It’s not easy being evergreen

The heat and drought have been tough on trees especially the evergreens.

Spruce, fir and pines are not well adapted to local growing conditions. And a high stress year like this one has led to decline and death.

However, there are natural conditions that can look like the trees are dying but actually are not harmful. How can you tell the difference? Here are some tips to help you decide if your evergreen is dead or alive.

Evergreen trees are very different from deciduous trees. Deciduous trees drop their leaves every year in the fall. Evergreens do not. They hold on to their needles for three and four years before letting go.

This process is called natural needle drop. If the needles closer to the trunk are turning brown, yet the needles on the tips of the branches are still green, the tree is going through natural needle drop. This does not harm the health of the tree and is normal. Drought stress may increase the number of needles that drop, but there is nothing you need to do to stop or slow the process.

Natural needle drop is very different from branch die back. In many cases I am seeing all the needles on a branch turn off-color. This is not good. There are two possible reasons why this is happening.

In pines, this may be due to pine wilt nematode, a non-controllable fatal disease that is found primarily on Scots pine. The other possible cause is heat and drought stress. Evergreen trees are simply running out of water. Even with the little rain we have had recently, there is not enough soil moisture for these trees to survive.

To help determine the future of your tree, check to see if the branch with the browning needles is dead or alive. Use a sharp knife to scrape off a small area of the “bark” of the branch. There should be green tissue just under the bark. This green cambium layer is quite thin with the underlying woody tissue being white. If there is no green at all, the branch is dead.

Also check the ends of branches. Dry, brittle twigs are a sure sign that at least that part of the tree is dead. Dead branches should be removed. Major branch removal may destroy the overall look of the tree, making tree removal the only viable option.

At this stage of the game, the only thing you can do to help an ailing tree is concentrate on good watering. During dry weather (even this winter), water the trees to a depth of at least 10 inches. You can check the depth the water reaches by pushing a long screwdriver, metal rod or wooden dowel into the ground. It will stop when it reaches dry soil.

If the temperatures should turn hot and dry again, trees may need watering once a week. If we have a mild, dry winter, water the trees once a month when the temperatures are above freezing.


Bruce Chladny is horticulture agent at K-State Research and Extension-Douglas County. For more information, call him at 843-7058 from 8 a.m. to 5 p.m. weekdays.