For Release June 13, 2004

Many Trees Suffering from Accumulated Stress

by Chuck Otte, Geary County Extension Agent

I sometimes find it easier to understand plants and their problems if you compare them to humans and their physical ailments. Take a middle aged human who has arteries that are slowly clogging up with plaque. As long as that person is going about their daily work they are okay. They are very used to the level of work, exertion and stress that they experience every day. But now, without any training or preparation, throw that person into a marathon or anything requiring extreme physical exertion. That person may not survive. The added stress required more of them than their body could provide.

Plants face stress too. The Kansas climate can be very stressful. Simply examine the daily high temperatures for the month of May. They were all over the board. And that was just in one month! Look at the extreme weather, particularly the summer weather, for the past four years. Think of last August when we had 12 days in a row of 100 degrees of higher and hot dry winds. The Kansas weather is brutal.

Now, into that climate, let's start introducing some plants that are not native to the Great Plains. These are plants whose leaves may not be able to reduce how fast water evaporates out of the leaf in really hot weather. Or it may be a plant whose root system is not very effective at scavenging water from soils. If that's the case, it doesn't matter how well you watered the plant, because the plant didn't have the rest of the required equipment to deal with these extremes.

One dry year or one hot year or one cold year may not be a real problem. The plant stresses, some internal damage occurs, but the next five years are much better and much of that damage is repaired. But let's lay four years, or more in some parts of the state, back to back to back. Suddenly you have damage occurring in one year that isn't fixed the next year. Not only is it not fixed, more damage is added to it. This is accumulated stress.

Accumulated stress shows up in many ways. A tree may leaf out and then suddenly all the leaves wilt and die simultaneously. The entire vascular system of the plant has been damaged to the point that when the water requirement of a full set of leaves hit it, it can't handle it. The system collapses and the tree is dead.

Or some branches may leaf out just fine this spring, but others don't. They may leaf out several weeks later, or they may in fact be totally dead. Foliage may get thinner and thinner for several years in a row. Then all a sudden the tree is growing a lot of new shoots directly off of large main branches or trunks. This is a classic sign of stress and often indicates that the tree won't live much longer. To complicate things further, once a tree starts to undergo stress, it becomes predisposed to other problems. Diseases start to move in that normally wouldn't be a problem. In some cases it's almost as if a flashing neon light goes on inviting insects of all kinds to come and take up residence.

All you can do at this point is try to ride it out and avoid any further stress on the plant. Even if the tree doesn't die, it may be damaged to the point that all you can do is remove it and replace it. We can't do anything about the weather. But we can make sure that we plant species that are adapted to our weather extremes, take care of them as best we can, and hope and pray that Mother Nature cooperates!


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