Question
I purchased and planted 25 one gallon size, emerald green arborvitae shrubs, the first week in April of 2011.
The side of home where they are planted is exposed to sun until mid afternoon. Until 10 days ago all the shrubs were green without any brown spots and were growing as they should.
It is hot here the past 7-8 weeks, near to 100F, however it does not appear all those weeks that my shrubs are under stress or such.

One week ago, all my shrubs started getting brown spots towards the tip of all branches, on every side, side exposed to sun and side in shade. I did not changed the time or way how I water my shrubs (very early in the morning twice a week).

My neighbors driveway is two feet away from my shrubs. They put three weeks ago a new layer of painted concrete surface on their driveway. Two weeks ago they finished it with a final coat, a very  strong chemical, some type of acid. Temperature that day was near 100F and that strong chemical odor was all day evaporating from their driveway, and it was burning my eyes to stay near by, it was hard to breathe.

4-6 days after that all my shrubs start have those brown spots, all over but mostly on side where they facing my neighbors driveway.

Is it possible that chemical used on their driveway burned my shrubs or is it just coincidence that all that happened at the same time?

I have had emerald green arborvitae in the past in other homes in Oklahoma and in very similar temperature condition and they seemed to be fine  and grew well just like those 25 did until  10 days ago.

Please help me understand what happened to my shrubs and what can I do if anything at this point.
Thanks.

Answer
Lydia:
Your description does not sound like a bonafide contagious disease. I suppose there might be a possibility of injury here or there could be a coincidence. It would be helpful to determine what the materials were that were used nearby and if they could be harmful.

Probably best to arrange for someone qualified to examine your plants on site and a have history of events.  Suggest contacting your local county Extension office to arrange such a visit.  This is a good place to start.  Every county has such an office, usually located in the courthouse building. You can also inquire about this at your local nursery/garden center. Be sure to take pictures if you intend to seek any kind of judgement/compensation etc.

Sorry, I am not much help here. Again, I would suggest getting the opinion of someone who can make a "house call" to see your plants in person.

Regards
Steve