For Release October 5, 1999

AGRI-VIEWS
by Chuck Otte, Geary County Extension Agent

When a tree is called an evergreen, many people think that it holds on to it’s leaves (needles) forever. This isn’t quite right. An evergreen simply indicates that it does not shed all of it’s leaves in the fall. If you take a little time to stick your head inside a pine or spruce tree, you’ll find a lot of bare branches. Those needles had to go somewhere, they didn’t just disappear into thin air!

Take a look around underneath an evergreen. You’ll find old fallen needles, often a lot of them. The truth is that evergreens usually only hold their needles two to four years. If the growing conditions are good and a tree is putting on a lot of growth the tree may only hold needles for two years. If a tree is older and growth is slower, it may hold needles for four or more years. But eventually those needles will become old and inefficient and the tree will shed them.

Needle shed occurs in a variety of ways. As needles become old, damaged or ineffective they will be sealed off by the tree and may drop. This can occur anytime of the year. This tends to occur without much notice unless it is an entire branch at a time that is injured and dropping needles. What becomes more obvious is when we have seasonal needle shed. Often, in the late summer or fall, a pine tree will shed all of it’s oldest needles at once. The needles falling themselves are not so noticeable. What is noticeable is the yellow, often bright yellow, color they all turn for a couple weeks before they fall.

There is a lot of seasonal needle drop occurring right now in Scots and Austrian Pines. It may be occurring in other evergreens, but I’ve noticed it most in these two species. Seeing a lot of yellow, dead or dying needles can be quite discomforting to a homeowner. Here are a few ways to tell if you are seeing seasonal needle drop or something that is a real problem.

Are the needles yellow (or turning yellow) or are they brown or some other unnatural color? If they are turning a bright yellow or even a dull yellow then this is probably seasonal needle drop. If they are turning some other color then cause of death is probably something else.

Are the needles that are changing color mostly on the "inside" of the tree or do the dying needles extend clear out to the tips of the branches? Seasonal needle drop is only going to affect the oldest needles that are located nearest the center of the tree. The needles affect by seasonal needle drop will also be fairly will distributed throughout the interior of the tree. If you have branches that have dead and dying needles clear out to the ends of the branches, especially the newest tips, then you have some other problems that we need to discuss.

Are the needles that are changing color and dying staying on the tree or falling off? With seasonal needle drop, the needles will start to fall off or be easily knocked off after they turn yellow. Look on the tree branches and ground to see if there are a lot of fallen needles. If the needles turn color and stay on the tree, then the tree has other problems.

There are several diseases, especially of pine trees, that can cause dead needles or an entire dead tree. There are numerous environmental conditions that can cause evergreens to turn color and loose foliage. But seasonal needle drop is normal, nothing to worry about, and easy to diagnose with the tips that I just gave you.

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