re: Grass Help needed - What is wrong with this section of grass in my back yard?

Just a thought... my neighbor had this issue, recurring, and it turned out they were mini-sink holes from where builders had buried construction debris 20 years ago, and the slight divet is where water would pool, thus fungus, regardless of what fungus treatments were used. You couldn't really tell they were sink holes just by looking, they were very slight. Once he figured it out though, it was obvious. He leveled them all out with sand and the bermuda took over quickly.