I was going to say shade as being the main factor, based on the first pics... but that last one with the long bare area doesn't fit that profile. I'm also doubtful that it's a nutrient deficiency or anything that a standard soil test would pick up .. would be curious to find out the results. I'm wondering if nematodes or other such microbiology may be the culprit?? Tagging @Greendoc in case he may be of assistance on this Emerald Zoysia lawn.

 

Strictly a guess, but could drainage be an issue here? Are these areas flooding with standing water? The shape and location looks like its in the bottom of slopes from the landscaping and between the tree mulch and walkway. The spot between the tree and the bend in the walkway in the bottom picture looks like it could be washout from water running down the walkway and getting trapped by the tree rise, and then it starts flowing down which could create that shape in the picture.

Does zoysia die off or develop some sort of root rot with excess water areas?

 

Based on the top 80% of the second pic, it almost looks like it could be due to streaming water. But if that were the case, then I wouldn't expect the stream to neatly cutoff toward the bottom of the photo.

I'm a lawn care noob, though, so maybe I'm totally off, but the abrubt nature of the path almost seems like it would be related to a machine that was run in that area. Gasoline? Scalping?

But that wouldn't explain why it *continues* to happen even after resodding. :?

 

Drainage issues, perhaps with some shade issues thrown in to complicate it.

 

Curious to see what's happening when it rains heavy, looks like drainage issues from sidewalk and pine needle mulch. Throw in some shade in there too. I'll also throw in the pine needles because they are horrible and I can't stand them one bit. I burn and bag a crap ton of pine needles yearly, It's baffling to me that people pay for these for mulch. Just come to my yard. Rake em up and have them! :lol:

 

Strictly a guess, but could drainage be an issue here? Are these areas flooding with standing water? The shape and location looks like its in the bottom of slopes from the landscaping and between the tree mulch and walkway. The spot between the tree and the bend in the walkway in the bottom picture looks like it could be washout from water running down the walkway and getting trapped by the tree rise, and then it starts flowing down which could create that shape in the picture.

Does zoysia die off or develop some sort of root rot with excess water areas?

I talked to the homeowner and asked do these areas flood when we get a heavy rain. He said they do not. Two of the three bad areas are up near the top part of the yard that is higher in elevation. Doubtful water could even pool in those spots.

 

Curious to see what's happening when it rains heavy, looks like drainage issues from sidewalk and pine needle mulch. Throw in some shade in there too. I'll also throw in the pine needles because they are horrible and I can't stand them one bit. I burn and bag a crap ton of pine needles yearly, It's baffling to me that people pay for these for mulch. Just come to my yard. Rake em up and have them! :lol:

The areas do not flood when a heavy rain occurs. It's really weird. I'm considering getting a probe and probing these areas to see if there is something underneath the surface.

 

@Greendoc, I hear you are the Empire expert. What say you?

 

Another bit of info that is puzzling. The homeowner overseeds with Rye every fall. He said the Rye fills in these areas and thrives in the whole yard. Said he never has a problem with the Rye. But the Empire dies in these same spots everytime he gets them re-sodded.

 

that's a nice looking sidewalk. It's weird that the patch is about as wide as a sidewalk is. Hmmmm... :?

 

I can't see in the picture well enough, but I was thinking about this. If it's not water that's causing the issue, what about pine needles? All of the discoloration in the pictures is next to the trimming. When it rains, is the water by chance carrying pine needles down into the grass, causing it to slowly accumulate and choke out the zoysia?

So, I was searching for pine needles affecting zoysia and found this.
https://homeguides.sfgate.com/grass-shade-around-pine-trees-56007.html
Pine (Pinus) trees grow in most U.S. Department of Agriculture hardiness zones, but zones 2 through 9 have the most favorable conditions for the different varieties of pine. Kansas is the only state with no native pine trees. With such a wide variety of pine trees adapted to the different regions, the grass growing under the trees also varies according to the weather. Soil conditions under the trees are acidic, and grasses that are acid- and shade-tolerant survive best under the trees if they receive some sunlight and a lot of water.

The last sentence got me thinking, is Rye grass tolerant to acidic soil? Adding on to your last comment about why rye grass grows, I just found this.
https://forage.msu.edu/extension/perennial-ryegrass-potential-in-michigan/
Perennial ryegrass grows best on fertile, well-drained soils but has a wide range of soil adaptability. It is tolerant of poorly drained soils and frequently is used in these environments. It tolerates both acid and alkaline oils, with a pH range of approximately 5.0 to 8.3.

When it's time to do the soil samples, I would take a sample of the problem areas, and take a few of the best growing areas to compare against. I am wondering if either pine needles are working themselves into the ground from runoff, or maybe some of the natural acids from the needles are leeching out during rains and then getting into the lawn and affecting the PH levels to make it not suitable for zoysia, but still fine for rye grass to grow. This would explain why re-sodding of zoysia keeps producing the same results in the same locations.

 

Does the homeowner have any idea what the backfill material is? also...

that's a nice looking sidewalk. It's weird that the patch is about as wide as a sidewalk is. Hmmmm...

^^Interesting observation right here.^^ Was there originally a sidewalk there, it got busted up with a sledgehammer, left most of the concrete in place, and covered with dirt?

The first pic, I can't see what is to the right, but the mailbox area has two crepe myrtles. If there is another one in the bed to the right, those roots will do some strange things. That area near the mailbox might just be overrun with crepe myrtle roots.

 

I can't see in the picture well enough, but I was thinking about this. If it's not water that's causing the issue, what about pine needles? All of the discoloration in the pictures is next to the trimming. When it rains, is the water by chance carrying pine needles down into the grass, causing it to slowly accumulate and choke out the zoysia?

So, I was searching for pine needles affecting zoysia and found this.
https://homeguides.sfgate.com/grass-shade-around-pine-trees-56007.html
Pine (Pinus) trees grow in most U.S. Department of Agriculture hardiness zones, but zones 2 through 9 have the most favorable conditions for the different varieties of pine. Kansas is the only state with no native pine trees. With such a wide variety of pine trees adapted to the different regions, the grass growing under the trees also varies according to the weather. Soil conditions under the trees are acidic, and grasses that are acid- and shade-tolerant survive best under the trees if they receive some sunlight and a lot of water.

The last sentence got me thinking, is Rye grass tolerant to acidic soil? Adding on to your last comment about why rye grass grows, I just found this.
https://forage.msu.edu/extension/perennial-ryegrass-potential-in-michigan/
Perennial ryegrass grows best on fertile, well-drained soils but has a wide range of soil adaptability. It is tolerant of poorly drained soils and frequently is used in these environments. It tolerates both acid and alkaline oils, with a pH range of approximately 5.0 to 8.3.

When it's time to do the soil samples, I would take a sample of the problem areas, and take a few of the best growing areas to compare against. I am wondering if either pine needles are working themselves into the ground from runoff, or maybe some of the natural acids from the needles are leeching out during rains and then getting into the lawn and affecting the PH levels to make it not suitable for zoysia, but still fine for rye grass to grow. This would explain why re-sodding of zoysia keeps producing the same results in the same locations.

Great information. I told him to get soil samples from the problem areas as well as the areas that grow well. Very interested in seeing the results.