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Sunday, September 20, 2009

Help! My trees are turning brown!!

I really should know better by now. As a Master Gardener, I was trained long ago that conifers (such as pine, spruce and fir...) drop some of their needles on a regular basis. The trees generally don't shed needles every year, as deciduous or leafy trees do. Depending on the species of tree, most conifers usually lose their interior needles every two to five years.

But YIKES! Even knowing all of that, I still did a double-take and caught my breath when I saw one of my thirty-foot Ponderosa pines seem to change overnight. The crew in Tagawa's Nursery Department is hearing the same thing: "Help! My trees are turning brown!"

Tagawa's staff is quick to let these tree-loving folks know that they probably don't need help, and neither do their trees. This type of needle-shed is normal, and most likely there's no reason to use any insecticides or other chemicals. Let's take a closer look.

Like deciduous trees that drop their leaves every fall, healthy conifers put on new growth each year. The tree grows up and out, with clusters of new needles at the tips of the branches. But the trees won't keep these new needles forever.

Take my Ponderosa pine, for example. The needles that have just turned brown are the oldest needles..... three years old, to be exact. That's how often Ponderosas shed. The dying needles are on the inside of the tree, closest to the trunk. These old needles are now shaded out by the newer growth, and quite simply, the tree doesn't need them anymore. So with alarming suddenness, they fade to the color of straw and dry up. The first time we have a strong windstorm, they'll blow off, and the tree will look lush and healthy again.

But the change really does seem to happen overnight, or close to it. And it can be understandably alarming.

So how do you know if your conifer trees are going through a normal fall shed, or have a genuine problem? Here are some things to look for:

*** Normal needle shed will always be on the inside of the tree. It will
discolor those interior needles fairly evenly throughout the tree as
a whole... not just in one part of the tree.

*** Unless the tree has been stressed by drought or other conditions that
could have damaged the roots, normal needle shed will usually occur
in late summer or early fall. Serious stress issues could prompt a tree
to shed its needles earlier. It's the tree's way of calling "uncle" for the

*** If the tree is healthy, the new growth on the tips of the branches should be
supple, green and full, not brittle or discolored.

Trees that have been attacked by the dreaded mountain pine beetle have a different look. These doomed pines (pines only) will often show "pitch tubes" on the trunk.... white or pinkish popcorn-looking areas where the tree has tried to flush out the invading beetle.

Mountain pine beetles fly in late summer. Obvious signs that they've attacked a tree generally won't show up until the next year. I notice the dying trees most often in July, when the summer heat really kicks in and the tree's stored energy finally isn't enough. (It's genuinely amazing how long a sick or damaged tree can look "normal," just running on stored energy. )

A pine beetle attack will often give the entire tree an orangish or reddish cast as it fades and dies. There are ways to protect your most valued pines against this destructive insect. Talk to the folks in Tagawa's Nursery Department or Dick's Corner for details.

But don't mistake a normal late-summer needle shed on your conifers for an invasion of anything harmful. And by all means, don't automatically reach for the insecticide with the mistaken notion that you "just need to spray something." Odds are, you don't.

And remember that with all of our spring rain this year, conifers have put on a lot of new growth. That growth that will most likely have us doing a double-take and catching our breath when it's time for this year's needles to shed a few seasons down the road.

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