Horridculture – Sealant

P90810++++Grafting compound is a thick sealant applied to a fresh graft union to limit desiccation while the graft knits. A bit more typically gets applied to the cut distal end of the scion. There are various formulations of grafting compound, ranging from something resembling roof patch to a something with the consistency of thick paint.

The stuff, as sloppy and icky as it is, really is helpful. I can not imagine how big orchards were grafted before it was invented.

It is also useful for keeping cane borers out of the cut ends of freshly pruned roses. For those of us who remember how to prune roses properly, leaving only a few thick canes, grafting compound really is practical. I just don’t use it on roses because cane borers are not a problem here.

Since I do not use grafting compound on roses, and the plants that I graft do not need grafting compound, I presently have no use for it. I suppose I could use it on apple and pear trees, but it really is not necessary. When I get around to grafting apricots and peaches, it will only be for a few trees in my own garden, so I will just use candle wax.

This surprises people. At work, I am often asked about ‘painting’ pruning wounds and shiners as trees get pruned, presumably with sealant. Decades ago, it was actually commonly done. Even when I did my internship in arboriculture in 1988, some arborists were applying sealant because it was easier than arguing with their clients about it not being necessary.

The problem with applying sealant to large wounds is that is actually seals moisture within the otherwise exposed wood, and promotes rot. It is best to do nothing, and allow the affected trees to compartmentalize their wounds as they would do naturally if limbs were broken off by the weather. Trees know more about their processes than we do.


Arborists Maintain The Big Trees

91106thumbThe trees know what time of year it is. Even evergreen trees have shed some of their older foliage through late summer. Deciduous trees generally start later, but will be more blatant about their process as they defoliate completely through autumn to winter. Some get strikingly colorful first, as if to brag about it. Foliage is not so important during shorter days and dimmed sunlight anyway.

By the time storms start to arrive later in autumn, trees intend to be ready. There will be less foliage to be blown by wind, or to absorb the weight of the rain. Remaining deciduous foliage is likely to be dislodged by wind and rain before supporting limbs succumb. Trees will be mostly dormant, so will not mind so much if a few minor limbs do happen to get broken. They know their routine.

For many types of trees, this is a the best season for major pruning. While dormant, they are much less likely to be offended by it. In fact, they sort of expect to wake up in spring with a few limbs missing. They do not distinguish what was pruned away from what might have been broken by the weather. Besides, it is better to prune questionable limbs civilly, before they get broken brutally.

Trees that are beyond reach will need the attention of professional arborists.

Arboriculture is merely the horticulture of trees. An arborist is therefore a horticulturist who specializes in trees. They assess the health, stability and structural integrity of trees, and prescribe any necessary arboricultural procedures. They or their associated crews are qualified to perform the work that the trees need. The most proficient of arborists are those who are certified with the ISA.

The ISA is the International Society of Arboriculture. ISA Certified Arborists have passed an examination of their arboricultural expertise, and maintain their credentials by continued involvement with ISA educational seminars, classes and workshops. Information about the International Society of Arboriculture and local certified arborists can be found at their website, www.isa-arbor.com.

Work Day Renovation Of A Flowering Crabapple

P91020P91020+It is amazing what just a few parishioners and friends can accomplish in just a few hours from about nine to noon on Saturday morning. It is only happens a few times through the year, so we make the most of it to catch up on all sorts of maintenance and projects at Felton Presbyterian Church. (My parish should do this sort of thing.) I was there to work in the minimal landscape.

I started working with this ‘Prairie Fire’ flowering crabapple several years ago. As I pruned for clearance above the adjacent parking spaces and patio, I retained lower growth in the space in between. The tree bloomed too nicely to unnecessarily remove all that was right where it was most visible. Besides, from the patio, it was more visually appealing than a view of parked cars.

Then, I missed a work day. There were plenty of volunteers. There were plenty of power tools. There was plenty of enthusiasm. There was no horticultural expertise. Someone decided that my once exemplary flowering crabapple was in need of pruning, so executed the task with power hedge shears. The damage is irreparable. Lower growth is gone. Upper growth is mutilated.

It was very discouraging. It was done out of season, so I could do nothing to start to repair the damage at the time. There was not much left to repair anyway. I could only let the tree grow through a season so that there would be something to work with later.

Well, this was later. I would have preferred to wait for complete defoliation, but the tree is starting to go dormant now, which is technically good enough. I also would have preferred to prune less away; but really wanted to remove as much of the disfigured growth as possible.

I am less than pleased with the results. With all the disfigured lower growth removed, only the new upper canopy remains. The tree got what my colleagues might refer to as an ‘Ethiopia cut’, which is what much taller trees in Ethiopia get when their lower growth gets eaten by giraffes. It will be a long recovery.

The upper picture is the ‘before’ picture. The bright sunlight at noon does not look so good in the lower ‘after’ picture. I mentioned the Work Day and an update in my other blog, Felton League.


Horridculture – Sign Up

P91016Perhaps the signs should be down instead. They are obscured by the crape myrtles where they are now. They would be more visible if they were either higher or lower, but not in line with all these trees. The trees were planted only a few years ago, but have done very well. Lodgepoles need to be removed. The specimen to the left is recovering well from earlier disfigurement.

Selection of trees for parking lots is not easy. Such trees must disperse complaisant roots that are not likely to displace pavement or curbs. They should should be reasonably high branched and conducive to pruning for clearance above parked cars, and where necessary, for delivery trucks. Excessive floral or foliar mess would be a problem. So would fruit that attracts wildlife.

Unfortunately, not many trees conform to all limitations. Those with the most complaisant roots do not get big enough to be pruned up high enough for adequate clearance, or even provide significant shade over the often hot black pavement below. Since shade is the primary function of such trees, an abundance of diminutive trees often compensate for fewer substantial trees.

This presents another range of problems. The smaller trees can be pruned for minimal clearance above pedestrians and parked cars, but not delivery trucks. What is worse is that they can not be pruned above lighting and shop signs either. Pruning them lower than the signs instead would only work if the signs were to be viewed horizontally, from the same height as the signs.

Nonetheless, that is what is most commonly done. This is the result. All those flashy and expensive signs on the buildings in the distance are mostly obscured from this vantage. Fortunately, the honey locusts closer to the signs can be pruned up higher for adequate clearance.

The Wrath Of Grapes

P91006Jocular reference was made to ‘The Grapes Of Wrath’ on our our backward version on the way to Oklahoma several years ago. We happened to drive through Salinas, where author John Steinbeck was from, and Bakersfield near Weedpatch, where the migration from Oklahoma in the story ended. From there, we literally drove the same route from Oklahoma, but in reverse.

I never read ‘The Grapes Of Wrath’.

I do enjoy growing the sort of grape vines that some of us grow in our home gardens for fruit that can be eaten fresh. (I loath wine grapes and vineyards, but that is another topic for later.) There happens to be a nice big unidentified grapevine at work that needed major pruning last winter. It was a sloppy and formerly unpruned mess, with rampant long canes strewn about.

Some of these canes developed roots where they had been laying on the ground long enough to do so. The process is simply and conveniently known as ‘layering’. It is actually a technique for propagation that is sometimes done intentionally to plants that are not doing it naturally, (Again, that is another topic for later.) After giving a few rooted canes away, there were a few extra.

Since last winter, seven copies of the original grapevine are still here! I really do not know what to do with them. I could give them to neighbors before the end of this winter, but would then worry about them not getting the annual pruning they need, and overwhelming the landscapes they inhabit, just like the original vine did. Even in their cans, they are already a sloppy mess.

Many surplus plants are accumulating here. Many will go into landscapes as rainy weather starts. However, there are a few that will not be so easy to accommodate.

Horridculture – Opposite Poles

P90904This is not about North and South. It is about a utility pole and a pole that remained from a redwood tree that was too close to it. One is there to support a variety of cables and a streetlamp. The other just wanted to grow into a redwood tree to join the rest of the forest. One has been deceased for many years or decades. The other was alive just recently, but is now only a stump.

The picture above shows how many cables the utility pole supports, as well as the streetlamp. When I did my internship in 1988, the arborists whom I worked with knew what each of the various cables were for; high voltage, lower voltage, cable television, telephone and whatever else was up there. Fiber optic cables have since simplified the telephone and television cables.

The picture above also shows how the unfortunate redwood tree needed to be cut back for clearance from the electrical cables. I was mortified to see this so prominently visible on the edge of a main road, because I should have noticed the problem earlier and just cut the tree down. Not too long ago I was pruning many other redwood trees for clearance from other streetlamps.

Those who pruned it instead, along with any other trees that were encroaching into the electrical cables, were very efficient with establishing clearance, but not so proficient with aesthetics. Obviously, I could not leave this tree like this on the side of the road. Even if I did not care what it looked like, I did not want it to regenerate and immediately encroach back into the cables.

The picture below shows my corrective pruning. The stump is certainly not dead, and will try to regenerate, but will be easier to keep down. If kept down long enough, it may eventually die.

The second picture below shows the stripped trunk in two sections that are nearly eight feet long, and a short bottom section that is a bit more than two feet long. The two long sections are straight enough for gate posts (although there is another plan for them). It is a sad demise for the formerly healthy and sound redwood tree, but became necessary to keep the electricity on.P90904+P90904++

Bad Pollard

P90831KJust about any other arborist will insist that any pollard is a bad pollard. I am not any other arborist. I have no issue with pollarding certain trees properly.

Pollarding is severe pruning that removes all growth that developed since the last pollarding procedure, leaving only a main trunk and a few main limbs. It is done while trees are dormant in winter, and must be repeated either annually or at least every few years, before the resulting growth develops into major limbs. Pruning must be very thorough and neat, leaving no stubs.

Most new growth develops from where older growth had been pruned away during the previous winter, with only a few adventitious stems possibly developing on the main limbs or trunks. Distended ‘knuckles’ develop where this growth repeatedly gets pruned away and regenerates. All subsequent pollard pruning must be done only on the outside of these knuckles, not below.

It may seem easier to cut entire knuckles off with fewer big cuts rather than cutting all the secondary growth off with so many more cuts. However, as new growth develops, the many small cuts on the distended knuckles will be compartmentalized (healed over) much more efficiently than fewer but larger wounds. Wounds that compartmentalize too slowly stay open to decay.

Once pollarded, a tree will always need to be pollarded, or at lease pruned regularly to compensate for compromised structural integrity. Secondary growth is innately vigorous and heavy, but weakly attached to the main limbs.

Pollarding is done to produce an abundance of lush foliage, to produce an abundance of twiggy growth, or to deprive a tree of bloom. Pollarded mulberry trees provide lush foliage to feed silkworms. Pollarded willow trees provide many uniform limber canes for basketry. Pollarded privets are unable to bloom and bother those who are allergic to their objectionably fine pollen.

Well, enough about pollarding.

I pollarded a blue gum, Eucalyptus globulus, for the second time earlier this year. It was done dangerously late in the season, and at the same time that the roots of the tree were brutally damaged by relocation. (It is a canned tree that rooted into the ground.) The tree has no branches, but only a single ridiculously bare trunk with a silly new knuckle on top. Oh, the shame!

As you can see, the unfortunate tree has not grown much since then. It is now getting to be September, so the tree will not be growing much through autumn. As much as I would prefer to pollard this tree annually, I will likely not pollard it this winter, but instead let it grow for another year before pollarding it again. The blue juvenile foliage is exquisitely aromatic, but scarce.

For this picture, I could have moved the tree away from the fence that it is tied to for support, but the barbed wire somehow seems appropriate.

Six on Saturday: The Shining


‘Shiners’ have nothing to do with Rudbeckia hirta, which is commonly known as ‘black eyed Susan’. (Why did rude Becky hurt Susan like that anyway?) Shiners are the wounds left from pruning significant limbs from their supporting limbs or main trunks. They shine most blatantly when fresh, and then fade in the weather.

The best shiners are those that will be compartmentalized (healed over) most efficiently. They should not be cut too deeply, or be left with stubs that interfere with compartmentalization. There is quite a bit of science to shiners.

1. This is a good example of a bad shiner. (I could have gotten a better picture of it, but thought that the sun shining from behind was appropriate to the topic.) This shiner was not made by pruning a limb away from a main trunk, but by pruning a main trunk away from a limb. The main trunk leans over so much that most of it needed to be removed to maintain minimal clearance over a driveway. The only two options were to prune it back the the limb on the left, or remove the entire tree. Because the shiner is wider than the remaining limb, which will become the main trunk, it will take several years to be compartmentalized. By that time, decay will have extended downward from the shiner into the main trunk below.P90824

2. Removal of a limb that was battering the topsides of delivery trucks left the shiner above and left of the center of the picture. The scar to the lower left of the shiner, and another scar farther the lower right, closer to the lower right corner of the picture, were caused by a single altercation with one truck that drove off the edge of the driveway. Since it is not really encroaching into the driveway, or interfering with minimal clearance, this particular damaged limb remains.P90824+

3. This is the thrashed limb that was removed from the limb in the #2 picture above. The freshest damage is still red. This limb had been up above minimal clearance for a few years before the supporting limb sagged with the weight of the growing canopy above. Damage to the trucks is more of a concern than the limbs, so it had to go.P90824++

4. This is another good example of a bad shiner. The main trunk to the right would not have been able to compartmentalize over the stub until it grew out past it, or the stub rotted and fell away. The stub was partly rotten, but also partly viable, with a small branch growing from it. The viable portion would have taken more time to rot away. The whole mess was cut away after this picture was taken; but the resulting shiner that I did not get pictures of has another problem. This picture shows how the stub wraps around the main trunk from behind. The bark compressed between the stub and the main trunk, which is known as ‘included bark’ or ‘bark inclusion’, will temporarily be in the way of compartmentalization of the shiner. Fortunately, the tree is young and vigorous enough to figure it all out.P90824+++

5. What looks like shark jaw bones without the teeth is the callus growth that once surrounded a well cut shiner. After the shiner was cut, and the tree started to compartmentalize over it, the tree died suddenly. As the trunk decayed, this dense callus growth that started to compartmentalize the shiner decayed slower. The uniformity of the callus growth shows how evenly the shiner was cut. I believe that the bottom of the shiner is to the left, but that could be backward. I can only say that the shiner is sideways in this picture.P90824++++

6. Coast live oak, Quercus agrifolia, is the only species in all five of the pictures above, and also provided the biscuits to the lower left and the upper right in this picture. ‘Biscuits’ are sometimes cut to adjust a shiner after the main part of a limb is pruned away, or perhaps to cut a stump slighter lower after a tree is cut down. I really do not remember why I saved the biscuit to the lower left, although I can remember the tree that it came from. The fresher one to the upper right is from the shiner in the first picture #1 above. I kept the Hollywood juniper biscuit to the upper left because I thought it would smell like the related Eastern red cedar (which is actually a juniper rather than a cedar) that cedar chests and closets are made with. The deteriorating biscuit to the lower right is from a very dead white fir that needed to be cut down. I kept it because I happen to be very fond of white firs, but so rarely see them here.P90824+++++

This is the link for Six on Saturday, for anyone else who would like to participate:


Horridculture – Stumpy

P90814Among pines, firs, redwoods and most excurrent trees (with central leader trunks), stubs or stumps of limbs that were shed are common and more apparent than they are among decurrent trees (which branch into many main limbs). The older lower stubs slowly but eventually decay and fall away as the trunks compartmentalize (heal over) where they were formerly attached.

However, wild trees are rarely completely without such stubs. As the older lower stubs are shed, newer stubs develop higher up. The worst of their stubs get pruned away only when more refined landscapes are developed around such trees, and they get pruned accordingly. If the trees get groomed regularly every few years or so, not many new stubs get a chance to develop.

When pruning out viable limbs, they must be cut cleanly from the trunk or supporting limb, without stubs. Since they do not deteriorate slowly before falling away, the trunk or supporting limb has no time to start the process of compartmentalizing (healing) over where such limbs were attached. Cutting away cleanly eliminates as much obstruction to that process as possible.

Pruning necrotic stubs from trunks of excurrent trees is not quite so important because the trunks have a tendency to start the process of compartmentalization as such stubs are decaying, and can actually constrict and crush stubs if they do not fall away efficiently enough. Nonetheless, necrotic stubs get pruned out when trees are groomed, just because they are unappealing.

So, no matter what, stubs should not be left when pruning. It is not complicated. It is actually easier to control a saw when it is up against a tree trunk or main limb. Yet, many who do not know better, and many who really should, more often than not, leave trees looking like this fir tree.

No Cherry On Top

P90811Weeping flowering cherry is another type of tree that almost never gets appreciated like it should. Like so many Japanese maples, they get planted into situation where so-called ‘gardeners’ shear them into nondescript globs of worthless foliage that only get in the way. Some get shorn so regularly that they are deprived of bloom. Their form and bloom are their two main assets.

The climate here is not easy on them either. Although comfortably mild, the climate is also arid. This aridity enhances the potential for sun scald of exposed bark. Because upper limbs bend over to hang back downward, their bark is more exposed than that of upright flowering cherries. Consequently, upper limbs are often scalded and ruined, disfiguring the remaining canopy.

Pruning can be complicated. Removal of scalded upper growth exposes inner growth that is more sensitive to scald. It is sometimes necessary to leave damaged upper growth until it gets replaced from below by newer growth. Regular pruning to remove as much of the superfluous lower growth as possible should stimulate more vigorous growth among the stems that remain.

This is really the best technique for preventing scald among upper growth. It may sound silly, but pruning from below to concentrate growth into fewer stems that extend from or through the top of the canopy keeps the top of the canopy healthy and resilient to scald. It also elevates the pendulous canopy that needs to be pruned very regularly for vertical clearance anyway.

It is not easy to see in this picture, but this small weeping cherry tree is developing two distinct canopies. The original upper canopy was damaged by scald and is now disfigured. It is mostly to the upper left of center of the picture. A more symmetrical inner canopy that is developing where superfluous inner growth was pruned out last winter is evident below and to the right.

If there were not a walkway so close to the tree, and I were not concerned with maintaining vertical clearance, I could prune the upper canopy back over a few years, and subordinate it to the healthier lower canopy as it grows through it. Instead, I will prune out most of the inner canopy, leaving only a few vigorous stems that can replace what is missing in the upper canopy.

There is no need to be concerned with it now. The lower stems are not too obtrusive yet. They can bloom next spring, and get pruned out next summer before they really do get obtrusive.