Any thoughts on what could be causing this? Fungus? Chinch bugs?
Look like lack of water to me, do a screw driver test on those spots and see if is dry.
Either lack of water or disease. Whatever you do, it will not respond this season. And whatever you do, it will look great in April. That's how zoysia works.
I did the screwdriver test and those areas were very dry. Watering more and it is already greening up!
Thank you both for your responses!