Doesn't necessarily follow. In fact the growing conditions here are just about optimum, without major fungal disease problems, for a very wide range of vegetables and soft fruit, including all brassicas, nearly all leaf crops and roots (potatoes excepted), most legumes except the subtropical beans, and some grains (barley). Among the widely-grown crops the main exceptions I can think of are potatoes (blight), curcubits and the 'fruiting' vegetables (tomatoes, peppers, aubergines etc - but here these are mostly grown under glass anyway), some soft fruit (particularly strawberries) and wheat, which really prefers lower humidity.
I grow all my own vegetables and fruit, and I find I grow more or less organically not out of conviction or because the results taste better (which, for the most part, they do!): but simply because that with my local soil and climate chemical inputs are rarely necessary.
Of course, I wouldn't extrapolate my own conditions as a small grower to the very different requirements of large-scale commercial production: but even there, I think that you'll find that in the widely-grown crops, with the exceptions I've mentioned, the chemical inputs are predominantly for yield and pest control rather than fungal disease control related to damp.
Your Prince is German, pass it on.