I would add a couple of comments to this if I may. Firstly the VMD only licence products to be used in sublimation once per year on bees. I quote below the personal email I have from Professor Ratnieks that two treatments are best - seperate email said 7 - 10 days apart.
Secondly running an Enhanced Sentinel Apiary I get three inspections a year, to date they have never requested to look at treatment cards. Their interest and time is spent on disease control i.e. EFA/AFB/Small hive beetle. A full day is about 15 - 20 hives inspected normally. Even when my honey is sent away for sampling they are not checking for Oxalic Acid residue.
I could not of course comment on whether I am prepared to pay exorbitant, rip off, outrageous prices for added rubbish or use the strictly illegal pure stuff.
Dear David
We have done research to show that single and double applications of oxalic acid, 2.25g, by sublimation in brood less hives cause no harm to bees or colonies. The research we do and the advice we give is not for any one country but general, and beekeepers can adapt this to their own situation. It is a pity that the regs for VMD in UK only permit a single application per year by sublimation, when two applications can be done with no harm to the colony and increases the varroa kill to 99.6%, and suggests that the regs could usefully be changed, in light of the scientific evidence, to permit two or multiple applications. I will leave that for the powers that be to sort out.
best regards, Francis
[Firstly the VMD only licence products to be used in sublimation once per year on bees.]
Re the once a year, if a treatment is two doses would this be classed as once a year