Rust, rust and yet more rust

Being Italian I have long grown garlic in my garden.
Twenty years of mucking, sanding, and seaweeding (??) has not endeavoured to make the blue clay any more tractable so that my cloves have never reached any significant size. still, I was able to have fresh garlic and was content.
Last year I was lucky to become an allotteer at a site with a subsoil of yellow clay and the loam is much looser. Anticipating a bumper crop I planted masses of garlic.
The result was even less satisfactory than at home for the whole lot got so affected by rust that the stuff even tinged the soil red. The plants wilted and the cloves were only good for flavouring my olive oil for so small they were I was able to insert them through the plastic pourer.
Never having come across the stuff and trying to be organic, I did not act sufficiently early nor would I've known in what manner to act.
Any suggestions for next season?