If you still have a lawn in the Las Vegas valley, I feel your pain. Lawns seem like they are a dying breed in our valley. But rest assured, they have their place even if you feel a bit slighted. This is a disease problem. You can tell because it is scattered through the lawn and the pattern cannot be tied to the irrigation system directly. It is also possible it could be an insect problem but not likely if it is tall fescue.             Lawns provide a great deal of comfort in a desert landscape. It is the only plant surface that is durable to foot traffic and stays a cool 95F even if temperatures soar to 115F or more. Since our body temperature is normally around 99F, a lawn remains cool to your touch. Asphalt, cement and synthetic grass will hit 160 – 170F in full sunlight on a balmy 105F day. I know. I measured it.             Lawns have their problems particularly this time of year. If you miss an irrigation, have a plugged or broken irrigation head, or a poorly designed or installed irrigation system you will see the results now as brown spots popping up which may die. A lawn in this inhospitable climate without a really good irrigation system is disaster. See how the spots are distributed through the lawn? Disease or insects because it is a random pattern. See how the grass looks healthy around the spots? The disease timing for treatment with a fungicide has passed. Fungicides are preventive, not curative. You have to catch it earlier to use a fungicide.             Then there are diseases and insect problems as well. Those with a tall fescue lawn will see fewer insect problems but there are a couple of serious disease problems that popup this time of year. They usually start appearing in late July or in August, oftentimes when the “summer monsoons” enter the valley from the south.             The biggest culprit for fescue lawns is humidity coupled with high temperatures. The humidity at the lawn level is entirely different from the humidity you feel. As I used to hear Linn Mills say, “Never put your lawn to bed wet.” How true. Never, never irrigate your lawn in the summer with only a few hours to dry out before it gets dark. Irrigate any time after 2 am but before the sun comes up. This is drought. If you look at the centers of the dark green spots you will see sprinkler heads. The sprinkler heads were spaced too far apart or there was inadequate water pressure to give head to head coverage.             Other things that reduce the humidity at the lawn level and reduce disease problems are to avoid thick, dense lawns during the summer months; if you fertilize in the summer use very light applications during the hot months; dethatch your lawn (it thins the lawn and lets humidity escape) in September or October when fewer weeds will try to invade; mow a bit shorter during the heat to let moisture escape.             I will post some pictures of common lawn problems on my blog. Come take a look.