My friend has a hydro setup and he has 6 plants and on 2 of his plants a couple leaves have these yellow marks with some black in the middle it kind of looks like bird shit, does anybody know how this happened?

Thanks
sepehr Reviewed by sepehr on . Does Anybody Know What This Is? My friend has a hydro setup and he has 6 plants and on 2 of his plants a couple leaves have these yellow marks with some black in the middle it kind of looks like bird shit, does anybody know how this happened? Thanks Rating: 5