Can you take a close-up pic of some grass blades growing at the edge of the damaged areas?

Here are a couple closeups at the edge of the diseased areas. Hope these are useful. Thanks for the help.

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Any ideas?

Based on the pictures you sent, I would say that it is Pythium Blight and is easily treated by applying additional nitrogen to those areas that are most affected. This is a very common problem during periods of heat and high humidity

Also, make sure your mower blade is sharp as a dull blade will aid in the spread of disease.

Lastly, continue to only water early in the day so that your lawn has a chance to dry out before nightfall.

Best Regards,
Byron

Thanks Byron. I appreciate your help. I will try everything you mentioned. After reading many posts here, I just changed my watering schedule from 15 minutes per zone every day to an hour per zone 2 days per week. Hopefully this all helps. Thanks again.

>"I just changed my watering schedule from 15 minutes per zone every day to an hour per zone 2 days per week. Hopefully this all helps."

No, that won't help and is the reason you have disease problems.

>" After reading many posts here"

No, no you didn't. If you did you would have read "deep and infrequent irrigation" not shallow and often.

Always deep, infrequent watering. Your lawn needs one inch of water per week including rainfall. Using tuna cans placed in various places, run the sprinkler to obtain one inch of water in the tuna cans and time it. Run the sprinklers each week for that amount of time in every section to achieve one inch of irrigation all over. One inch will moisten the soil to a depth of 6-8 inches. This encourages the roots grow deeply. The soil will pull the water downward. The roots will grow down looking for water and nutrients. Watering once a week allows the grass blades to dry, avoiding fungal issues. Constantly damp grass promotes pathogens for fungus and disease.

Each week, be sure to take rainfall into consideration.

gary .....would this disease preceed itself by mushrooms growing? I had this problem last year when a new lawn was laid, and told to water AM and PM after two weeks grass showed signs of turning black and dying. A lot of rain last year plus my watering produced mushrooms. Tried laying new pieces of grass this year and find that it too has died out.....but preceeded by mushrooms. I do tend to water after work. I see now the error of my ways. Do I need to dig this all up and begin again or if I put down nitrogen and water in the AM will this in time cure itself?

Don't worry about the mushrooms. It only means there is moisture and decaying wood product in the soil. Have fun with a 9 iron or just grind them up when you mow.

re: nitrogen. Never apply nitrogen to sick grass. Black and dying is sick grass, period.

First thing you need to do is let that grass dry out and then start watering properly.

*Too little water - not a good thing.

*Too much water - that's worse! ... and keep in mind you have mother nature throwing you curve balls with her rain storms!

As I stated previously, "As a general rule of thumb" - "Turf grass requires 1" of water per week" and that is your baseline, you adapt to your property from there.

Over and over you hear, 'deep and infrequent, deep and infrequent' and this is what that means. Give your lawn the general guide line of 1" of water, all at once ... before you move the hose to the next section. How long before you move the hose differs from house to house so you must first do a simple test. Take empty tuna fish cans, cat food cans, heck even a few old-fashion rock glasses from the bar will do, anything similar and place a few around the yard where the sprinkler will touch. Note the time and turn the water on. After 1/2 hour, shut the water off and look at the cans - you might be surprised at what you see. Newer homes with clean pipes might fill that can up in 30 minutes, it depends on your water pressure and hose. Most homeowner with clogged arteries, I mean pipes narrowed because of sediment and deposits, will see that after 30 minutes there's barely a couple ounces in the cans. Turn the water back on check another hour later then. When you find your cans are filled, be it 2 hours and 15 minutes or other, this is the amount of time required to apply 1 inch of water to EVERY section of the lawn that your sprinkler can cover. And even this can vary because if everyone on your block is taking a shower and washing clothes when you water your lawn the pressure will be different than when you did your test.

Applying 1" of water all at once provides the deep irrigation just like a good rain storm. It allows the water to soak down to about a 6 inch depth where the roots reside. We irrigate the roots, not the blades of the grass for a healthy and thriving lawn.

Infrequent means like mother nature. It doesn't rain 1/2" every week consistently anywhere, nor does it rain only on Thursdays. So this means do not water every Sunday morning because you wake up and head out to get the Sunday newspaper and stop at the local bakery. You adapt. You water your lawn the next time when the grass tells you to do so! During the cooler spring time, 2 weeks might pass before the grass tells you it needs to be watered. During a summer heat wave, that might only be 4 days between watering. You adapt. Adapt to the weather conditions. High direct sun, high winds will dry the lawn faster. Cloudy days, high humidity will dry the lawn slower. You adapt. Adapt to your soil conditions too. Sandy soils will drain faster which causes the need to water more often per season. Clay soils retain water, which cause the lawn to be watered less frequently overall throughout the season. The grass will tell you when to water it. Water infrequently not on a schedule. Your lawn knows no calendar,

Drought stress is a condition when the grass tries to protect itself ... it is when the grass tells you it needs water. When the grass needs water the grass blades will fold in to hide from the suns rays, the grass turns a blueish gray color. When you walk across the lawn, your footprints will remain and show up even after a couple hours have passed. Even when you walk on the turf, it seems extra dry and almost stiff and it cracks and crunches under your foot. This is drought stress, this is the grass telling you it needs water.

You come home from work early in the evening and notice the lawn. Near the garage, where there is some shade late in the afternoon, the grass looks great. But in the middle of the yard, where the sun hits it all daylong, you see it is a different color ... it's a little darker ... looking at an angle this way, it look gray. Also, this is where the kids run around and you can tell they were running around today because you see their footprints - the grass looks all trampled, it looks beat up. Yes, it's time to water - the grass is telling you so.

So the grass is telling you it needs water, but don't panic. The timing of WHEN you water is very critical in my experience. It's 6:30 when you notice this drought stress - it's dark at 8:30. If you water now, by nightfall your grass will be damp and stay damp the entire night. This dampness is what causes Disease and fungus. Relax, do not panic. The nightfall brings cooler temperatures, might even bring a dew the next early morning. The turf grass will not suffer any further drought stress if you wait - it actually will improve, it will be fine. The timing of irrigation is so important in my opinion. Not watering that evening when you notice the drought stress is the smartest / best thing you can do it.

OK, so I convinced you to wait and hold off on the watering that evening and later you watch the evening news. The weather man predicts the next day to be a high of 82 degrees, sunny and a nice breeze at 10 to 15 MPH. Beautiful - that's PERFECT! Have an in ground irrigation system? Set the system to start at 4 AM and be finished by mid morning. Have two areas to water like I do? Use two hoses and two sprinklers with a timer set to start at 4 AM. No irrigation system, no timers? Either you buy the extra hose and timer or you set your alarm clock for 3:50 AM. because you have to move the hose later and then shut things off before you leave for work. Maybe you start early? Set the alarm for 2:50 AM then!

Watering early in the AM is the best you can do. This allows the water to penetrate into the soil when it's cooler and not evaporate rapidly because the soil is hot from the sun, and the early AM watering, most importantly, allows plenty of time for the lawn and its actual grass blades to dry out from the warmth, sun light and wind. Dry grass blades are number one to disease and fungus prevention. Dry leafs are foremost and paramount in your turf grass's overall health.

When you have humid nights, damp grass blades that can not dry out, you're asking for trouble. Factor in tall grass that should have been cut a while ago, grass that is growing above the breeders recommended height along with damp, wet grass and you have a recipe for disaster.

See? You adapt. It is a living thing that we take care of like a parent. You adapt your mornings when you have to drive your child to his/her early morning engagements, you adapt you normal morning schedule for your lawn too. But you can fine tune your early morning according to the weather. If it is going to be the perfect day of sunny and breezy, you could water a little later in the morning like 6 AM instead of 4 AM because the sun and air movement will dry the turf quickly. However, if it is going to be a cloudy, muggy and humid, still day, you need all the time you can get to allow that grass to dry out after watering. You do need to start very early in the AM ... you adapt if you must drag a hose in the morning. With an in-ground irrigation system it doesn't matter because you just hit the button the evening before.

Speaking of the in-ground systems and their timers, remember your lawn knows no calendar or schedule. Do not have the system water every Friday come hell or high water. Do like the above, let the turf tell when and then press the button that evening.

Will do as you suggested, in fact started an hour ago, perhaps a bit late, but it is a start. No irrigation system, but no problems with up early. A lot of patches out there, but for now will water as you say.

Thank you so much for your detailed evaluation. I am not new to this yard, 40 years , and always had perfect grass. About five years ago began this experience, perhaps I am not following a good fertilizing program, suggestion? Have a great day! Jacque