Rejuvenating Old Fruit Trees
Objective of Rejuvenation Pruning
The main purpose of rejuvenating pruning is to increase the vitality of an older tree, and hence its productivity and fruit quality, while bringing the limbs down once again to a level where the fruit can be picked with an 8 foot ladder.
Another important purpose of rejuvenating pruning is to produce scion wood that can be used to reproduce the variety through grafting or budding onto a young rootstock. Old neglected trees often have little or no young one-year wood that can be use for grafting or budding and the dormant season rejuvenating cuts stimulate the growth of new shoots in the vicinity of the cuts. The reason that cutting off a limb (or cutting back several limbs) in the dormant season causes a flurry of new growth is that before the cuts were made the top and bottom (root system) had come into balance. The root system had just the right amount of nutrients to feed to top. When the top is reduced in size through some cutting, then the root system pumps up the same amount of nutrients which get expressed in greater new growth of new one-year wood that can be used in grafting and budding.
Print Resources for Rejuvenation Pruning
Outstanding PDF from Bob Leaver (East of England Apples and Orchards Project). Review it first.
http://www.ancienttreeforum.co.uk/wp-content/uploads/2015/03/Restoring-Fruit-Trees.pdf
Excellent, well illustrated discussion on Fedco website.
https://www.fedcoseeds.com/trees/renovating.htm
Excellent, well illustrated discussion on Penn State Extension website.
https://extension.psu.edu/home-gardening-pruning-to-renovate-old-fruit-trees
Recommendation on whether to rejuvenate and how to steps to rejuvenate from Oregon State Extension.
https://extension.oregonstate.edu/gardening/berries-fruit/restore-those-old-fruit-trees
Recommendations from Royal Horticulture Society (UK)
https://www.rhs.org.uk/advice/profile?pid=279
Recommendations from Michigan State University Extension
https://www.canr.msu.edu/news/rejuvenating_old_fruit_trees
Video Resources for Rejuvenation Pruning
Pruning Old Fruit Trees - Bryn Thomas of The Re: Generation Project
https://www.youtube.com/watch?v=SMBNw-mBUL8
Restoring Old Apple Tees - Parts 1 and 2 by Stephen Hayes
https://www.youtube.com/watch?v=ObAjCBTgOoY&list=PL0A8446E7E8D24B31
Renewal pruning of big apple tree with the Silky saw by Stephen Hayes (start at 3:00 and ignore wind sound - excellent demonstration of corrective open center pruning of younger 10 year old trees that have been neglected for last 5 years)
https://www.youtube.com/watch?v=p8QZD47fCEI
Apple tree restoration - thinning smaller branches by Stephen Hayes
https://www.youtube.com/watch?v=rBYp8V_cMFc&index=6&list=PL0A8446E7E8D24B31
Rejuvenate Mature Apple and Pear Trees (see excellent video within the article)
https://www.rhs.org.uk/advice/profile?pid=90
Fundamental responses to thinning and heading cuts from Penn State Extension
https://extension.psu.edu/fruit-tree-pruning-basic-principles
Summary Notes on Rejuvenation Pruning by Mike Chase
Below are a summary of the concepts covered in the above print and video resources:
1. Time required: The large, overgrown, neglected fruit tree has usually had several years where no pruning cuts to control tree shape were made. Usually, a neglected, overgrown tree can be returned to its original desired shape in three or four years, if it was originally trained as an open center (vase shaped) tree.
2. Rate of annual removal rate: Generally about a third of the existing extra, unwanted wood is removed each of the first three years through dormant season pruning. Most of this wood is found toward the center of the tree, often in the form of a "secondary canopy" that shades (kind of like an umbrella) the lower main scaffolds.
[ This secondary canopy is usually created by unchecked "water sprouts" that were growing almost vertically off of the scaffold branches (which were slanted at about 45 degrees out away from the trunk). These large vertically oriented limbs are the first ones to be removed when bringing a neglected tree back under control. ]
3. Necessity of summer pruning AND summer training to complement dormant season pruning: Since dormant season pruning of large diameter wood produces excessive vegetative growth, a great deal of summer pruning and limb training on new current year growth is required. One of three things must be done to each vertically oriented new shoot: 1. It can be headed to diminish apical dominance and create lateral branches. It can be headed out away from its origin if it is in a good place on the limb or it can be headed back close to its origin leaving a couple of buds to create short lateral fruit bearing limbs. 2. If it is in a good location to create a lateral limb it can be tied down at a 45 degree angle so that it becomes a fruit bearing limb. 3. It can be removed back to the branch collar. This is often done when there is a dense bunch of water shoots arising in one location. You might tie some off at 45 degree angels, head some others, and remove the rest.
This combination of dormant season and summer pruning plus training is assumed in pruning practices for maintaining the English home orchard, especially with respect to developing and maintaining the espalier fruit tree (see Richard Bird's Pruning Trees, Shrubs, and Climbers or Pruning Fruiting Plants).
4. "See" the original design (though the tangled mass of branches) A crucial first step (even before removing old and diseased wood, crossing branches, and pendent branches) is attempting to "see" what the tree would have been like if it had received regular pruning each year. This type of seeing is discovering the original structure, minus all of the extra limbs that have thrived during a long period of neglect. A good starting place is to look at some pictures of open center trees (vase style) at various stages of development. That tree that currently seems like a tangled web of branches, particularly in the center of the tree was once an open center tree (the use of central leader style is fairly recent, so it is likely an older tree was probably initially pruned in the open center style, not the central leader or modified central leader style). In the open center style, three or four main scaffold branches (tending toward being parallel with the ground) are equally spaced around the trunk. The diagram and photos below give us a picture of the goal we are striving for in our rejuvenating pruning work.
To the left is a diagram (viewed from above) of the desired scaffold structure of an open center tree. It has three main scaffolds going out in three directions from the central trunk. You sometimes see four scaffolds, but they are really hard to manage (gotta keep that center open to let in light and get to the fruit).
The secondary canopy obscures light getting down to this basic intended framework in an open center tree.
Below is an example of a young open center tree. Note that it has only three main scaffolds.
To the left are before and after pictures of a open center tree at 5 years. Notice the tendency in the before picture (immediately to the left of this text) to have lots of vegetative growth in the center that must be cut away to let sunlight and pickers into the tree. The after picture (b) in Figure 11 conforms very closely to the diagram up at the top of this section.
When an older tree goes unattended (not pruning on an annual basis) it really fills up the center which then needs to be removed in order to make the tree healthy and productive again. Also a neglected tree often develops a "secondary canopy" (from vertical water shoots fan out above the original tree that shades the primary scaffold structure that was formed when the tree was younger.
Below you see a tree with a large 60+ year old truck with new scaffold limbs that have about 5 years of growth. Remnants of the original scaffold branches can be seen radiating out from the truck. Since the new scaffold limbs were established the tree has has been maintained by annual dormant season pruning and some summer pruning to deal with water sprouts and other too vigorous growth. This is a beautiful example of a healthy, productive, renovated open center tree (except it could get crowed once again because they left 5, instead of only 3 or 4 main scaffold branches).
When an older tree goes unattended (not pruning on an annual basis) it really fills up the center which then needs to be removed in order to make the tree healthy and productive again. Also a neglected tree often develops a "secondary canopy" (from vertical water shoots fan out above the original tree that shades the primary scaffold structure that was formed when the tree was younger.
Below you see a tree with a large 60+ year old truck with new scaffold limbs that have about 5 years of growth. Remnants of the original scaffold branches can be seen radiating out from the truck. Since the new scaffold limbs were established the tree has has been maintained by annual dormant season pruning and some summer pruning to deal with water sprouts and other too vigorous growth. This is a beautiful example of a healthy, productive, renovated open center tree (except it could get crowed once again because they left 5, instead of only 3 or 4 main scaffold branches).
The above example is somewhat unique in renovation because the pruning has essentially produced a whole new open center tree with 5 year-old scaffolds on a 60 year old root system. More typically, renovation produces a more complex tree with sections that are old and sections that are new, as in the examples below. Sorry for leading with an atypical example but it beautifully illustrates the idea of "seeing" the open center that once existed and trying to recapture that original open center shape.
Now we move on to consider some of the typical renovations that are less perfect in execution.
Now we move on to consider some of the typical renovations that are less perfect in execution.
Above is a 50 to 60 year old tree in its second or third year of rehabilitation. You can see that the tree has been lowered and cleaned up on the left, right, and front side of the tree in past years (remember you generally only remove about 1/3 of the wood to be removed in any one year). And generally you remove the side toward the sun first because that allows light in on the rest of the tree that was obscured by the secondary canopy to the south. It appears he may be planning to make a cut this year at waist level (keeping the limb that goes out tot he right) but next year would make a cut about two feet below where he is currently standing (and maybe clear back to where this attaches to the the main 45 degree angle scaffold limb going out toward the left front). Can you "see" at one time this whole vertical limb was a water shoot going vertically off that scaffold limb? If he makes the cut at the scaffold limb next year then he would eliminate the secondary canopy completely and restore the tree to its original intended shape.
The 100+ year old multi-trunk tree pictured below poses a particular problem in renovation. It is often not clear whether all of the large trunk-like structures are all the same variety. Some may be rootstock and not the grafted variety (this is hinted at by the presence of root suckers visible around the base of the tree). The solution to identification is to check and mark each of the trunks as to whether they are rootstock or the grafted variety during the fruiting season in the fall. It is possible, though not likely, that all of the trunks are only rootstock (wild apple), and not the grafted variety (which may have died years ago). If a truck is only a rootstock then you could topwork that trunk and scaffold over to another variety (it need not be cut down).
In the event that all of the trunks are true to the grafted variety then during the firsts pruning year select among the two competing trunks over on the right side and take one out completely. Also in the first year take out several "secondary canopy limbs" (they go straight up off of the more horizontal (45 degree) scaffold branches). Lots of new growth will be stimulated. Remove much of the new growth during summer pruning. Head the rest back to get some side branching and fruit bud formation. Take off the remaining secondary canopy limbs in the second year.
Talk about not being symmetrical! Sometime the tree you want to save is in really bad condition like the one to the left. Note that the prominent vertical water sprout in the center of the picture is now about 5 or 6 inches in diameter and has side branches at about the 8 foot mark. This water sprout-based "tree" could be pruned into a producing tree within a tree. There are also other branches further out along the fallen trunk that appear to have already been pruned to be fruit producers. Although this horizontal tree may continue to produce fruit if properly maintained, it is always a good idea to use grafting or chip budding to make a reproduction of the variety onto a modern disease resistant rootstock like the Geneva series.
What we are looking at in this picture a somewhat typical situation where we have a scaffold lim with a bunch of upright (vertical) shoots that we need to make into productive fruit bearing branches. In the foreground leaning to the left is about a three inch (diameter) limb that was a water shoot that we are trying to rehabilitate Note that the three inch limb has been cut off at a slant just above a 3/4 inch limb that continues up out of the picture. The end of that 3/4 inch limb need to be tied off with twine so that it is going out at about a 45 degree angle so that it will set fruit buds (if it continues to go straight up it will not have fruit buds and will eventually (in 4 or 5 years start creating a secondary canopy). There are two little 1/2 twigs that have been cut back. Also on this three inch limb is another one inch limb that goes straight up but has a whole bunch of side branches. This is all last years wood and the side branching is the result of that branch being headed at the end of last year's growing season. When you head a branch you remove the apical dominance resulting in the desirable side branching. It it had not been headed back it would have grown very tall with no side branches. Further out on the scaffold is a big three inch diameter vertical water shoot that should be removed. When new shoots grow up from that cut they should be summer pruned back to a couple of bud that would then grow out more horizontally and form fruit buds.
Above is a 50 to 60 year old renovated tree that is again pretty productive. It will need annual pruning to avoid not developing a secondary canopy and filling the center with vegetation that prevents good light penetration.
A Note On Adventitious Buds
Adventitious cells, residing in the bark of trees, under the proper conditions (e.g., large wound from pruning) can develop into shoots, which can in turn develop into new limbs. This general principle can be used to help bring down the height and bring in the width of an overgrown, neglected tree. Thus, the large initial rejuvenating cuts give rise to new limbs that can be trained into fruit bearing limbs (tied off at a 45 degree angle), enabling us to further reduce the height and width by making additional cuts up to the newly formed limbs.
This is the principle that underlies the the use of the Dutch pruning cut (also known as a "renewal" cut) used to replace 1 to 3 inch diameter limbs on fruit trees in high-density plantings. This branch renewal practice in high-density orchards involves cutting off the largest limb or limbs on a producing fruit tree in an annual rotation beginning in the fourth or fifth year. Instead of cutting at the branch collar, a cut in branch renewal is made that leaves a short stub. Although there may not be any evident buds in the stub that remains to regrow the limb, some will usually appear by the first of June. One of the adventitious shoots is selected and trained as the replacement limb for that section of the leader and the others rubbed off. Research shows that the angle of the renewal cut doesn't matter. It can be up-facing like the Dutch cut, a down-facing cut, or a perpendicular. A shorter cut is better (keep it between .5 cm and 1.5 cm - but not flush at the branch collar).
A Note On Adventitious Buds
Adventitious cells, residing in the bark of trees, under the proper conditions (e.g., large wound from pruning) can develop into shoots, which can in turn develop into new limbs. This general principle can be used to help bring down the height and bring in the width of an overgrown, neglected tree. Thus, the large initial rejuvenating cuts give rise to new limbs that can be trained into fruit bearing limbs (tied off at a 45 degree angle), enabling us to further reduce the height and width by making additional cuts up to the newly formed limbs.
This is the principle that underlies the the use of the Dutch pruning cut (also known as a "renewal" cut) used to replace 1 to 3 inch diameter limbs on fruit trees in high-density plantings. This branch renewal practice in high-density orchards involves cutting off the largest limb or limbs on a producing fruit tree in an annual rotation beginning in the fourth or fifth year. Instead of cutting at the branch collar, a cut in branch renewal is made that leaves a short stub. Although there may not be any evident buds in the stub that remains to regrow the limb, some will usually appear by the first of June. One of the adventitious shoots is selected and trained as the replacement limb for that section of the leader and the others rubbed off. Research shows that the angle of the renewal cut doesn't matter. It can be up-facing like the Dutch cut, a down-facing cut, or a perpendicular. A shorter cut is better (keep it between .5 cm and 1.5 cm - but not flush at the branch collar).
In the case of the limb to the right, adventitious shoots appeared on the limb after a major rejuvenation cut out at the end of the limb during the previous dormant season. Those adventitious shoots grew into water sprouts during the year (and now have to be removed). However, in June a few of them could have been selected as new side branches and tied down to 45 to 90 degrees to form new fruiting branches. The rest could have been rubbed off at that time. Instead of cutting off all of these water sprouts off now, some could be selected and tied off at 45 to 90 degrees to form new side branches, with the remainder being removed.
Below are some examples of adventitious shoots that develop from severe pruning. In these examples you also see the resilience of trees to severe pruning.
The trees above were moved a few months prior to the picture to this location in Da Nang, Vietnam, after being dug up to make room for construction projects in the city. In the process of moving, large amounts of top and roots were removed. They are now in temporary "pots" made of discarded sheet metal. The bottom of the roots are now at ground level in these makeshift pots. They are being rejuvenated and will be sold as shade trees for new homes and businesses being built in Da Nang.
Note how many big 5" and 6" cuts were made. There are, however, a few 1" to 2 1/2" branches that weren't cut off to serve as nurse branches. Also note the development of new shoots on most of the big scaffold branches and the trunk.
Here is an example of the desired end product, a nice looking tree with the limbs you would expect to see on a decorative tree. This tree has been placed in a concrete pot and is ready to go out to a customer.
Note the little adventitious shoots arising form the bark. They will eventually grow into limbs that will give the rejuvenated tree its shape.
Another example of adventitious shoot on a different kind of tree.
Note the proliferation of adventitious shoots on the tree above that was moved only a few months ago, with major cuts to its larger branches. To a lesser degree this kind of shoot development occurs in apples, pears, and stone fruit that have been severely pruned. So the application to rejuvenating fruit trees in the Northwest is that the major cuts used in fruit tree rejuvenation also results in the development of adventitious shoots on the surface of the bark that can be developed into fruit bearing limbs.