Kitchen Garden Forum

I know its early in the year to be asking thjs question but does anyone know the formula for blight spray which incorporated blue stone and washing soda?Does anyone still use it? Are there any pros or cons in using it instead of modern sprays?

I think you are referring to 'Bordeaux Mixture'. This used to be widely available in garden centres but I don't know if its still available. It is simply a 1:1 mixture of hydrated copper sulphate (blue stone) and calcium hydroxide (hydrated lime).
For the small quantities that a back yard gardener needs I don't suppose making your own mixture a practical proposition.

John

I think you are referring to 'Bordeaux Mixture'. This used to be widely available in garden centres but I don't know if its still available. It is simply a 1:1 mixture of hydrated copper sulphate (blue stone) and calcium hydroxide (hydrated lime). Another version of this, called 'Burgundy Mixture', is a 1:1.25 mixture of hydrated copper sulphate and sodium carbonate (as washing soda).
Copper sulphate is available from places like Chemdirect and washing soda from your local supermarket. For hydrated lime I suppose you'd have to try your builders yard.

For the small quantities that a back-yard gardener needs I don't suppose making your own mixture is a practical proposition.

John

It is still available.

Thanks John and Peter for your replies. Its my first time to use a medium such as this and I am delighted to get a reply so quickly. :

Hi - I've just joined the gang of bloggers on this site and noticed your note about Bordeaux mixture. The reason it's not widely used, is that it's actually poisonous and very unpleasant to use. If you're mixing it yourself with hydrated lime, you need to be aware that this will burn skin especially if there's any sweat. The dust of the lime will mix and start burning. If you are intending to use chemicals you're better off buying a proper blight spray that is non-toxic. Dithane has been around for years and is completely harmless (but not organic).It's a protectant so it's a prevention rather than a cure.

If you ever notice that when the farmers spray anything, it come out in a very, very fine mist,under pressure, using extenended booms, to reach all the plants.

In this way the tops of every leaf gets completly covered by the spray, giving total protection. When you or I spray there is little pressure and all of the plants do not necessary get covered.

I am not against you spraying, but you will have great difficulty finding a spray nozzle big enough to spray a lime mixture through!
I have used various sprays against blight over the years, and as far as I am concerned they were useless, a waste of time.

Cheers

Hi Pollie Tunnel and Lurganspade,
Bordeaux Mixture certainly is very slightly poisonous but you should be made aware that it is the only treatment against Blight in Potatoes that the Soil Association will allow under their accreditation scheme much to their discredit.
If, when you are spraying, you do not use the recommended protective attire then you may get an unpleasant reaction and certain components of Bordeaux Mixture may cause burning. You are looking at the chemicals dry and how thew will react but when in liquid form and sprayed if you are using the protective attire you will come to no harm.
Bordeaux Mixture is very easily sprayed with a Knapsack Spray Unit and also easily sprayed with the normal Hozelock Spray Unit. In this area Bordeaux Mixture is very easily obtainable.
I only grow Early Potatoes on my vegetable area so avoid the blight but I do have a commercial interest in main crop Potatoes.
JB.

I used this last year and it seemed to work OK - have only just used up the last of our 2007 spuds. But does the spray on the foliage get down to the tubers, or does the "poisonous" aspect just refer to danger to the sprayer?
John N