Definitely looks like a disease. I would suggest corn meal @ 20-30lbs per 1000sqft every 3 weeks until conditions improve.

Water when grass shows signs of wilting and ONLY in the early morning.

The distinct lines suggest excessive spring fertilizer applications rather than a disease. Here's a link to a picture of a lawn that had excessive spring fertilizer applications.

Excess fertilizer picture

-Deerslayer

Your absolutely right deerslayer. I've never seen anything like that before.

Shows how much this Florida Cracker knows about cool season grasses.

I have a couple questions. Which Lesco fertilizer did you apply? Did you apply it with a drop spreader?

-Deerslayer

Thanks for weighing in guys.

The pre-em was Dimension .10% w fertilizer, 19-0-6

http://www.lesco.com/?PageID=27&ItemNumber=080381

I did the application of this in a split ap, half in in late March, the other half 6 weeks later. It was done with a broadcast spreader, rate cut in half and done in two passes @ 90° angles.

Water has been held back until lawn shows signs of needing water, darkening color, slowed growth, 'crunchy' when walked on.

I wish I had taken pictures when it was the stripes only. There were 3-4 long stripes that coincided with where my lawn mower wheels would have been on that certain mowing pattern. At that time, I really considered it an isolated problem that would clear itself up. Now it is really spreading.

No synthetic fertilizer since that pre-em app

Rob

Now I'm puzzled. Usually, a broadcast spreader will not leave well defined, thin stripes.

Is there a possibility that your lawn mower wheels picked up some nonselective herbicide? This can happen by rolling your mower through an area that was recently treated with Roundup or something similar.

Several years ago, my wife treated some garlic mustard that was in the woods with Roundup then walked across the lawn. Here footsteps browned the lawn for about 50'. Each footstep was clearly visible. Needless to say, I wasn't a happy camper!

-Deerslayer

No Roundup in use in over a year. I'd be curious about picking something up from the neighbors but as you can see I'm on a corner lot and the nearest neighbor is 2 lanes of concrete away. The portions of my lawn that are near a neighbor do not exhibit the issue.

Does anything about the switch to organic bring anything to mind?

Is it possible that grass would just up and die/go dormant due to thatch? As you can see from the rest of the yard, it isn't a global water/fertilizer issue. I can only figure that the reason the stripes showed up was due to the mower wheels finally trampling the grass so much it couldn't cope. Additional watering hasn't kicked it out of dormancy so I'm guessing it's dead. Now the spreading has me worried.

I'll try to cut up a section showing the amount of thatch in those areas compared to nearby normal looking turf.

Thanks again....

Rob

Does your mower have a minor fuel leak?

Not that I know....that's a thought. I wouldn't think that would be the case with the non-linear growth of ailment but I suppose anything is possible.

Some new photos just taken after mowing the yard. I picked an area where the sharp transition between good and bad is to show how quickly the lawn goes from gorgeous to dead.

Showing the thatch layer....this looks pretty thick to me. That said, the good portion has the same thick layer. Not sure what would have tipped the dead part 'over the edge'.

And here's another shot better showing the stripes heading toward the back yard.

How compacted is the soil? Could the lines be your tractor paths? I noticed that the soil looks clumpy and the roots don't go deep. Does it smell anerobic (bad) or earthy. Could the patchlayer be the original sod? I always use seed and can't comment on sod issues, but after 3 years I suspect it would be as established as it will get.

I don't know if this could cause or contribute to the browning of the grass, but how short do you mow the grass? That looks awfully short for KBG.

I can't tell if there's a disease, but I suspect there is. Some of that's cultural practices, and better ones will control it. Or help to control it. The initial marks could have been fertilizer burn, except you're organic and it's less likely. Maybe they were ruts from the mower cutting the grass way too short?

One, raise the mower blade! Go to 3" or more--whatever the top deck on your mower is. That will encourage deeper roots.

Two, dethatch, but it has to wait until fall (call it Labor Day or thereafter, but no later than four weeks before your first hard frost). You'll probably have to do it twice, once in each direction. That is one heck of a thatch layer you have going there, and it's encouraging disease.

Three, water only once a week (well, twice if the weather is really brutal) and before 10 AM.

Four, you may have to reseed after dethatching. It depends on the damage...

Thanks guys.

Compaction - the house was built 3 years ago on clay. It's in need of aeration and compost for sure. That's in the plans for this fall. No tractor ever on the lawn, just a push.

The mower is a Honda HRX set at the second highest setting. Been there since spring. I usually leave it on the second highest because otherwise the grass mats something fierce! I've resorted to bagging it every 3rd time just because the grass starts laying over and it needs a non-mulch pass to suck it upright.

I suspect the spongy soft thatch layer is hurting my effective mowing height. The wheels sink in the soft stuff and the grass plant (which almost looks like it's rooted in the thatch layer) is cut shorter as a result.

Great Pics! You defiantly have a serious thatch problem. Which I'm sure is the root of your problem. (sorry, no pun intended)

Is it possible that grass would just up and die/go dormant due to thatch?
Yes, Thatch restricts water penetration into the root zone, nutrient uptake and air circulation to the growing roots.

I can only figure that the reason the stripes showed up was due to the mower wheels finally trampling the grass so much it couldn't cope.
This is possible, but I doubt it. It doesn't explain why these areas are spreading. I see a lot of irregular shape spots throughout.

Does anything about the switch to organic bring anything to mind?
It could be that with the synthetics, you were applying just enough to keep the grass alive/force feeding it. All the nutrients were staying in and contributing to the thatch layer. With organics, the soil microbes have to digest the food before it becomes available to the plant. The problem is that you don't have many roots in the soil because of the thatch.

I would say core aerate as soon as possible/recommended time for KBG. (I'll let the KBG pros take this one)

Have your soil tested for pH, NPK and organic material, correct as needed.

As for watering: 3/4 inch of water is generally sufficient. (do the tuna can test to determine amount) Do not water the lawn again until signs of wilt occur again. This technique works regardless of turfgrass species/soil type. It may take up to 6 weeks to condition your turf to survive several days or more without wilting between irrigations or rainfall. During this time the root system is developing and growing deeper into the soil. In time, your lawn will establish a more uniform appearance with less thatch and a deeper root system.

Thanks skoot_cat.....

KBG folks.....dealing with the thatch....what are the feelings about aerating vs dethatching? Seems aerating would be easier on the lawn that is still alive but maybe isn't harsh enough to tackle the problem? Slow and steady approach to fixing this problem or bring on the Armageddon?

I've moved away from the watering every other day schedule (previous years) to only watering once the lawn shows the wilting/purple look (since winter). That may explain why I haven't seen this problem before. The thing that gets me though is this grass didn't turn purple and go dormant....it just died! The leaves come off in your hands as you run your fingers through it. I would have expected to see some kind of sickly period when the plants would be begging for food/water.

Aerating will certainly help the thatch problem and increase water/nutrient penetration. It'll lift the soil cores and send them into the thatch layer, helping it decay.

I think you'll be happy with the result from aeration or dethatching, but if your soil is compacted, aerate instead.

Again, it's a fall/spring sort of thing, so it can't be done until the weather breaks or very close to it. Post-August 15, although I don't know your weather. You can also seed immediately thereafter as the aeration holes will give it a good start.

Thanks morpheus...aerating was already on the agenda for sometime after Labor Day. This will make it a higher priority.

So is there nothing that can/should be done at this time? Or just let things go and wait for rehab time come fall?

"what are the feelings about aerating vs dethatching?"

Since you have both a thatch and a compaction problem, I suggest that you dethatch and core aerate. You'll get better tine penetration when you core aerate if you dethatch first.

-Deerslayer

Thanks morpheus...aerating was already on the agenda for sometime after Labor Day. This will make it a higher priority.

So is there nothing that can/should be done at this time? Or just let things go and wait for rehab time come fall?

Fellas -

The more research I do, the more I think this is Summer Patch.

{{gwi:1104019}}

Via K-State's Dept of Plant Pathology. The way it showed up is similar to the disease's development cycle and the dark decaying roots and no sign of leaf damage all make this a leading contender.

Just a thought on the thatch issue -- I have a dethatching rake that I bought at the local farm & home store - though I hear you can get them at Lowes, etc. While I would certainly avoid a power dethatching or aerating until cooler weather, I use my rake throughout the summer on small spots. I started off this year with a HUGE thatch problem, and am still fighting bits of it here and there. I have just tackled my issue with the rake and compost tea. I find the rake works well for SMALL areas (10'x10' for example) and does not stress the lawn enough to create a problem, even in 90+ degree weather. I find that it allows me to remove enough of the thatch to allow the water to penetrate, but leaves enough there to help protect the grass. The rake was $30 and worth every penny.

Just a follow up to put this thread to rest and to maybe help someone who stumbles upon this thread while looking up KBG and summer patch, I sent a sample in to the Univ of Missouri to have things tested to make sure. Below is the text of the findings....no surprises.

Diagnosis

summer patch

The submitted grass had a lot of discolored and decaying roots. It appears the decay and

discoloration is leading to the damage to the turf. We were able to find fungi associated

with the roots that is consistent with Magnaporthe, the fungus that causes summer patch.

Please see attached information on summer patch. The soil associated with the roots was

a very heavy clay. This heavy soil may not drain very well and contribute to the problem.

During your current renovation, you may want to consider organic amendments to

improve the soil quality. In addition, the thick layer of thatch present may contribute to

problems. In the future, more frequent dethatching may help prevent excessive thatch

build-up. If you have additional questions about the sample, please contact us.

Rob

Thanks for posting the results from the University of Missouri. Like you indicated, it may help someone else in the future.

I think my diagnosis might have been summer patch if I saw your last picture first. The distinct lines in the first picture confused me. Perhaps your mower wheels initially spread the fungus in lines.

-Deerslayer

I first sent digital photos to Missouri and spoke with the lab tech to see if they could diagnose from the pictures. He did say summer patch then but I pressed that they do the testing to make sure since I'm doing a full renovation this fall and I wanted to know for sure what to attempt to prevent next year. He said that the heavy rains this spring followed by the heat we had was enough to push some lawns over the edge and cause the outbreak of summer patch they are seeing. He said that matting caused by the wheels when I finally got to mow after a week of rain (already at the highest setting on mower so it was brutal) that was just enough to trigger the fungi.

Thanks for the detailed explanation.

-Deerslayer