Oregon State University Extension Service

How true is the Fox News story about dying trees in Lane County?

dead tree in a field

Both evergreen and deciduous trees have been suffering from drought conditions over the 2015-2018 summers. Dead trees you notice this summer likely died last summer or fall and didn't finish drying out until this summer. The main driver of this mortality is the drought conditions. Longer periods through the summer without rain in addition to multiple weeks in a row with over 90 degree weather is really difficult on the tubes in the trees that bring water from the roots into the leaves. Under the right conditions, this stress alone can kill the trees. Insects in this case are secondary. They are not driving the mortality of these trees. The beetles can "sense" the stress these trees are under and because their defense systems are weakened by the drought then they cannot fight off the insects. The trees are then not able to handle both drought and the insect attack together and the tree dies. So, insects are part of the story, but they aren't the reason for the dying trees. 

Trees that are watered in lawns are likely dying because of the way lawns are watered. More water over shorter periods of time doesn't allow the water to get deep into the soil where the tree roots are and most of the water gets taken up by the grass roots. Trees need watering that is little water over extended periods of time so that the water gets deep in the soil and there is enough to feed both the grass and the trees.

Source URL: https://extension.oregonstate.edu/forests/health-managment/how-true-fox-news-story-about-dying-trees-lane-county