Any Landscape Guru's in here?

I lost about 14 Leeland Cyprus Pine trees this winter due to ice, and Im in the process of re-seeding the area that they were in for almost 17 years. Ive gotten grass to grow (Vigoro Contractors Fescue Mix) everywhere except for where the tree stumps themselves were. So I have about 14 dirt patches that are about 2 feet in diameter, with grass growing just fine in between them. What would cause this? The stumps were all ground down and we picked and dug out as many roots as possible before seeding and putting straw down.
I realize that most anything that grows will be barbequed by the summer sun, but Im just going for erosion control until I can overseed again this fall.

 

Might need to lime that area due to the acidity left by the trees. Best thing to do is purchase a soil test kit off Amazon and see exactly what the soils lacks. Fix and it will grow.

 

As above.
I have several cedars on the left side of my property. Grass never grows there and I've been told lime as well. Just havnt gotten around to it.