anthracnose of pumpkin
Anthracnose of pumpkin and squash-The lesions on fruit can cause the fruit to be unmarketable. However, the disease is not common. I have never observed lesions on leaves.
Figure 1. Lesions of anthracnose on pumpkin fruit often consist of round, dark rings on the fruit surface. 
Figure 2. Anthracnose lesion on pumpkin in comparison to a quarter. 
Figure 3. Anthracnose lesions of differing ages on pumpkin.