What could cause this pattern of dead grass

2418 Views 35 Replies 15 Participants Last post by tommydearest, 12 d ago

tommydearest

Discussion Starter · 7 mo ago

2

Mower just got done with lawn. I've noticed this lined pattern of dead-ish grass after he was done. Now, if he had mowed too low, I would assume the entire area would be this color. I thought there may have been some grub damage because I saw a LOT of birds in this area over the summer. But, why would there be solid lines of green matching the mowing tracks?

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collinskl1

· #2 · 7 mo ago

Is the area flat? The tire tracks could be lower than the other areas, so the grass it taller there.

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tommydearest

Discussion Starter · #3 · 7 mo ago

I lean towards grubs mainly because I put down grub killer in the area highlighted in this pic. That is right around where these lines of dead grass stop. But, those lines of dead grass don't seem to pull up like carpeting, as my grub damage in front did.

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tommydearest

Discussion Starter · #4 · 7 mo ago

collinskl1 said:
Is the area flat? The tire tracks could be lower than the other areas, so the grass it taller there.

It's slightly graded away from the camera position. The greener lines seem to be cut at about the same height.

tommydearest

Discussion Starter · #5 · 7 mo ago

Actually, @collinskl1 I went out and "wiped" the green grass, like you would a suede couch, and sure enough it is somewhat taller.
Now, here's my quandary. The brown grass seems to be rooted just fine but the green longer grass seems pull out very easily, almost like carpeting. I don't want to start pulling it out.

Anyone? Best course of action? Is it too late in the season to really affect the grubs, if that's what it is? Should I just plan on getting 24 hour killer out there early next season?

I just don't get why the brown grass seems to be rooted much better than the green.

jha4aamu

· #6 · 7 mo ago

Does he mow in the same pattern each time? Likely the tire tracks have created ruts and in the middle of the pass the mower deck is lower and cutting the grass lower, or scalping it.

Def not grubs though. They dont eat in straight lines.

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tommydearest

Discussion Starter · #7 · 7 mo ago

jha4aamu said:
Does he mow in the same pattern each time? Likely the tire tracks have created ruts and in the middle of the pass the mower deck is lower and cutting the grass lower, or scalping it.

He does. Can you think of a reason why the grass that grows in those ruts would stay green but pull out so easily?

kdn

· #8 · 7 mo ago

tommydearest said:
He does. Can you think of a reason why the grass that grows in those ruts would stay green but pull out so easily?

Water pools in the ruts so the roots don't go looking deeper?

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tommydearest

Discussion Starter · #9 · 7 mo ago

kdn said:
Water pools in the ruts so the roots don't go looking deeper?

Seems like a pretty logical theory, but I can't find anything online that addresses that. We walk through our yard a lot and never notice any sort of soggy areas. If the pooling was happening, wouldn't we notice that?

Does lead me to another theory, would the compacted soil keep roots shallow? I just can't find anything mentioning shallow roots with mower ruts.

macattack

· #10 · 7 mo ago

What is the HOC anyways? Looks like matted grass in the ruts and scalping the in between area. Alternate pattern and maybe raise HOC a notch.

tommydearest

Discussion Starter · #11 · 7 mo ago

macattack said:
What is the HOC anyways? Looks like matted grass in the ruts and scalping the in between area.

I'm not sure what he cuts it at. I had asked him to raise it over the summer and believe he did. I have a feeling he's lowered it recently.

Think it's around 3" now. I think you're right about the ruts and scalping. Trying to figure out why the matted grass pulls out like carpet.

macattack

· #12 · 7 mo ago

I'd get out there with a ruler to verify grass lengths and mower deck if/when you can. Normally I don't see this in my yard unless I am lowering for dethatch and get to ~2" HOC with my Toro SR. But it looks like a heavier mower perhaps with wider tires. What is doing the cutting? Also probe for moisture with a screwdriver.

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Ben4Birdies

· #13 · 7 mo ago

+1 What kind of mower is being used?

tommydearest

Discussion Starter · #14 · 7 mo ago

Ben4Birdies said:
What kind of mower is being used?

macattack said:
What is doing the cutting?

It's a Gravely zero-turn. Not sure on model or size, but it isn't little.

tommydearest

Discussion Starter · #15 · 7 mo ago

macattack said:
Also probe for moisture with a screwdriver.

I will do this in the morning. Are you thinking the brown areas will be drier than the green areas?

I'm definitely thinking this is because of repeated paths and the mower wheels being lower than the deck. Now, I'm mostly just perplexed why the green grass seems to pull out so easily while the brown grass is firmly rooted. Is the compaction of the soil, by the wheels, enough to make the grass pull out so easily?

tommydearest

Discussion Starter · #16 · 7 mo ago (Edited)

Ok, went out this morning and inspected more. Pulled a couple of plugs and realized roots were probably around 4" in both spots. Soil was moist in both spots.
I was somewhat mistaken when I said the green spots pulled up like carpeting. They were so long that I just thought it was all coming up. This morning, I tugged against the direction they were matted and they just pull up so far, it felt like I was pulling them out by the root. When I tugged in the direction of the matting, they pretty much stayed put. It's folded near the soil so it's almost like expanding an accordion, if you know what I mean.
The browner grass is exactly 3". I'm estimating the matted grass is in the neighborhood of 6" minimum.

So, how do I proceed from here? Looks like a week before warm fall temps are over for good. The only mower I currently have is a manual reel mower with about 2.5" height max. I plan on buying a riding, or zero-turn, this coming spring. Do I just wait until spring to deal with this or is there something I can/should do now?

Thanks for the ongoing help everyone.

An image of the matted spot pulled up

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The Back [yard]9

· #17 · 7 mo ago

tommydearest said:
Seems like a pretty logical theory, but I can't find anything online that addresses that. We walk through our yard a lot and never notice any sort of soggy areas. If the pooling was happening, wouldn't we notice that?

Does lead me to another theory, would the compacted soil keep roots shallow? I just can't find anything mentioning shallow roots with mower ruts.

It’s not going to say tire ruts probably. It’s about the water amount caused by the ruts. The more water the less need to increase depth to look for water. Top dressing to bring ruts to level will effectively increase root depth. He really needs to change pattern to keep from creating too much grain, exponentially increasing fungus and disease pressure/risk.

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ricks

· #18 · 7 mo ago

How long was your grass before cutting it? You have a nice thick lawn too. You're supposed to cut less than 1/3 of the length of the blade to prevent the yellow look also.

tommydearest

Discussion Starter · #19 · 7 mo ago

ricks said:
How long was your grass before cutting it? You have a nice thick lawn too. You're supposed to cut less than 1/3 of the length of the blade to prevent the yellow look also.

I can't be sure of the length before cut. I had asked the guy to cut it longer, throughout summer and early fall, because he only comes once a week. I'm aware of the 1/3 rule and I knew he'd be breaking it, especially during nitro blitz, if he only came once a week and cut at 3" every time. Guessing, I'd say he'd cut at 4". By the time he cut it yesterday, it may have well been 5 to 5-1/2".

I understand all of this, now, and will be taking over mowing duties next season. I just need to know the best way to proceed from here. That matted grass is probably 8" and it's practically folded in half.

macattack

· #20 · 7 mo ago (Edited)

You can use a blower or rake to bring the matted down rut areas to stand up prior to a 45 to 90 degrees cut angle change. A lot of work, but it is what it is. I get this along fencelines where I can't really change path and have to get the rake out. I would assume there is a height difference from the rut to the center, could measure using a 2x4, for information anyways. I try not mowing same directions for 3x, and will alternate pattern. Ruts will naturally hold water. I wouldn't think 3" HOC in the center would cause browning due to scalping effect, but its what the data is showing, since rest of grass plant is actually 6-8". I looked up the Gravely. With rider you are looking at 1000# rolling on the lawn. Only an issue if you repeatedly roll the same path, especially if it's wet and soft.

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