If you are not interested, please just skip this message. Thanks.
Personally. I am interested because I used the drench method commercially at least ten or maybe twenty years ago, before it was respectable, and I know the guy who started it, AFAIK. The optimal concentration has been a big question mark as long as it has been in use. There are currently a number of studies going on and several conflicting recommendations out there. Moreover this could technically be construed as an off-label usage.
I haven't seen Keith's numbers, beyond what he posted below, or any documentation, so I would be glad to be pointed to them.
Maybe I'm wrong, but given the price of fumigillan, I should think most commercial beekeepers would be interested to know if they need to boost or lower the dose.
Anyhow, here is some correspondance with Steve Pernal, (Beaverlodge Research Station) which he says I can share. Some of you might want to contact him if you have information.
> I should have some data on the drench technique this spring as we used that as a treatment in fall trials (i.e. fall 2008). I have concerns about using a low volume syrup treatment in the fall as it may have less "staying power" in the hive over the winter.
> Based on our spring 2008 experiment using packages, where we evaluated 0.5, 1 and 2 x label doses, we saw no evidence of increased efficacy with increased dose. We applied fumagillin as icing sugar dustings, in pollen patties and in syrup. Basically all worked, perhaps with the exception of some delayed effciacy on some of the patty treatments.
> For N. ceranae, the Spanish recommend 4 applications of fumagillin, each application in 250 mL of syrup in a bag placed on the top bars. Each application contains 30 mg of active ingredient for a total of 120 mg of active ingredient applied per colony. They sugges this confers control for ceranae for six months.
> I don't have the answers yet, but I would predict we may have to get into a paradigm by which we may have to control in the spring and fall. The spring treatments will have the additional concern of not contaminating honey, which is why we have been looking at different application methods.
> I anticipate running fall and spring efficacy experiments for nosema for at least 2 to three more years. I would be very interested in knowing if there appears to be a treatment that is being informally adopted by beekeepers, so that I can include it as a comparative treatment in experiments.
> Randy Oliver will be at Medhat's IPM symposium in Feb. He may have some insight from the U.S. as well.
> Stephen F. Pernal, Ph.D.
> Research Scientist | Chercheur
> Beaverlodge Research Farm | Ferme de recherche de Beaverlodge
> Agriculture and Agri-Food Canada | Agriculture et Agroalimentaire Canada
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> Beaverlodge, AB T0H 0C0
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