Posted: 14/07/2016 at 21:55
They don't normally do too much damage - I remove any really dodgy leaves, but you do seem to have a lot.
Are your plants a bit crowded? Good air flow helps to keep plants strong and healthy. Pests and diseases often happen more on weaker plants, so the sturdier they are when planted, the better.
Sweet peas like a good rich soil so it's important to give them enough food when they're in pots, once they start flowering.
Hope that's a little help. We have a dedicated sweet peas thread here. David will be able to give you more advice there. It's called Sweet Peas Know How