black patches on sun flower leafs

[Philbasford]

I went up to the allotment this morning and noticed that a group opf sunflowers ive got in a group seem to have small black patches on thier leafs, i thought it might be aphids but looked closely and wasnt, the plants are otherwise in very good health, does anyone have any idea what this might be?

Thanks

Phil

[Philbasford]

[saddad]

If they are so small could they not be bristles? like Aubergines have spines, to discourage things from eating them?
???