# Oxalic Acid Treatments for Fall



## Stephenpbird (May 22, 2011)

Wait for the brood less period, and one treatment vaporize or dribble is recommended.


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## enjambres (Jun 30, 2013)

Waiting for the broodless period is fine if you otherwise have control of the mites. 

If you are already at the thresholds for your area, then treat now rather waiting - and allowing further damage to occur to your winter bees.

According to SNL the current regimen is 3 vaporizations on 7 day intervals. In practice I found that I needed four to get the job done. Last year the recommendation was 4 treatments, on five day intervals. OAV does NOT kill mites under the cappings, which is why you need multiple treatments to zap them as they cycle out of cells.

I also do the single-shot, broodless period treatment in mid/late December to clean up any re-infestations that have occurred during the late fall, to give the bees a nearly mite-free winter, and to protect the earliest brood that's raised before re-infestation can occur once flying weather resumes. This works in my very-cold winter area, with its four to five month flightless period. YMMV.

I am not really confident about the number of treatments/periodicity currently recommended. But that is what it is right now.

Enj.


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## crofter (May 5, 2011)

There may be _some_ negative effects from using extra oxalic acid vaporization treatments but I think that is a far better risk than waiting till the bees quit brooding. note; oxalic _dribble_ treatment is definitely not recommended for repeat treatments.


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## Bob J (Feb 25, 2013)

For my hives I treated (OAV) 5 times in August at 5 day intervals..... All except the last treatment had a significant mite drop.... Assume it was due to mites protected under cap emerging.... Had no mites on the bottom board up until two weeks ago when several of my hives started to have a number of mites show up on the bottom board so treated again... Am pretty sure I dove a stake in the heart of the little buggers back in August but there are several other hives in the area so am thinking they may have hitched a ride with either robbers or drifting bees.... Am waiting until I am sure they are fully broodless in December and then will do at least one more just to make sure they are good going into winter unless I start to see them showing up significantly on the bottom board sooner....

The main thing I am learning is to be ever vigilant with Varroa.... Nice to have a treatment that poses little or no risk to the queen and is not ambient temperature dependent..... ;- )


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## zhiv9 (Aug 3, 2012)

OA is really only effective when there is no brood present. Another treatment should be used late summer/early fall to protect the winter bees. OA is a good a cleanup when they are broodless. 1 treatment for dribble and 1 or 2 for OAV. As Frank said, more than 1 dribble treatment can do real damage to the colony.


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## crofter (May 5, 2011)

Well zhiv9 I think that is overstated. The OAV treatment is being 90% or so effective on all the phoretic mites in the hive. I think it is considered to have a lasting treatment effect for a number of days beyond the instant of the treatment. Treat again to have the treating effect present as the remaining mites emerge from cappings. After three or four treatments no more mites are around to jump into 8 day cells. 8 day cells are they only window of reinfection and the phoretic mites are very susceptible to the action of the OA vapor while they are waiting to jump in or when they climb out!


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## zhiv9 (Aug 3, 2012)

The theory is good, but there just really isn't enough time after you pull honey in our area. 90% of phoretic mites at a time or year when the bee population is dropping and the mite population is rising isn't good enough. Even a single strip MAQS that kills around 60% of all mites, really just knocks them back for a couple of weeks. After that they are right back to where they were before. OA is a useful tool, but it has its limitations. Perhaps further research and development will lead to a slow release product that is more effective as an early fall treatment.


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## snl (Nov 20, 2009)

JMHammond said:


> Is there a recommended frequency for fall oxalic acid treatments?


One treatment in the fall if your hives are under control mitewise. Wait until the hive is at it's lowest brood point...........


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## Rusty Hills Farm (Mar 24, 2010)

crofter said:


> note; oxalic _dribble_ treatment is definitely not recommended for repeat treatments.


This time of year, that's very true. However, Randy Oliver's latest update on OAD suggests multiple treatments midsummer to be effective and not significantly damaging. Haven't tried it myself, but I AM considering a 3-4 hive test for next season.

HTH

Rusty


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## HillBilly2 (Jul 26, 2015)

I'll ask here instead of opening a new thread as it is related. Got my two hives built up pretty good, two deeps, pretty heavy, the cluster spans 6 frames or so. I treated with MAQS in August, I want to do an OA dribble on a warm day in December. Can't budget a vaporizer right now. Can I open the top and dribble the appropriate amount thru the seams, or do I need to split the hive and do each box separately? Running 10 frames in both boxes........Thanks!


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## snl (Nov 20, 2009)

crofter said:


> There may be _some_ negative effects from using extra oxalic acid vaporization treatments ......


Other than the time involved, haven't found any yet.


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## zhiv9 (Aug 3, 2012)

HillBilly2 said:


> I'll ask here instead of opening a new thread as it is related. Got my two hives built up pretty good, two deeps, pretty heavy, the cluster spans 6 frames or so. I treated with MAQS in August, I want to do an OA dribble on a warm day in December. Can't budget a vaporizer right now. Can I open the top and dribble the appropriate amount thru the seams, or do I need to split the hive and do each box separately? Running 10 frames in both boxes........Thanks!


You need to split the hive and do each box. Instructions here: http://www.ontariobee.com/sites/ontariobee.com/files/document/OA Protocol 2015.pdf


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## crofter (May 5, 2011)

snl said:


> Other than the time involved, haven't found any yet.


snl

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Default Re: Oxalic Acid Treatments for Fall

Quote Originally Posted by crofter View Post
There may be some negative effects from using extra oxalic acid vaporization treatments ......
Other than the time involved, haven't found any yet. 

snl,  I am just quibbling here; you clipped my statement and then quoted it. 

Notice that I put "some" in italics since some people on the "microflora idea" will insist that any thing you put in a hive to kill mites with, will have *some*, negative effects. That was by way of disclaimer! 

I have not seen any negative effects in hives I have treated either, though I have never needed to go beyond 4 times. If they needed more they would certainly get it.

As zhive9 points out correctly, if you wait till very late in the fall to do mite treatments you may run out of time. Looking at things from the angle of raising wintering bees though, that would compromise almost any treatment method. August is the month to get a handle on mites!


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