Pin Oak

Pin oak is not drought tolerant.

There are several oaks, especially natives, that do not need much more water than they get from rain. Pin oak, Quercus palustris, is not one of them. It is naturally endemic to areas that are damp or swampy for part of the year. It is more tolerant than others are to lawn irrigation, but is also more sensitive to drought.

Compared to other oaks, pin oak grows fast while young. It can get two stories tall in about ten years. Then, it takes more than twice as long to double in size. Old trees do not get much more than fifty feet tall, with trunks nearly three feet wide.

The deciduous foliage turns as brown as a grocery bag in autumn, and may linger late into winter, or until it gets replaced by new foliage in spring. The distinctively deeply lobed leaves are about two to five inches long, and about two thirds as wide. Each leaf has five or seven lobes. Each lobe has five to seven teeth.


Flagging (sudden necrosis of distal foliage) used to indicate the beginning of a sudden end.

Phytophthora ramorum is the pathogen that initiates Sudden Oak Death Syndrome, which is known simply as SODS. Monarthrum scutellare, which are known as ambrosia beetles, and are the secondary pathogen associated with the syndrome, infest and kill tanoak and coast live oak that are infested with Phytophthora ramorum, about as quickly as symptoms are observable.

Hypoxylon thouarsianum is a tertiary but merely opportunistic pathogen associated with the syndrome. By the time it gets established within galleries excavated by the ambrosia beetles, the affected trees are almost completely necrotic. That first ‘S’ in SODS is there for a reason. It is an efficient process. Death occurs too suddenly for affected trees to drop any of their leaves!

Each of these three pathogens causes distinct symptoms. Phytophthora ramorum causes trees to bleed black tar-like fluid, and causes tanoak to exhibit foliar flagging as seen in the picture above. Monarthrum scutellare expels finely textured frass from the galleries it excavates into infected trees. Hypoxylon thouarsianum produces distinct small and black fruiting structures.

In the past several years though, Sudden Oak Death Syndrome has often been a bit less than sudden. There are a few tanoaks here that have exhibited foliar flagging for a few consecutive years, without any bleeding from the trunk or infestation by ambrosia beetle. Some coast live oaks have exhibited minor bleeding, but likewise have not become infested by ambrosia beetle.

It is as if the ambrosia beetle is no longer proliferating as it had been. It actually seems to be rather scarce. Trees that were expected to succumb suddenly to ambrosia beetle infestation are succumbing slower to infestation of only Phytophthora ramorum. The process is variable, so might have potential to kill some trees rather suddenly, but may take a few years to kill others.

Could some possibly survive?


P90901It has been almost a month since one of three small but sculptural and very prominent coast live oaks at work was destabilized by . . . well, children. They were climbing on it, as most good children should do. There were a few of them; and the tree is old and deteriorating. All three of the trees actually grew from the same rotten stump of a tree that was cut down decades ago.

I wrote about it at ‘Six on Saturday – Do Not Sit On Tree‘. The title will make more sense if you read about it.

To salvage the tree, I pruned off as much of the foliar canopy as possible. This eliminated some of the weight that the trunk needs to support, as well as decreased some of the resistance to wind, which exerts leverage against the compromised root system when wind blows. Sawhorses were placed under the trunk, and one of the others, to prevent them from sagging any lower.

Props that were fabricated to be more permanent then the sawhorses were installed last week. They do not actually support or even touch the trunks, but are there to prevent the trunks from sagging any lower. If the trunks start to lean on the props, I will prune a bit more weight off. If that doesn’t work, the props can be moved a bit farther out, where the trunk are higher.

Hopefully, the old root system of the destabilized tree was not so severely damaged that it can not recover. If it does recover, and the trunk is not supported by the new prop, the tree will need to eventually regain stability. It will be a tediously slow process. Because the trees are already so mature and disfigured, the props will likely never be removed, regardless of recovery.

The first picture above show the destabilized tree outfitted with a new prop. The second picture below shows the other tree that was outfitted with a new prop just because it is so likely to become destabilized.


Six on Saturday: Do Not Sit On Tree


1. Seriously!P90810

2. Allow me to explain. This is one of three small but very gnarly coast live oaks that grew from the roots of a single tree that was cut down or fell several decades ago. Because the trunks of the three trees are so horizontal and sculptural, children climb on them. Sometimes many children sit on the trunk of this particular tree to get their group picture taken. We had been concerned about how this might compromise the stability of the tree for quite a while. Before we constructed suspension devices to prop it and one of the other two trees with, it destabilized and sagged! We pruned much of the canopy away to eliminate some of the weight that exerts so much leverage against the root system, and propped the trunk with a saw horse. We hope that the tree survives the loss of roots that likely broke away in the process, but would not be surprised if it does not. We are not ready to cut it down. It and the two other trees are so well known and popular among guests. The sign is visible to the right. I will explain the colored yarn on the trunk in a moment.P90810+

3. The subject tree is to the lower right in this picture. The two other trees are sprawled to the upper left. The tree that extends farthest to the left will get propped as well. All three have been pruned more aggressively than they should have been to eliminate much of the weight.P90810++

4. The yarn on the trunks is decoration that the camp counselors installed prior to the arrival of the guests. It must have taken a long time to wrap this much yarn around the trunks, and there is a whole lot more in many other trees. I wrote about it earlier in ‘Boom! Zap! Wow! Bam! Zing!‘.P90810+++

5. This is a completely different coast live oak, with a completely different problem. It needed to be pruned for clearance from an adjacent roadway and walkway. The major limb that was here supported less than one tenth of the total canopy, but because it had been cut back repeatedly, it was unusually bulky. Consequently, the shiner that remains is about as wide ad the remaining trunk! That is VERY arboriculturally incorrect. To make matters worse, the cut was not at the correct angle, so eliminated the lower half of the ‘collar’ that is supposed to expand to compartmentalize (heal) the shiner. The problem now is that by the time the shiner heals, the interior of the trunk may be so rotten that the tree may need to be removed anyway. The limb needed to be removed. The only other option was to remove the entire tree.P90810++++

6. Nothing was done to this coast live oak. It grew like this naturally. Although not an exemplary specimen, it certainly is impressive.P90810+++++

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

Coast Live Oak

90522The valley oak of the Sacramento Valley, San Joaquin Valley, and coastal valleys to the west, is the grandest oak of North America. Within the coastal half of that range, and extending down past San Diego, the coat live oak, Quercus agrifolia, is a nearly comparable second grandest. The biggest subjects may be as tall as seventy feet, and nearly as wide, with trunks wider than ten feet!

However, there is significant variability. Trees in forest situations do not get as big, and may stay lower than twenty five feet, with shrubby branch structure. While the biggest can get older than two centuries, smaller trees may not live half as long. The canopies of exposed solitary trees might reach the ground, while more social or sheltered trees are likely to shed lower growth with maturity.

Coast live oaks are typically pretty gnarly, and many have multiple flaring trunks. The dark evergreen leaves are only about an inch or two long, and half as wide, with bristly teeth on convex edges. The narrow inch long acorns can be messy. Roots are very sensitive to excavation and excessive irrigation. Sudden Oak Death Syndrome prevents new trees for getting planted in many regions.

Mighty Oaks From Little Acorns

90522thumbOak, which might seem to be obvious to many of us, was identified by the Arbor Day Foundation as the People’s Choice for American’s National Tree. We certainly like our redwoods and exotic palms in California. Quaking aspen and blue spruce are probably favorites in Colorado. Sugar maple must be the most popular in Vermont. Yet, everyone appreciates the mighty American oaks.

Connecticut, Georgia, Illinois, Iowa, Maryland, New Jersey and the District of Columbia each have an oak as the official state tree. ‘Oak’ is one of the more traditional names for streets and roads throughout America. Just in California, at least eight towns are named after oaks, both in English and Spanish. Oaks put the ‘oak’ in Oaklahoma! (Oakay, maybe that last one is an exaggeration.)

So, now that we know that oak is what most Americans want to be the National Tree, does anyone know what species the oak should be? Well, that will take a bit more work. There are so many in America. There are too many to select from just in California! They are each so unique too. Some grow into grand trees. Others are shrubby scrub oaks. They might be deciduous or evergreen.

It is important to be aware that, just because oaks are the most popular trees in America, they are not necessarily appropriate for home gardens. Some, particularly in California, are best in the wild outside of landscaped areas. Some get too big. Some are too messy with acorns and leaves that fall slowly for a long time, either evergreen or deciduous. Some are susceptible to disease.

It is also important to be aware that big mature oaks, as rugged as the seem to be, are remarkably sensitive to modifications to their environment. Wild oaks that matured in areas that were not landscaped can succumb to rot in only a few years if the ground below them gets landscaped and regularly watered. Oaks planted into new landscapes adapt to the watering they get while young.

For landscapes that can accommodate them, oaks are grand and elegant shade trees that last a lifetime. There are many good reasons for their popularity.


Apologies for posting tomorrow’s article today. Today’s article will be posted tomorrow.

Not My Style

P90202KThere is no shortage of artistic pictures online and within the context of gardening blogs. Some really are fascinating. I particularly like those that show the weather in far away and mythical lands like Colorado, Chicago, North Carolina, Australia, Oklahoma, New Zealand, Austin, and South Africa. Then there are the cats, dogs, hens, horses, pigs, and a few others that are not so entertaining. The close ups of flowers, fruits, leaves, mushrooms and any variety of odds and ends are amusing if they are not immediately recognizable. Yet, all these pictures are not my style. I am not the artistic sort.

I will try though. This shiny chestnut brown acorn half shell just looked like something that I should get a picture of. It was just laying there on the big sycamore leaf as if it were on display. The interior is even shinier and more richly colored than the exterior, although I did not turn it over to confirm. I am just guessing from my experience with other acorns.

The sycamore that provided the leaf is a California sycamore, Platanus racemosa.

I could not identify the species of the oak that provided the acorn. I am pretty certain that it is not from a coast live oak, valley oak, black oak or tanoak; respectively, Quercus agrifolia, Quercus lobata, Quercus kelogii or (Notho)Lithocarpus densiflorus. There are not many other options. I suspect that it could be from a canyon live oak or Shreve oak; respectively, Quercus chrysolepis or Quercus parvula ‘Shrevei’. Neither produces acorns that are typically as round as this one was.

Nor could I identify the species of squirrel, rat, raccoon, crow or whatever unknown animal dropped it.

Well, perhaps this is why I am not the artistic sort. I am instead the technical sort.

California Black Oak

81003The most popular hardwood in California is essentially unavailable in nurseries. California black oak, Quercus kelloggii, provides between a quarter and a third of the hardwood timber harvested in California. One would not know it by its sporadic appearance within mixed forests of the Coastal Ranges. It is much more common in the Sierra Nevada, which might be why no one grows it.

Mature trees can top out at thirty feet with broad canopies if well exposed, or might be more than seventy feet tall and relatively slender if they must compete with other trees. The biggest trees are more than a hundred feet tall. The sculptural trunks are usually less then four feet wide. Trunks of old trees are commonly rotten inside. Gray and smooth young bark gets rough and dark with age.

The distinctively lobed deciduous leaves of California black oak are not much more than four inches long. They can get nearly twice as long on the most vigorous growth, or where shaded. The dark green foliage will slowly turn brown or yellow through autumn, and then defoliate through winter. It can turn a brighter yellow or orange, but then defoliates faster, if the weather gets cool fast.

Illegally Planting!

P80902K“ . . . others illegally planting whatever they wish . . . illegally.” Someone actually said that about the installation of our little Memorial Tree in Felton Covered Bridge Park. It was within the context of a review of the Park on Facebook, written by someone who has not stopped complaining about Felton since she moved here. It was forwarded to me quite some time ago by someone who documents and files such information that is relevant to hate crimes, and what is now known as ‘hate speech’, which is another completely different topic that we can not get involved with here.

Technically, it is accurate. The tree was planted without a permit, and does not comply with the standards of Santa Cruz County Parks. Compliance would have been quite an expensive imposition. It would have required an expensive #15 (15 gallon) tree, outfitted with lodgepole stakes and straps. The overworked gardener would have needed to take time from his busy schedule to install it. Because the irrigation system to the site is now defunct, the gardener would have needed to irrigate the tree until it got established. It was easier, much less expensive, more horticulturally correct, and socially responsible for us install the tree and maintain it on our own. Call 911 if you must.

There are of course reasons why we should not plant trees or other plant material in parks and public places. We do not want to make more work for gardeners, interfere with the landscape plan, or add plants that are inappropriate to the situation. This Memorial Tree happened to have been planted with the supervision of a horticulturist and arborist (me), on the exact spot where another oak that was installed with the original landscape had been knocked down by a car. Otherwise, in most places in Felton Covered Park, vegetation management, including the removal of large volumes of biomass and invasive exotic specie, should be the priority. (Unfortunately, the overgrowth of invasive exotics is mostly within a protected environmentally sensitive riparian zone.)

The little Memorial Tree has quite a history, even though it is still a baby. I do not want to post links to all the other updates about it, but I can post this link to another article that contains another link to others . . . Oh, you can figure it out if you like: .


P80902KThere is NO news regarding the tiny Memorial Tree in Felton Covered Bridge Park that I so frequently provide updates for. It did not do much this year. I probably already mentioned this when it was busy not doing much in spring. It is in a difficult situation, where too many dogs do what dogs do to tiny valley oaks that are busy not doing much more than trying to survive without regular watering, out in a harshly exposed island in a parking lot. Once it gets going, it should do fine. It is only slow now, but is not unhealthy. It is doing exactly what it should be doing this time of year. By late autumn, it will try to defoliate. Valley oaks are never in a rush for that.P80902K+
This angel’s trumpet is more interesting because it was seemingly deceased. As you can see, it is trying to recover . . . just in time for autumn. Unfortunately, there will not be sufficient time and warm weather for it to mature enough for the new stems to survive even a mild frost next winter. At least it will get a bit of time to recharge the roots so that it can regenerate a bit more vigorously next spring.
There is of course the possibility that it will not get frosted too severely in winter. It is somewhat sheltered by the canopies of nearby trees. We may even try to protect it under a box on the coldest nights.
Realistically though, the loss of such minor growth would not hurt it much. As it matures, it will likely lose much or most of its outer foliar growth annually each winter, and then replace it with new growth each spring. The priority for it now, or at least next spring, is to develop substantial stems that are above where ‘gardeners’ will cut it down with a weed whacker. Once it does that, it will have a relatively permanent framework of resilient trunks that it can get frosted back to.
The main problem since it was installed was not the frost, but unskilled labor with weed whackers. No matter how emphatically we explain to the ‘gardener’ that it is not a weed, his crew cuts it down a few times annually when no one is there to stop them.P80902K++
Naked ladies continue to bloom all over the region. These happen to be in the parking lot of Felton Covered Bridge Park. Several that were surplus in a neighbor’s garden were planted in the corners of the various islands. Unfortunately, because of their locations, most of their flower stalks get trampled and broken off. The picture below shows how exposed they are within an area of substantial traffic. The foliage that develops later does considerably better. It is too substantial to be trampled and ruined completely, and it gets a bit more substantial every year. However, the substantial foliage is not here yet to prevent the flower stalks from getting trampled.P80902K+++
By the way, if you think that I wrote this post because of the (former) lack of a horticulturally oriented topic for today, you are correct.