe apple? I’m not trying to get more blossoms; all of my apple trees produce exessive fruit that needs to be thinned. And most of these shoots will be completely removed after harvest.
Rule? It isn’t a rule beyond that being the distance of leaves that tend to serve fruit. I remove wood that blocks too much light from those 8" and not shoots that extend from those leaves. Perhaps Richard’s comments on roots pertains to what happens if you have more root serving fewer branches. The fruit on those branches might suffer a reduction in brix if they have access to too much water.
The point about leaves within 8" of fruit being the most efficient is something I hadn’t thought about explicitly before, but it makes sense of why heavy summer pruning can hurt fruit quality even when it looks like you’re just tidying up. I’ve been more conservative with summer cuts since reading about this — mostly just removing obvious water sprouts and leaving anything near developing fruit alone until after harvest.
I think from your older posts i picked up the thought that solstices were the best pruning times, at least summer solstice, and to wait until close to that day to do my “pruning for crop”, then winter solstice “pruning for shape”.
i had to do early pruning this week on a plum that is feral, i skipped on height pruning in winter and it was getting whipped a lot more than i liked by the wind. beating up a fence etc. but my apples i will wait again as I’ve learned.
my questions from your guide are all about how to clean out old wood on things that want to grow on that 2 years wood. getting better at selectively pruning for that wood without wrecking the overall structure of the tree.
if you wrote a book and had a human editor i would buy it and read it.
Well, since I didn’t get an aswer to my question of how much, if at all, and when to shorten a vertical, bearing apple shoot, I resorted to asking Gemini AI. Its answers made sense; so, I will apply them this year and note the effects.
Basically, the answer is that fruit development will be enhanced by shortening each shoot to the bottom 3 to 5 leaves above the basal leaf cluster, because leaving the shoot to elongate will direct the tree’s resources to the growing tip (due to apical dominance effects) instead of to the apple.
The timing of the cutting for fall-bearing apples is from mid-July through August, because earlier cutting, like mid-June, will just result in stimulating more growth in the remaining part of the shoot and defeat the purpose of the cut. For early apples like Yellow Transparent, the cutting should be done 3 to 4 weeks before expected ripening, when the lower part of the shoot is hardening and sprouting is already inhibited.
Once again, AI requires direction. What you got was the traditional Lorette method of maintaining espalier trees. The cuts made that late do not favor flower production beyond sustaining what already started in spring, the crucial season for the determination for the development of next year’s flowers. That is why fruit thinning is done at that time to help discourage biennial bearing. The Lorette timing is about controlling size- not crops and it is not a researched based system in the first place, especially for vigorous free standing trees.
Ask Gemini to provide research that supports the efficacy of the Lorette system to force trees into creating more fruiting spurs. Modern research seems not to have endorsed the method for this purpose.
When I stub cut small wood it is usually into 2nd year wood, removing the entire one year growth. This is most often useful when pruning gangly growth pear trees, but I sometime do such cuts in apples when I see flowers buds on the 2-year wood but want to keep upper tiers from excessively shading lower branches. Such cuts don’t tend to inspire the same vegetative response as stub cutting one-year growth.
My business began taking root when I was hired by a couple with about 50 big old apple trees that had stopped bearing fruit because Sav-a-Tree workers had cut the annual uprights to stubs on subsequent years, the 2nd into the hydra heads produced by the cuts made the first year, essentially creating an vegetative umbrella over the trees and vastly reducing their ability to produce fruit.
I immediately brought the trees back into productivity by removing the entire vegetative umbrellas from the trees. Fortunately, the spur wood hadn’t been excessively removed as has been the case in many subsequent orchards I’ve been called on to manage.