Re: Negative Nosema
I would either go ahead and use the Fumidil-b or sample the yard again. I had two yards sampled last year and one came back "No Diseaes Found" and the other came back 2.5million spores per bee. They were three miles apart and both had been on the same semi, in the same holding yards and both had been in apple pollination. I am suspicious.
This year, two yards sampled, both negative for nosema.
I don't use fumadil, but if I were using it, I would use it on all of my colonies. Especially if some showed nosema and some didn't.
Squeak Creek Apiaries