Leek rust and other diseases

Since the weekend leek rust seems to have spread throughout our crop of leeks. These are orange (rust-like) spots and can infect any member of the onion family:

According to the RHS there are no approved chemicals to control it. I just removed the worst affected leaves and hope that it won't do too much damage to the crop. It probably does'nt help that we planted the leeks quite close together.

Powdery mildew is also evident on the plot. Some of the pea plants are affected:

The courgettes (which have nearly finished now) are also affected.

Finally, our lobjoits cos (left of below pic) have yellowing outer leaves:

I have no idea whether this is a disease or not? The lettuce on the right have grown a little bit but it is not likely that they will make it to adulthood with the cooler weather.