Why arborvitae die

Growing to 15 feet tall with a 5-foot spread in U. Department of Agriculture plant hardiness zones 4 to 8, Emerald Green arborvitae maintains a columnar form with a 3- to 4-foot spread. Billowy needled sprays give the plant a lush, somewhat informal appearance and medium texture in an evergreen tapestry. But when brown arborvitae dead spots appear, it's time to explore a little deeper to determine the cause and choose the proper treatment. Larvae feed on the needles throughout winter, causing foliage to yellow and turn brown.

The green color is generally restored during the growing season. Webs and cocoons on arborvitae, with silvery tan moths flying out when you shake branches, are evidence of the presence of this insect pest.

The University of California Statewide IPM Program recommends controlling tipminers by applying a systemic insecticide, such as one that contains the ingredient imidacloprid in mid to late winter.

Not the best plant for climates prone to drought, an arborvitae tree can die if allowed to dry out completely for only one day. So make sure that yours receives the equivalent of at least 1 inch of water per week via rainfall or an irrigation system. If you do not have an irrigation system, you can apply water via a water bag made especially for trees and shrubs or use two 5-gallon buckets with a tiny hole drilled in the base of each.

If you set those buckets on either side of your arborvitae, the water should drain out slowly enough to wet the soil without running off. Keep in mind, though, that over-watering can cause root rot, which also could result in browning foliage—especially if you planted the tree too deep. However, if that foliage seems to be shriveling, the problem is probably a burn instead.

That can result from a variety of issues, including extreme cold or too much sun, either of which can dry out the visible part of the plant while its roots still are too frozen to replace the moisture lost.

To prevent such desiccation, water your shrubs in late autumn before freezing temperatures set in, mulching them with about 3 inches of shredded bark. You also can protect them over winter with a burlap screen , which surrounds them on all sides, or with a burlap wrap. To help your trees try to create well-drained soil around them. With trees that are 30 years old that can be a challenge.

Adding organic material as mulch around the trees, but not next to the trunk will help add organic matter to the soil which helps with drainage. A mulch of inches will also help conserve moisture and moderate soil temperature, which can really help in hot dry conditions. Ask Extension. Dying arborvitae They were awesome beginning this summer. I can't see any bugs.

They are fifteen feet tall at least and pushing thirty years old. I don't want the others to die. Thanks for the quick response. I did have a expert trim my other half of the yard arborvitae. In June, all were watered well and did fine until Sept.. Who knows!