I wonder if this is another one of those situations that the answer would vary in different parts of the country. I don't know of anyone in this area that does a drench for Nosema. Everyone uses a medicated sugar syrup to treat in the fall. When the treatment is done this way, we don't have a problem with Nosema.
Jen, a few weeks ago I printed out the mixing and feeding instructions of Fumagilin-B from Medivet. Medivet recommends the following ratios for FALL treatments:
Water +Sugar =Syrup +Fumagilin B
1/2 Gal +8lbs. =1 gal + .18ounces or 1 rounded teaspoon
2 1/4 Gal +37lbs. = 5.2gal + .85 ounces or 24g bottle
For our purpose, I won't bother with the larger proportions. If needed readers can visit Medivet's web site.
www.medivet.ca/For 2 chamber colonies= 2 gallons of treated 2:1 sugar syrup (approximately 30,000 bees)
For 1 chamber colonies= 1 gallon of treated 2:1 sugar syrup (approximately 18,000 bees)
(Medivet is referring to double deeps or single deep hive bodies. )
Additional recommendations include:
Using a concentration of 2:1 sugar syrup for treatment.
For best results heat the water to 35-50C, remove from heat source, dissolve the Fumagilin B in water and then add the sugar.
To eradicate Nosema parasites, Fumagilin B
should be applied over several weeks.
Heavily infested colonies that will no longer take in syrup may be sprayed repeatedly, directly onto the bees, frame by frame, with 1:1 sugar syrup containing 2g of Fumagilin per 1 liter.