They are more vulnerable than we realize
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.
Here's what the full-size blue oak looked like in January 2018.
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?
And here it is earlier this week.
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: sactree.org
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Dig In: Garden Checklist
For week of March 26:
Sacramento can expect another inch of rain from this latest storm. Leave the sprinklers off at least another week. Temps will dip down into the low 30s early in the week, so avoid planting tender seedlings (such as tomatoes). Concentrate on these tasks before or after this week’s rain:
* Fertilize roses, annual flowers and berries as spring growth begins to appear.
* Knock off aphids with a strong blast of water or some bug soap as soon as they appear.
* Pull weeds now! Don’t let them get started. Take a hoe and whack them as soon as they sprout.
* Prepare summer vegetable beds. Spade in compost and other amendments.
* Prune and fertilize spring-flowering shrubs after bloom.
* Feed camellias at the end of their bloom cycle. Pick up browned and fallen flowers to help corral blossom blight.
* Feed citrus trees, which are now in bloom and setting fruit.
To prevent sunburn and borer problems on young trees, paint the exposed portion of the trunk with diluted white latex (water-based) interior paint. Dilute the paint with an equal amount of cold water before application.
* Cut back and fertilize perennial herbs to encourage new growth.
* Seed and renovate the lawn (if you still have one). Feed cool-season grasses such as bent, blue, rye and fescue with a slow-release fertilizer. Check the irrigation system and perform maintenance. Make sure sprinkler heads are turned toward the lawn, not the sidewalk.
* In the vegetable garden, transplant lettuce and kale.
* Seed chard and beets directly into the ground.
* Plant summer bulbs, including gladiolus, tuberous begonias and callas. Also plant dahlia tubers.
* Shop for perennials. Many varieties are available in local nurseries and at plant events. They can be transplanted now while the weather remains relatively cool.
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