Weird Landscape blur Spots, don't know how to fix them

Hey,

I created my landscape in Gaea and I am getting this really strange spots on my landscape.

they were not there when Imported and added the Landscape Material, but when I hit play button, they suddenly appeared and now they won’t go away. I have done a build level to see if this would fix it but it did not work. Does anyone know why i am getting this problem?

Thanks