cladosporium leaf spot of spinach
Cladosporium leaf spot-lesions are often round. Sporulation may be observed with a 10X hand lens. The outbreak in these photos was in a high tunnel.
Figure 1. Cladosporium leaf spot of spinach. 
Figure 2. Cladosporium leaf spot of spinach. 
Figure 3. Cladosporium leaf spot of spinach.