Ok, I see your point. Still, I am pretty surprised it could all go from a good green lawn to this in just 3 weeks due to fungus alone. I think gray leaf spot can do that, but not brown patch, which takes longer to spread this much. So I wonder what the fungus is. First, he needs to look at the leaves to see whether there are the usual fungus signs, ie brown spots, slimy grass, etc. If so, he can take some clippings and put them in a bag overnight. Gray leaf spot will show up as a gray mold instead of the cottony stuff you get with brown patch, dollar spot etc. Could be grubs, but there would have to be a heck of a lot to do this.