Preen on pavers.
PAVERS ARE BEAUTIFUL BUT ALL KINDS OF WEEDS AND GRASS LOVE TO GROW IN THE CRACKS SINCE THEY ARE LAID IN A BED OF SAND. PREEN SWEPT INTO THE CRACKS WORKS WELL BUT NOW I AM STARTING AN APIARY. WILL THIS PRACTICE BE HARMFUL TO BEES? BEES DON'T EAT SAND SO I AM HOPEFUL THAT THIS IS A SAFE PRACTICE.
Carroll County Maryland
Preen is a preemergent herbicide that once watered in creates a barrier.
If bees don't visit there, we'd think they wouldn't be harmed, (unless you have solitary mining bees trying to nest there).
To be safe however, we suggest contacting the National Pesticide Information Center with your question, including the active ingredient on the label of your product as there are various Preen formulations. They have an 800- listing on their webpage here: http://npic.orst.edu/
You should also chat with your local beekeeping association, if you haven't already. They are here: http://www.carrollcountybeekeepers.org/