hello, i have no idea but these are just some of my thoughts:
when you say grey mould, is this an actual disease or do you just mean they went mouldy and it was grey?
If its a real disease is it specific to tomatoes? (as you said the other plants are so far unaffected?
If it's just mould, could it be due to a lack of ventilation and the tomatoes happened to be in the least ventilated part of the tunnel?
mould = spores
what about spraying the inside of the tunnel fabric with a mould killer like you would use in a shower to kill off any spores?
be careful about transferring spores to other plants via your hands
all this is probably no help, but i'm interested in what others may think!
ceri
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