Privacy screen arbor shrinking annually

Asked August 19, 2019, 11:21 PM EDT

For the third year in a row during the month of August, I’ve watched my screen lose it’s northern-most end member. I haven’t watered that section this year (last 2 years I assumed it was over-watering and root-rot). Still seeing an annual loss on the northern-most end of the line.

Benton County Oregon

1 Response

Hello there. Arborvitae suffer from several diseases and have several insects that can impact them. What makes you think this is a root rot problem? This photo from a distance it is difficult to tell if there are symptoms in trees to the left that might indicate the start of a problem in trees closer to the dead one. Root rot is a common issue for these trees as is fungal and insect problems. Do these trees stand in water for a period of time during the winter? What do the roots look like on the trees that have been removed? Have you found and insects on them or any fungal spores? Seen any unexplained holes in the bark of removed trees?

When I look at this photo full screen size it seems to suggest some involvement of the ‘healthy’ trees is already beginning. These plants do need some summer water, so I am not sure withholding water is helping the situation. If this is an insect problem, it could be harming the remaining trees as insects attack stressed trees.

If there are some brown areas on branches of trees not yet dead, I suggest that you remove several pieces of them and bring them to the Master Gardener Information Desk in the Oregon State University Extension Office here in Benton County. They will be looking for evidence of fungal spores and for insects. Take some closer photos that show areas of the trees that are starting to brown and bring them with you as well as showing this photo. If you have winter photos showing water over the roots bring that photo or information in also. If you take out the tree that is currently dead a sampling of the roots would be great as well as some photos of the roots zone as it is being dug up.

The Extension office is located at 4077 SW Research Way, Corvallis. Office hours are 8 a.m.-5 p.m. Monday through Friday. It is a good idea to call first to ensure a MG is on duty as there are several questions that they will need to ask you to help them figure out what disease or critter is causing the problem with your trees. The phone number is 541-766-6750.