[Caltonbanks]

Hi All

Before I start I should mention that I am not a scientist or a mathematician so it would be greatly appreciated if any answers are kept in laymans terms.

I have orchids in my garden and they are suffering from a downy mildew problem. I also have lots of moss and algea (and possibly many other garden nasties) in the garden.

As any gardener will tell you, downy mildew is really hard to shift 

Having done some research I found what is supposed to be a brilliant product for treating many fungal problems, Physan 20 (see link: http://www.physan.com/Resources/Physan%2020-DRUM-EPA-2010-2cl.pdf ). But, this product is not available in the UK and it would take weeks for me to have it shipped from the US. By this time all my plants could be dead.

Anyway, I was told on another forum that this (BAC 50 see link: http://mistralni.co.uk/products/c10-c16-alkyl-dimethyl-benzyl-ammonium-chloride-ba ) is the active ingredient in physan 20 and it will do the same job.

However, I now face another problem, which brings me to my question. How do I dilute BAC 50 down to the same strenght as Physan 20?

P.S. I know this is a science forum not a gardening/chemistry forum, but I dont really feel safe asking a gardener how to dilute chemical concentrates. 

[Arkcon]

Well, I'm glad you thought of us for all your home formulation needs.   Using your references, it appears you can buy a 50% solution of this particular detergent, but you need a 20 % solution, to kill fungus without harming the plant. (Although your reference doesn't really support this -- 20% solution is just for non-porous sterilization) So that you'll be able to handle the next dilution problem you come up with on your own, can you work out what you need to do?  Consider:  if you had pure BAC, and you mixed it half and half with water, what concentration would you have?

[Caltonbanks]

Hi Arkcon

Thanks for the reply

Once I have the 20% solution (physan 20) I know how to mix it for various uses as this information is available from Physan 20.

And to be honest I think I know how to dilute the BAC 50 down to the same strenght as the Physan 20. But I would rather be safe than sorry. Thats why I asked here.

So if I give you my working out, would you be able to tell me if it is correct?

------------------my working out-----------------

BAC 50 is 50% water and 50% BAC

Physan 20 is 80% inert igredients and 20% BAC

So if I was to take 4ml of BAC 50 then add 6ml of water this would give me 10ml of Physan 20 (equivalent)

(4ml BAC 50 + 6ml water = 10ml Physan 20 equivalent)

Then if my thoughts are correct, I should be able to use the homemade mixture in the same way as directed for physan 20.

--------------------------------------------------

So is the above information correct?

Thanks again