By Steragram
Pembrokeshire,
United Kingdom 
My poor tomatoes - now they have fungal leaf spot, quite suddenly all over both plants and few leaves unaffected. I didn't see any sign of it yesterday. Is there a fungicide I can safely use? Doesn't look as if there's much prospect of a harvest at this rate...
They are Oregon Spring, which are supposed to be pretty well seedless - important to me because of a gut problem and I was hoping to be able to have tomato again without deseeding them...
2 Aug, 2019
Answers
Yes, teaspoon of bicarb or baking soda in a litre of water with a small amount of vegetable oil & a couple of drips of washing up liquid. Shake well & spray. Might need repeated applications
2 Aug, 2019
Well there's some in the cupboard so nothing to lose. I have taken off all the infected leaves I could see and am off to put them on the bonfire pile. Spray bottle here I come.
Grandad G I looked up the link you gave and its for potassium bicarbonate rather than sodium - but maybe it doesn't matter. I have sodium b/c so will try that.
2 Aug, 2019
One thing I've been doing for years once my toms get to about 8 inches tall is spraying with aspirin. A quarter of a soluble aspirin per litre of water with a drip of washing up liquid. It creates a reaction in the plant as if it's being attacked by mould & boosts it's immune system.
Seems mad but has scientific backing & works for me in rainy Manchester
2 Aug, 2019
I've never tried this, but bicarb of soda supposedly.
I did hear some "scientific" explanation, all to do with PH values, bicarb being Alkaline
Or could be it would leave a residual barrier on the leaves
Whatever the reason, worth a try, and cheap
http://theveggielady.com/bicarb-soda-as-a-garden-fungicide/
2 Aug, 2019