Mould

[Nicky]

Yuck!

I dribbled oxalic acid on my bees today as it was a relatively warm day and found a build up of mould on the top of the crown board. I bought the the standard OSB Rose box, mesh floor and crown board from Thornes and started with my bees last August.
I did notice a small amount of black on the new box in about November .
Above the crown board which has glass covers on the holes is another OSB box and I had put a sack with some wood shavings in. I now have taken the sack away. The plywood side of that box was covered with black mould as well.

I know we are having a very wet year but the hive is in a sunny site with air access.

The bees are still alive.

Any comments about what I could/should do and why it happened and is it common?
Thank you
Nicky

[gavin]

Hi Nicky

Welcome to the forum!

As for the mould in your Rose hive, I don't have experience of these so I'm not sure. Generally stronger colonies have less trouble with mould than weaker ones. You need gentle ventilation which, in wooden Nationals, comes from leaving the crownboard holes open until the oxalic treatment when I usually put fondant on top, and the screened side vents in the roof carry the moisture away. Last winter at the association apiary I put a polystyrene roof on top of a wooden Smith with a plywood crown board and the black mould on that crownboard was the worst I've seen. The bees - a weak colony - survived and eventually built up.

One comment on the oxalic acid treatment. It may be far less effective now as many colonies will have restarted brood production and many of the Varroa will be safe in sealed brood. Much better to do the treatment in December when colonies are as near broodless as they'll ever be.

I wouldn't do anything. Swap it in spring for a new one, and sand it down to clean it a little - the bees will not mind the black mould.

Gavin

[Calum]

Hi
I take the outermost frame out on both sides, that seems to improve the ventilation greatly and stops mouldy frames.
Do you lay newspaper on top of the frames to prevent condensation dripping back down on the bees?
I replace that every few weeks and I have no problems.
BR
Calum

[Mellifera Crofter]

I've replaced all my wooden hives, except one, to polystyrene. What I found interesting when I looked in my only wooden hive a few days ago was how wonderfully dry it was compared to my experience of wooden hives in previous years. The only thing I did differently this year was to use wool above the crown board as insulation. (In fact - I put wool in all the hives.) Wool is the best material to absorb moisture without becoming soggy and therefore to remain warm. I bought off-cuts of wool insulation slabs. (If anybody considers doing that, make sure what it has been treated with even though the bees don't come into contact with the wool. Borax is ok.)

Rose hives have plywood sides - so not very warm. Could that have an effect on mould growth? (This question might link to Steve's question about Rose hives.)
Kitta

[Calum]

hi Kitta,
I suppose mould could feed of the glue in the plywood.
I'd slap on a coating of propalis on the insides that seems to prevent it, but I think everyone (and their bees) are doing this anyway.
BR Calum

[chris]

Nicky, where did the idea come from to put in a sack of wood shavings? Was it from the Warré quilt idea? I don't know the details of working a Rose hive, but just a sack of shavings,without other carefully thought out ventilation ideas, would probably just end with a soggy mess on top of the crown board.And mould. Even in the Warré hive where the idea of the bees adjusting the ventilation by propolising and depropolising as they need, the sawdust or other material in the *quilt* must be frequently changed.

Kitta, you say "Wool is the best material to absorb moisture without becoming soggy". Out of curiosity (and with another idea in mind) where does the absorbed moisture go?

[Mellifera Crofter]

... Kitta, you say "Wool is the best material to absorb moisture without becoming soggy". Out of curiosity (and with another idea in mind) where does the absorbed moisture go?

I'm not an expert, Chris, but I think this quote from Thermafleece's website will explain it:

Wool is a hygroscopic fibre and is capable of absorbing more moisture than any other natural fibre due its high fibre saturation point. This means that wool can absorb nearly 40% of its own weight in moisture and still feel dry to the touch. Because wool binds moisture rather than just absorbing it, the performance of our insulation does not vary significantly as humidity levels in the building change. This can help contribute towards a more comfortable and healthy indoor environment.

I have changed a couple of wool slabs over for fresh ones in two polystyrene hives but I don't think it was really necessary. Only the outside edges of the slabs where it touched the walls were slightly wet.

Kitta

[chris]

Ok, I understand now.I thought you meant just a fleece. I've been using wool insulation above the crown boards and in the partitioned off parts of my wooden hives for a while now Non treated; from our sheep. At first, it became damp, and also encouraged mice and entrapped stray bees. So I now put it in a plastic rubbish bag and then fit that into the available space. Works fine for me too.

[Easy beesy]

hi Kitta,
I suppose mould could feed of the glue in the plywood.
I'd slap on a coating of propalis on the insides that seems to prevent it, but I think everyone (and their bees) are doing this anyway.
BR Calum

Hi Calum

Where does one get enough propolis to 'slap on a coat' please?

[Mellifera Crofter]

... Non treated; from our sheep. At first, it became damp, and also encouraged mice and entrapped stray bees. So I now put it in a plastic rubbish bag and then fit that into the available space. Works fine for me too.

I've torn up an old sheet that I put above the crown board, and then the wool. The bees can't get there and definitely no mice. I can't understand why your wool became damp. Did you wash it first to get rid of most of the lanolin? My feeling is that oily wool would be less absorbent than washed wool.
Kitta