Probably the best I can do with my iPhone camera
Green/dead looking:
Green:
From a quick search, it looks a lot like ascochyta leaf blight, but I could be wrong
Absolutely a fungus, you need to treat for that. I’ll try to dig around tonight.
Here is the important thing, whatever fungicide you use, follow up with a second application or else you can end up with a resistant form of the fungus
And you need to sharpen you mower blade(s). 
It’s a brand new blade 
I’ll try swapping to the one I had sharpened though
I wouldn’t worry about the blade…I see fungal damage not torn blades