En EspaŅol
Share

Ask Mr. Smarty Plants

Mr. Smarty Plants - Brown dead spots on arborvitae in Hillsboro OR

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
    
 
See a list of all Smarty Plants questions
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.

Need help with plant identification, visit the plant identification page.
 
rate this answer
Not Yet Rated

Monday - October 12, 2009

From: Hillsboro, OR
Region: Northwest
Topic: Diseases and Disorders
Title: Brown dead spots on arborvitae in Hillsboro OR
Answered by: Barbara Medford

QUESTION:

Hello. I live in Hillsboro, OR and have several mature arborvitae as a privacy screen in my backyard. They are on our side of a black chainlink fence separating our yard from a drainage area maintained by the city. Early last week we noticed that there were dead patches on all of the trees in our surrounding area. They are dead patches and not "dying". Apart from these dead patches, the trees seem healthy. This is inter-species as it seems to have affected pines, deciduous, broadleaves, etc. At first we thought it was just an irresponsible pesticide/herbicide job, but the dead patches are becoming worse and more noticeable and cover quite a large area. It has affected the trees in our small backyard, all of the trees in the drainage area, and across the street from that. Is there anything you know of that could possibly cause this?

ANSWER:

Sadly, you may be right about herbicide damage. Land maintained by a public entity, such as a city or county, may be sprayed for weeds, often by sub-contractors. If this is done carelessly or by untrained operators, the slightest puff of wind or bad aim can damage or kill other plants around it. The first step you should take is to call the city office responsible for maintaining that drainage area, and inquire about what has been done there recently. Certainly, you want to go to the drainage area and see if damage appears in the grasses or weeds in that area. Another thing to think about when you contact the city is that indiscriminate spraying of herbicide or pesticide, especially in a drainage area, can result in those poisons entering lakes in the area and, eventually, your glass of water.

Since this appears to be affecting more than one species of plant, if you eliminate the possibility of herbicide, we would recommend you contact the Oregon State University Extension Office for Washington County.  If this is happening in your neighborhood, it is happening in others and the Extension people are closer to the problem, and may be able to help you find a solution. 

 

More Diseases and Disorders Questions

Leaves turning brown in Fredonia KS
June 16, 2009 - Leaves turning brown.
view the full question and answer

Should I use wound paint when pruning my live oak tree?
February 04, 2010 - When trimming live oak branches, is it best to coat the wound on the tree? I have been doing this but have recently heard that it can actually be bad for the tree.
view the full question and answer

Controlling nematodes on lantana from San Antonio
September 19, 2012 - Can anything be done to "fix" root knot nematode on older lantana. Next to other lantana. Pull them out or try organic fix?
view the full question and answer

Damage to native elm in Texas
August 20, 2008 - We had a major landscape renovation done over the winter. One of the trees, an elm about 10 yrs old, remained in the bed although plants around it were removed. The tree has suddenly started turning...
view the full question and answer

Diseased non-native red tip photinias from Richmond VA
April 08, 2014 - Our red tip trees have a while substance on the bark at the base of each tree..look like some kind of fungus or mold, but we don't know how to get rid of it. Please help.
view the full question and answer

Smarty Plants's Facebook profile Support the Wildflower Center by Donating Online or Becoming a Member today.

Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP
© 2014 Lady Bird Johnson Wildflower Center