I suppose that golfspyko is good to answer the question. He lives in Salt Lake City and according that there should not exist chalk brood.
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I'm a long ways from the lake. I've sorta equated chalkbrood with dampness and or shade. I've taken to placeing my hives in full sun whenever I can, and I haven't had any chalkbrood for quite a while. Maybe it's the queens, maybe the heat, maybe just luck. I can't prove it, but I think the hot summer sun slows down the mites some too. It's harder on me workin them in heat with no shade, but I've decided that I'm old enough to slow down or even take a break if I need one.
I'm guessing pH would have more to do with it:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11767561&dopt=Abstract
Syrup has a high pH (low acidity), while honey has a low pH (high acidity).
Using MB's notation then it would compute that overfeeding bees could induce Chalklbrood, especially in shaded areas. It's worth considering.