As to whether it actually works or not I can't help thinking that if something as cheap as that was effective against a disease as unforgiving as blight everyone would be using it, legal or otherwise!
Not necessarily JG. They want to bamboozle you into submission
. Your logic might appear to be sound in a fair and above board world, but then many years ago most food products were happily dispensed in brown paper bags that were perfectly healthy. But that still didn't stop the oil/plastics industry barging in, sensing a multi billion dollar wheeze, citing untruthfully disease and pestilence, and taking over, creating a market for themselves where there was no need, and giving us the ludicrous result that some food products now cost more to package and deliver across the globe than the cost of the actual food content itself. Madness.
In healthcare, many perfectly serviceable safe and effective herbal treatments of hundreds of years were made illegal overnight, only for those very same herbs to be exclusively industrially grown and processed on a massive scale by those companies.
And if they can find a way of crowbarring in another lucrative farming market for some cheap mineral they mine or some monstrous chemical process they have exclusive rights on, they will, regardless of whether there is already a cheap, effective and natural solution being employed. I would go further in saying these companies have an interest in not solving issues like blight, but actually finding it preferable the disease remains everywhere.
Some old natural plant care remedies are not used, not because they are not effective, but purely because some big industrial Baron with a stick says it's illegal.
Let's be real here.