# Oxalic acid drench concentration



## sharpdog (Jun 6, 2012)

I have more mites this year than most, so I have increased the potentency of the oxalic acid dribble I used this fall. Using Randy Olivers chart, I used slightly less than the Hot treatment. I am hoping its not too strong. Have any of you guys experimented with oxalic concentrations and efficacy? I used 55g/litre of 1:1 syrup. Medivet website recommends the weak treatment of 35g/litre. Any thoughts?

http://scientificbeekeeping.com/oxalic-acid-treatment-table/

Im surprised Randy doesnt provide a suggested concentration. 

Luke


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## jean-marc (Jan 13, 2005)

I would have stuck with the 35 g/litre. Liquid oxalic acid is a bit rough on bees. We are in for a long winter (my crystal ball) and the bees inability to fly and defecate make it that much harder on them. I might try a hotter application when the bees are able to fly.

Any thoughts as to why your mite counts are up? I am thinking there was a less than stellar performance of a not so distant Apivar application.

Any reasons as to your second guessing yourself? I do it all the time, lol, it is par for the business. There are far too many things that can and do go wrong in this business.

Jean-Marc


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## Ian (Jan 16, 2003)

The guys here in the provincial extensions office found the increased OA concentration in the Drench dosage did not increase efficacy. Stick with the recommended measure


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## sharpdog (Jun 6, 2012)

I treated with thymovar spring of 2015 and had zero mite count washes almost all year last year. I dribbled the medium oxalic treatment as usual in fall. Spring 2016 I used Thymovar again, but already in June my loads were 1-2% with a few samples even higher. I found more mites in brood and saw many more with my eyes while searching for queens. I considered MAQS, but feared the loss of queens. I had a record honey crop, but now I need to make sure I knock these mites back. I havent used synthetic miteicides in three years, but this spring I am considering using apivar again, but I have heard a several stories of suspected resistance.


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## jean-marc (Jan 13, 2005)

MAQS does kill queens for sure, we tried to use that to our advantage. We had a bunch of queens in our back pocket after the application. They knockoff the older queens. 
I guess we are hearing the same suspected mite resistance to Apivar. Are your bees broodless? I think it would be a bit early for that, but if levels are high, I guess you need to do something. What kind of levels are you seeing?

Jean-Marc


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## sharpdog (Jun 6, 2012)

3-10% 
Some brood but very little.


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## jean-marc (Jan 13, 2005)

Ok. It is a little high but as long as you are not seeing damaged bees the dribble will knock them right back. All the mites are phoretic now so it appears high but a good application of oxalic and Bob's your uncle. 

Are the bees in doubles? If so did you crack them to drizzle the bees in the bottom box?
Our bees in Alberta are mostly broodless now. 10% have larva, the rest a little bit of capped brood that will soon hatch and that will be it for this season. We will bring them home in 2 weeks. I want them to go from winter in Alberta to winter here. Temperatures are cooling off and the rains are about to begin in earnest.

Jean-Marc


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## zhiv9 (Aug 3, 2012)

I have always followed these instructions at 35g/l: http://www.ontariobee.com/sites/ontariobee.com/files/document/OA Protocol 2015.pdf

If you are concerned about queen loss with MAQS, you could try 2 one-strip treatments 10-14 days apart. Not as effective as a two strip treatment, but easier on queens.


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## sharpdog (Jun 6, 2012)

I am pretty sure they will come around, as the populations are still strong. They are down to singles which is how I have always wintered them indoors. As for winter... its here. We got 8" of snow on the weekend. Thanks for the input Jean-Marc.


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## ApricotApiaries (Sep 21, 2014)

What are the day and night temperatures like when you guys are dribbling up there in Canada?


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## jean-marc (Jan 13, 2005)

We are daytime highs around 55 F nightime 40 F. I am in the south and on the coast... so the banana belt of Canada sorta speaking. Where Sharpdog is likely freezing nightime tempseratures, 25 or so and a daytime high around 40. Generally speaking on the prairies when I grew up we expected snow to stick around until spring after Halloween. Before that not usually but it could. I would think the bees on the prairies are broodless now. The ones that we brought backfrom the prairies 2 weeks ago have capped brood now. They fired up again in what the bees thought were greener pastures. They will stay broody for another month, the new queens that I made in the last increase a bit longer. Some years they do not shut down.

Jean-Marc


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## zhiv9 (Aug 3, 2012)

ApricotApiaries said:


> What are the day and night temperatures like when you guys are dribbling up there in Canada?


Ideally we want them clustered and broodless. Highs of 50F or cooler. Lows in the 32-40F range. Can get away with a little warmer temps by dribbling in the early morning or evening or on an overcast day.


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## ApricotApiaries (Sep 21, 2014)

Thanks, That's about what I thought. I am finishing up my fall feeding/combining in the next couple weeks and would like to do a final cleanup of mites. 
I would like to play with a fall dribble a little bit but there is something about dribbling liquid and getting my bees all wet at this time of the year that I have trouble wrapping my head around. Right now I have highs in the 60's and lows in the 30's and 40's. The bees still have a little brood but not much.


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## jean-marc (Jan 13, 2005)

Bees are pretty tough. The maximum amount of oxalic ais in sugar solution that can be given to a double is 50 ml, that is a little bit less than 2 shots of JD or whatever your poison is. On singles 5 ml perseam of bees, that is a teaspoon. Your bees won't get all wet. 5-10 minutes after application all syrup should be gone. The cluster might open a bit to pass the syrup around, that's it. It's a nice cleanup to varroa when bees are broodless, cheap, fairly quick. The big drawback is when the bees are confined all winter with the oxalic toxins in their body. Come spring those bees are slower to get going. I think, although I do not know this for sure, in your area and mine bees will have an opportunity to fly within a few days or at the most 1 month after treatment. At that point they will be able to void some of those oxalic toxins from their bodies. This could translate into normal spring development. 

I have only used liquid oxalic once. It was fairly quick. I think it worked ok. Some guys who have used liquid oxalic are a little relactant to use the method because of harhness of the drench method on the bees.

Jean-Marc


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