I am going to change queens of hives actually with chalkbrood and would appreciate some info about possible treatments ( against chalkbrood) to be applied before or after changing queens.
many thanks for your help
I used to get chalkbrood in small quantities, but since I started using Thymol (which is also a fungicide) for varroa control I haven't seen it at all. I only use it in May-June and September-October when the temperature is unlikely to go too high, as some people have reported problems with bees absconding when it's been used in hot weather.
On another tack, I remember reading that chalkbrood became a lot commoner in the States after TM came into widespread use as a prophylactic. I wonder if this isn't a case of the natural bacterial flora in the hive being disturbed by the antibiotic? I don't know whether you use the stuff in France or not; here in the UK it's only used under specific conditions, and never as far as I know as a prophylactic.