Arpivida turning brown and shedding needles.
We have an 8-9 foot Arpivida and once segment of the plan has turned brown and looks like it is dying. Can you help me figure out how to treat the plant? See the attached picture and info below. The plan is 12 years old We noticed the issue 5 days ago. Full sun, except for later afternoon. No known soil problems. No pesticide applications have been made directly to this plant, however the lawn was treated 4 weeks ago by NaturaLawn. Frank Walker
Winter injury is still showing up belatedly on evergreens as they are stressed more and more by high temperatures. When injury is only on one side of the plant, it can be an indicator that winter sun patterns played a part. If it is winter injury, entire dead branches can be pruned out, but certain the branch is really dead before removing it. Otherwise, it should put out new growth at the tips during the growing season.
If a herbicide was applied only along one side of the tree (the dead side) you may want to find out what was applied. Some lawn herbicides will down through the soil and kill roots beneath.
Also, check the branches for evidence of the new invasive insect, the Japanese Cedar long-horned beetle, especially if you start seeing similar damage on other arborvitae. Here's the info: http://extension.umd.edu/hgic/invasives/japanese-cedar-longhorned-beetle