blair, chalkbrood is a real pita. it is a fungus, the spores spread and really there is no treatment for it, or i thought so. bakers suggested apiguard or thymol. i was not aware of this, and have never used thymol to treat chalkbrood. googled it quick, and bee informed partnership claims that apiguard, thymol are active against chalkbrood, also mentions 'vitafeed green' and 'bee vital chalkbrood'.
link is here for the article:
beeinformed.org CHALKBROODi have not used any of these products for chalkbrood treatment so can't say how this would work.
if your colony is weak, it may get worse (not saying it will); not going to get all technical, but chalkbrood can really take a toll on a weaker hive. consider combining it with a stronger hive. moisture and cooler weather doesn't help, and sometimes there can be other stress factors. for example, weather, mites, lack of pollen, lack of nectar, a failing queen..........etc....could be anything that contributes to a colonies stress.
as bakers said, you could try boosting the population of the weak colony. the bees need to haul the larvae out and clean the cells up, (hygenic behavior) if they can't do this quickly, infection spreads. you may want to destroy combs if many mummies in cells. also, check everyday and clear the dead mummies off the landing board that the bees are hauling out.
how old is your queen and what breed of queen? you may also want to consider requeening.