Q. See if you can figure out what’s happening to our lawn. It is dying. I’m very bad with technology so I’ll have to send each picture in separate emails. A. First of all, you did a very good job with the pictures. They all came through just fine. Dying lawn from unidentified causes. It is very difficult to determine a problem with the lawn from pictures. Lawn problems basically boil down to three types; disease, irrigation or insect problems. Sometimes it can be a combination of these.             The pictures make me lean towards a disease problem. The first picture you sent had a combination of two grasses in it; tall fescue and there was a patch of what I think was ryegrass in the center of the picture. In that picture, the problem only affected the tall fescue and not the ryegrass. The lawn has a color difference that you can see which is actually due to a difference in “texture” more than color. Different grasses have different “textures” due to the reflection of light on the leaf surface. This textural difference is a good indicator that more than one type of grass is present in “patches” and not mixed together.             Lawns dying because of irrigation usually die in a specific pattern related to the irrigation sprinkler heads. Sometimes this pattern can be in between irrigation sprinkler heads and sometimes the pattern can be close to irrigation sprinkler heads. It depends on a number of factors including the nozzles that are used, operating pressure of the system and the design of the system.             Homeowners that design their own irrigation system usually tell me it’s not due to design because they “did it themselves”. Good irrigation design is not something that most people can do. It is much more complicated than people realize. Not the lawn in question. Grass suffering from drought will grass near the damaged area with a darker appearance than the rest of the lawn. This is because blades of grass either “roll” or “fold” in response to a lack of water and cause this darker appearance during times of drought.             There are many landscape contractors who are skilled at irrigation design or they purchase the materials they need from companies that provide for them a professional irrigation design. Fly-by-nighters will not be skilled in this area.             Poor irrigation coverage or management will contribute to disease problems and lawns. It is imperative that a good looking lawn has an irrigation system that is designed and installed by professionals.             Poor irrigation management will contribute to disease problems. Never irrigate a lawn if there is more than three hours of darkness after the irrigation has been completed. A wet lawn sitting in darkness for more than four or five hours when temperatures are above 80° F has a very high probability of becoming diseased. In other words, “Never put a lawn to bed wet.”             I was not in town in September and I understand there was a long period of wet weather and warm temperatures. When I heard this, I was thinking this was an ideal condition for disease development in lawns.             Disease problems may develop in a pattern or they may not. It really depends on the disease and to a lesser degree the management decisions applied to the lawn. Judging from the pictures you sent and what I have seen historically here I lean more towards a disease problem. Diseases in lawns frequently develop some type of “pattern”. Not always but it can be a good indicator that a disease is at work.             What to do? Diseases will run their course until there is a change in the weather or management practices. If this disease problem began during September rains then the lowering of temperatures and low humidity stopped the disease from spreading further. It will probably do little good to apply any kind of fungicide now.             We are getting to the tail end of the lawn planting season. I would make a decision to either replant the lawn from seed or sod but you should get it done by the middle of November at the latest.             If you decide to re-plant from seed then mow the areas that are dead as short as possible and rake or power rake these areas until you see bare soil. Seed these areas with a good quality lawn grass. If your lawn is predominantly tall fescue, then select a good tall fescue blend and don’t use a cheap one. If you are going to lay sod in these dead areas, rent a sod cutter and lay some new sod in these spots.