Question
QUESTION: Will this product harm arborvitae trees if used in close proximity to the trees.  Late 2007 we planted 23 trees on our property line using oak chip mulch for ground cover, this spring the neighbors weeds are out of control coming into the mulch and nearing the base of our arborvitae.  We have tried pulling the weeds, but they continue to come back.  If mixed properly will the spectracide Weed Stop harm the aborvatie

ANSWER: This is not a good product to spray around trees since it contains mixtures of 2,4-D, and dicamba herbicides. Both of these herbicides will kill trees either by getting the solution on the foliage or by root up take from the spray.
It would be better to spray a herbicide called Roundup under the trees. Roundup will kill any green plant it is sprayed on but is safe around trees as long as you do not get it on the foliage. It will kill all the broad leaf weed and also grass that can get under the trees. Roundup will be absorbed by the plant and transported to the roots killing the plant but no harming the trees. It is widely used by landscape folks around shrubs.

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QUESTION: Thank you for responding. Thank goodness we waited for a response. We do have a couple of follow up questions.  We have seen two types of Round Up, - Roundup Kill Weeds & Grass and Round Up Kill & Prevent weeds and grass, what would you recommend for our application?  Next question what fertilizer should we use for the arborvitae?  They are 5 ft in height planted Oct 2007.  There are some brown spots appearing on areas in the trees, last year before winter 07 and again in March 08 we applied a Steins Garden Center for evergreens 32-10-10, supposedly a generic  for brand name miracle gro. Is this the correct product to use?  If it is how often should we fertilize?  Looking forward to your reply, thank you for your earlier prompt response.  Have a great day!

Answer
These products are ready to Use and the Prevent one contains an additional herbicide that can be absorbed by the roots so i would not use it. Both products will do the job.
Conifers need very little fertilizer so once a year is enough. The generic "hollytone" type fertilizer for evergreens is good.