Is this mildew on my peas?

Looks like mildew. You need a fungicide, but be careful, this is a food plant, check the labels on the bottles to see if its okay for them.

Looks like mildew to me, if it is if you can spray heaverly twice a week with a mixture of 1 part cows milk to 9 parts water, which I learned from another gardener this way there are no harmfull sprays If you go to my blog 2 intergrated growing you will see

Next year, give your plants more space to improve the airflow around them - which helped cause the problem in the first place.

Thanks MW, I always try to pack as much in as possible as I only have a small garden. Although I do know what you mean, it happened last year as well.