Oxalic Vapor

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cam bishop
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Oxalic Vapor

Unread post by cam bishop » October 22nd, 2011, 6:07 am

Since that is my primary method of mite control, I'm following your experience quite closely. I wonder if you wouldn't have had better results if you had completely closed the hives up for 5- 10 minutes. I use a much smaller and simpler vaporizer, run it for 2 minutes with the hive closed and get pretty good results. Haven't had a killing frost/freeze here and still have some brood in the hives. I will give them another shot of vapor when they are in cluster.
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Re: Oxalic Vapor

Unread post by Allen Dick » October 22nd, 2011, 9:25 am

I wonder if you wouldn't have had better results if you had completely closed the hives up for 5- 10 minutes.
I've been wondering about that. I think we will be able to figure that out when I treat again in a few weeks.

I have also considered adding two Apistan strips to the one hive which is in only two boxes and where the cluster is accessible without major surgery.
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Re: Oxalic Vapor

Unread post by cam bishop » October 22nd, 2011, 1:41 pm

That would give an interesting contrast of mite drops between methods.
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Re: Oxalic Vapor

Unread post by Allen Dick » October 22nd, 2011, 7:57 pm

I'm starting to think I overestimated the mite load, though.
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Re: Oxalic Vapor

Unread post by cam bishop » October 25th, 2011, 10:56 am

Seems like you got a pretty good kill. Wish I could afford one of those vaporizers. Seems like you might get much better distribution of the acid with the blowers. I've read that the acid vapor crystallizes very quickly in the hive, so closing it up may not be that important. I know in my hives I get a pretty good mite drop for about 5-7 days, then it tapers fast. I have pretty low counts [shaker method and drone monitoring] but don't want the mites to explode someday. I tried to get the cloud of vapor that Randy talks about on his web site but couldn't reproduce it... dissipated pretty quickly.
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Re: Oxalic Vapor

Unread post by Allen Dick » October 25th, 2011, 11:30 am

I think for a few hives, a person could increase distribution by using a compressed air tank and a blower fitting alongside the evaporator.

I doubt that it would make much difference, though, since the classic way to apply oxalic that is also quite effective is using the Varrox evaporator and it has no air assist.

Making two applications, some time apart is probably more important than getting an extra 1% or 2% on the first try.
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Re: Oxalic Vapor

Unread post by cam bishop » October 26th, 2011, 6:55 am

compressed air and blower is too complicated for me. I use the Varrox and get good results with it. I try to use it 3X a week to 10 days apart. Only going to get 2 treatments this year, too much rain and mud... I am having problems getting some hives out to their winter placements.
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Re: Oxalic Vapor

Unread post by Vance G » November 2nd, 2011, 7:17 pm

What do you think the mite levels are in hives 3,4 and 5 if the drop is still so high? I think I would have paniced and retreated by now.

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Re: Oxalic Vapor

Unread post by Allen Dick » November 2nd, 2011, 10:28 pm

I really don't know. For one thing, a significant part of the drop is young mites and for another, I think I may be looking closer and counting more carefully than most.

Also,the heaviest drops were right after the treatment and have been tapering off, as expected.

Jean-Pierre Chapleau uses natural drop of 24 mites a day around this time of year as a threshold of damage, and if we average the counts over time and over the hives, I am close to the limit, but not over. I'm under in four of the five and marginal in that one, and I don't know if we can again call this a "Natural Drop" yet.

The fact that there is brood complicates things, and only time will tell. We are dropping below freezing for days on end shortly, so that should be cutting the brood rearing back.

When brood rearing ceases and there is suddenly no new brood for the mites to go into, the number of phoretic mites triples. Phoretic mites are more vulnerable and die more easily and often than similar adult mites hidden in brood, so that may be why the increase in drop right about now, too.

The last thing is that the treatment equipment is not mine and so I have to treat when I can. I expect that I will sometime this coming week.

If I had some Apivar or Apistan, I would have tried it on a hive or two by now, just to see.

Image
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Re: Oxalic Vapor

Unread post by Vance G » November 3rd, 2011, 9:56 am

I think I will be hitting the hardware store and making one pretty shortly. Now you have not remarked on any aborted brood or number of dead bees so I am assuming that this treatment is not very damaging to the bees. I can't see much downside in doing a cleanup, just in case, when the bees are broodless. My bottom boards do not allow much room for sticky boards. I guess I could take white poster paper and grease it as you do and get a drop number.

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Re: Oxalic Vapor

Unread post by cam bishop » November 11th, 2011, 3:34 pm

I wonder if OA vapor kills tracheal mites too? I always thought it didn't but a local beek who uses it claims it does.
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Re: Oxalic Vapor

Unread post by Allen Dick » November 12th, 2011, 7:17 am

I don't know, but quite a few people seem to think it does affect tracheal mites.

I don't know if it gets to the mites inside the bees trachea, and I can't see how it would not, but it would definitely affect any mites outside the bees.

I'll have to keep asking that question.
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Re: Oxalic Vapor

Unread post by cam bishop » November 12th, 2011, 11:50 am

I looked for studies and couldn't find any.
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Re: Oxalic Vapor

Unread post by Allen Dick » November 16th, 2011, 7:55 am

I put the question the brains at BEE-L. Let's see what emerges.
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Re: Oxalic Vapor

Unread post by cam bishop » November 16th, 2011, 5:32 pm

I can't hazard a guess on the mite counts. However, this study has reaffirmed my confidence in the OA vapor treatment for mites. I try to use 3 treatments one week apart. This fall has been so warm that I'm still getting brood rearing and I'm sure it is going to cause me problems.Even my Carni's are raising brood. Bees are finding some pollen somewhere, not a lot. I guess I'll wait for a couple of cold weeks and then treat again. I'll also probably need to put pollen patties on early since they are using up their stored pollen. I have a friend in VA who reports that maples are blooming and bees are working them. Strange year down here.
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Re: Oxalic Vapor

Unread post by cam bishop » November 20th, 2011, 4:27 pm

I notice no response from Bee-L about trech mites. I also wonder about winter survival with OA vapor. I had 50% survival last winter and OA vapor is all I use for mites. It's also interesting about EPS hives/mites. Makes me wonder' about my nucs. Ordinarily I don"t worry about mites/nucs because of the brood break. However, I have not checked them for mites. Might be in for a big surprise.

I like the larger font on your web site... much easier on these old eyes.

You should put together a paper on this research. Not available anywhere else IMO. A lot of detail and good information. I'm very grateful.
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Re: Oxalic Vapor

Unread post by Allen Dick » November 20th, 2011, 5:31 pm

Thanks for the vote of confidence. I'm surprised at the lack of response.

Sadly, much of the research these days seems to be published with an eye on what others done.

Hopefully we will find some answers.
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Re: Oxalic Vapor

Unread post by cam bishop » November 21st, 2011, 6:32 am

Allen,

Do you think the chloroplast sheets with the hardware cloth over them are still ok to make drop boards. I note that you are not using them now. I searched the site and didn't see any links to how the ones you're using now are constructed.

On a side note, I'm seeing DWV on one hive that has been treated in August, September and November. This has been my best hive with the best production this year. I've always used Medhat's shaker and this hive tested below threshold in August but I treated anyway because it's so cheap and easy to do. I guess next year I'll monitor better and probably use the MAQS during spring and fall if drops indicate it's necessary. I'm also thinking of the MiteGone method, seems it's pretty safe for the bees and should be effective. Then if I use the OA vapor in the winter I should get better control.
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Re: Oxalic Vapor

Unread post by Allen Dick » November 21st, 2011, 7:35 am

Do you think the chloroplast sheets with the hardware cloth over them are still ok to make drop boards. I note that you are not using them now. I searched the site and didn't see any links to how the ones you're using now are constructed.
I think coroplast sheets are just fine. I just happen to have come by some screened floor hive bases that my friends were not using. The floors are made by TLS Sales in Saskatchewan and they are heavy-duty version of the Chapleau Apinovar screened floor with slide in and out drop board/solid bottom. That bottom is masonite and warps if not soaked with oil. I have smeared them with mineral oil and Vaseline. After the initial oiling, I now just use Vaseline. We'll see if that protects the boards from water. Vaseline sure does immobilize the mites.
On a side note, I'm seeing DWV on one hive that has been treated in August, September and November. This has been my best hive with the best production this year.
Was that with OA? Vapour or syrup?

That is often the way. Hives which raise a lot of brood are the best producers if the flowers are producing,and eat a lot if the flowers don't produce. The hives which raise the most brood also raise the most mites and that comes back to bite them at the end of the season when the brood rearing declines, the old bees die off, and the bee population declines to the off-season size. The mite population does not decline in the same way and maintains itself in any remaining brood and on the young bees. Since the mite population stays constant and the bee population declines and the 2/3 of the mites which were in the brood are now phoretic, then the number of mites that appear in a wash goes away up although the number of mites in the hive has not changed much.

Prolific and highly productive hives are more likely to have high varroa levels and can be difficult to sustain on soft treatments or no treatments compared to less productive and more conservative strains. This fact explains why many commercial beekeepers are not easily convinced to abandon Apistan, Apivar, Checkmite+ and/or the chemicals used in these strips.
I've always used Medhat's shaker and this hive tested below threshold in August
What count did you use for an August threshold?
but I treated anyway because it's so cheap and easy to do.
Exactly what did you do?
I guess next year I'll monitor better and probably use the MAQS during spring and fall if drops indicate it's necessary. I'm also thinking of the MiteGone method, seems it's pretty safe for the bees and should be effective.
I don't know the answer. I do know that when Apistan worked we never had problems. Strips, when they work, are easy. The other, so-called 'soft' methods are a lot more work.
Then if I use the OA vapor in the winter I should get better control.
I'm thinking that the trick to using OA is to make sure that the mites are knocked right down to near-zero levels before spring brood rearing gets going.

In areas where re-infestation from neighbours is likely, I don't know what the answer is except to keep watching and try to figure the best response when varroa are found.
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Re: Oxalic Vapor

Unread post by cam bishop » November 21st, 2011, 8:44 am

Was that with OA? Vapour or syrup?
Vapor
What count did you use for an August threshold?
I used 5 mites per 200 + bees. This hive had 3 mites.
Exactly what did you do?
I treated with OA vapor all three times. I should mention that several other hives in the same yard were over threshold, several with 8-9 mites/200+ bees. Since I had to treat some hives in the yard, I treated them all.

I'm thinking the MiteGone might be much cheaper in the long run for me... also that I can treat my nucs with them. The MAQS are expensive and can't be used on the nucs. I'm going to invest in a microscope and start testing for nosema and tracheal mites too. Sure different than when I was working with bees back in the '70's. Tough learning curve. You have been a very valuable resource. Thanks
Cam Bishop
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