Leek Rust

This fungal infection is more prevalent when the autumn and winter are unusually mild. Leeks growing in soil which is rich in nitrogen but lacks potassium are particularly vulnerable.  The symptoms of leek rust are orange, powdery spots on older leaves, which later turn yellow. Although they are disfigured with mild rust infections can still be eaten.  Badly infected plants should be dug up and destroyed.  To control the spread of the disease, spray the remainder of the leaks with a fungicide.