your reply does not address the question about whether humble baking powder prevents or cures blight,
Now, now JG. As we all know, nothing
cures blight.... certainly none of the legal products. And let's not get into the old 'conspiracy' routine please... it goes nowhere and halts reasoned talk in it's tracks.
On the subject, it is quite apparent from the methodology of the present blight priests that most of the treatment is all about surfectants, and trying to keep the spores off the plants... I think we can all agree on that.
I'm no chemical expert thankfully, but many of us will understand the properties needed, and I would imagine baking powder would work, as might some sort of chalk possibly, and of course most growers know that milk has been used as a barrier aid over the centuries with many plants. There are many substances that could play a role. That's no conspiracy, that's a fact.
Let's hope the EU/Westminster bunch have a replacement in mind.
In the end, it doesn't concern my growing of potatoes, as I have never sprayed them with anything.