My Empire Zoysia grass/lawn has grubs or fungus. There are brown spots (grass looks dead) on my lawn. These areas can be very easily pulled up like a carpet.
Empire Zoysia Grass Has Grubs or Fungus
Certified GKH Gardening Expert
I would recommend digging up a small section of your lawn and confirming the presence of grubs. More information on how to do this and information on grub control can be found here:
If it's not grubs, it could be a zoysia disease such as brown patch, leaf spot or rust, all of which are explained in the following article: