Brown spot - Arbor Vitae

Asked September 23, 2020, 6:19 PM EDT

Please see attached picture. My arbor vitae bush has a brown spot. Should I be concerned? What should I do? Thank you for your input.

Howard County Maryland

1 Response

Dense Arborvitae varieties like this can easily have stems bruised or broken by grabbing foliage to carry or move the plant during planting. If this was planted relatively recently (in the past few months) then this is likely what happened. Otherwise, it may be dieback related to minor root stress from under- or over-watering. (Arborvitae want to neither get very dry nor stay constantly wet.)

In either case, it should be trimmed out (all of the small branchlets with all-brown foliage) as it will not regrow in this spot. Surrounding foliage may eventually help to cover-up this spot as the plant ages, but due to its slower growth rate this will take several seasons. Since we have had patchy rain earlier this season and dry autumns in past years (like last year) we recommend continuing to monitor it for watering needs until we experience regular frosts. Here are some general tips for watering trees and shrubs: https://extension.umd.edu/hgic/topics/watering-trees-and-shrubs

Miri