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Care for the future, care for the trees

They are more vulnerable than we realize

Broken tree branch
This gash was left after a huge limb broke off a blue oak
recently. (Photos: Kathy Morrison)

It takes a long time for a mature tree to die.

Yet we've all seen it, maybe without noticing the symptoms. The canopy grows sparse, or it starts dropping leaves and twigs at the wrong time of year, or there are holes all over the trunk. Years may go by before a windstorm blows it over. With the shade in that area now gone, the plants nearby are affected, and maybe the character of the site changes.

Trees are easily taken for granted.

I was reminded of this earlier in the week when I strolled over to our neighborhood park. I hadn't been in awhile, and I always enjoy seeing the changes that fall brings. Also, a flock of magpies lives there, and the birds are amusing to watch.

This park has been part of my landscape for nearly 25 years -- I've photographed most of the trees at one time or another -- so it was a bit of a shock to see a giant wound on my favorite blue oak. This tree stands probably 50 feet tall, just to the side of a small park building that formerly was a restroom and now is a utility room for the park district. A small muddy creek runs nearby about 10 feet away.

Blue oak before branch broke
Here's what the full-size blue oak looked like in January 2018.

The tree had recently lost its leader, its largest vertical limb, probably in the windstorm that blew through Oct. 26. About half the canopy was gone. Chunks of the giant branch still were on the crushed roof of the utility building. Parks district workers clearly had a big job just removing the limb from where it fell-- more cross-sections littered the ground nearby. The rounds were so big -- roughly 24 inches across -- they could have been mistaken for parts of a tree trunk.

Blue oaks ( Quercus douglasii ) are tough native trees. In the book "Oaks of California" (Cachuma Press), the authors note, "Although other oaks are resistant to drought, few of them combine all the mechanisms of opportunism, conservation, tolerance and resiliency that are known in blue oak." The tree also is one of the "Shady Eighty," trees recommended by the Sacramento Tree Foundation. This particular specimen undoubtably was growing here long before the neighborhood was built in the 1960s.

So why did this giant lose such a big section at this time?

Tree after branch broke
And here it is earlier this week.

The best clue is in those huge cross-sections of limb, and in the gash on the side of the tree. There were dime-size holes through the center (the pith and heartwood) of the rounds, and some of them were not fresh. The broken bit of branch still attached to the tree shows holes and rot.

This likely is evidence of borer insects, which years ago sensed a stressed tree and made this oak their home. Clearwing moths are among the insects whose larvae leave dime-size tunnels in trees, but it could have been another pest. SacTree notes of the blue oak: "Wood and root rots occur, borers and chewing insects can also be a problem."

Whatever caused the branch to weaken and break, this tree may not survive the injury. The remaining canopy, with the exception of one other smaller branch, still sported the tree's distinctive blue-green leaves. But since the tree stands next to a public walkway, it may pose too much of a liability to remain where it's grown for so many years. If it goes, I will miss it. Its fate also serves as an excellent reminder to care for our trees, before we're forced to notice them.

If you have questions about caring for any trees,  not just oaks, the Sacramento Tree Foundation is an excellent source of information:


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For week of Dec. 10:

Take advantage of these dry but crisp conditions. It’s time to get out the rake!

* Rake leaves away from storm drains and keep gutters clear.

* Fallen leaves can be used for mulch and compost. Chop up large leaves with a couple of passes with a lawn mower.

* Prune non-flowering trees and shrubs while they’re dormant. Without their foliage, trees are easier to prune.

* Rake and remove dead leaves and stems from dormant perennials.

* Make sure to take frost precautions with new transplants and sensitive plants. Mulch, water and cover tender plants in the late afternoon to retain warmth.

* Succulent plants are at particular risk if temperatures drop below freezing. Don’t water succulents before frost; cover instead. Use cloth sheets, not plastic. Make sure to remove coverings during the day.

* Clean and sharpen garden tools before storing for the winter.

* Brighten the holidays with winter bloomers such as poinsettias, amaryllis, calendulas, Iceland poppies, pansies and primroses.

* Keep poinsettias in a sunny, warm location. Water thoroughly. After the holidays, feed your plants monthly so they'll bloom again next December.

* Just because it rained doesn't mean every plant got watered. Give a drink to plants that the rain didn't reach, such as under eaves or under evergreen trees. Also, well-watered plants hold up better to frost than thirsty plants.

* Plant garlic (December's the last chance -- the ground is getting cold!) and onions for harvest in summer.

* Bare-root season begins. Plant bare-root berries, kiwifruit, grapes, artichokes, horseradish and rhubarb. Beware of soggy soil. It can rot bare-root plants.

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