This is an actual conversation that took place one late winter day at the nursery where I worked:

Caller:  Yes, I was wondering if you could answer a question for me.  I’m going to spray my plants, and the container says not to use it on arborvitaes, and I was wondering, “Why not arborvitaes?”  What will it do to them?

Me:  What are you spraying?  Is it dormant oil?

Caller:  It’s horticultural oil.

Me:  So, you’re spraying for insects?

Caller:  (Getting exasperated with me) I’m just, you know, I’m spraying my plants!  My boxwoods and yews and stuff, and I was wondering why I shouldn’t use it on arborvitaes.  I thought you guys would have had experience with this stuff.  Maybe you could ask one of your experts–not that you’re not an expert. . .

Me:  I guess I don’t understand why you’re spraying when there isn’t a problem.

Caller:  (Getting really exasperated with me now and ignoring my response) I’m thinking they’ll get burnt by it, that arborvitaes can’t handle this spray and will get their foliage burnt.