Sweet pea seedling problems - something eating them!

Hi,

I have some sweet peas that have self sown from last year and some that I've grown from seed and have just put outside yesterday.

Some of those I planted out a few days ago are now showing the same damage as the ones that self sowed.

Please advise! I dont know whats doing this and how to sort it.

Ive been trying to add pictures but this doesn't seem to be working : (

Ok its like a hole in the leaf with brown/ decay see through patches around the holes... I can email pics if anyone wants...

Also I've grown them for 2 years now and they are lovely. They don't usually last all summer though as they get powdery mildew (I think) and the plant dies off although it does flower for a little while after that starts.

Does anyone know how to stop this?

Thanks so much!

Eve