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Kisal
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Dead patch in lawn ... unknown cause

I'm having trouble with a specific area of my lawn. The woman who takes care of my lawn is at a loss, and she's a trained professional. She is very much into organic plant care, and never uses chemicals on my lawn. Needless to say, I haven't a clue about what the cause is. The patch of dead grass is an exact square with perfectly straight edges, almost like someone came along and sprayed it with an herbicide. But there's no reason for anyone to do such a thing.

A patch of the lawn about 4 feet square, between the curb and the public sidewalk, dies. It died last summer for the first time in the 25 years I've owned this place. The area is directly over the drain that connects my house to the public sewer. About 10 or 12 years ago, the city replaced the pipe that actually connects my house drain to the sewer, and replanted grass. All has been fine all these years.

What kind of pictures do I need to post so that the knowledgeable members here can offer me some advice?

When it died last year, I pulled up a couple of 12" square areas (cut through the sod on 3 sides and pulled it up) to check for grubs or other insect problems. There was nothing. Not so much as an earthworm. The soil was like dust, even though I deep water the area regularly twice a week at a minimum.

I originally thought my housekeeper might have been using drain cleaner with too free a hand, so I told her not to use it at all, ever again. She swears that she hasn't, and I haven't seen any in the house, so I believe her.

Over the fall and winter, it greened up again very nicely, but now it's dying again. It's just so strange to me! The lawn on either side of the patch is fine and looks very healthy.

Let me know what kind of pics would help. Close ups, I presume. Anything in particular, though?

One last thought (sorry this is getting so long), my lawn lady and I were discussing this today, and she said the only thing she could think to do is to top dress it with a layer of high-quality topsoil, and reseed it. She says if that dies, then she doesn't know what else to try. Is that what I should do?

Bestlawn
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No, I don't think covering over a problem is going to solve it. If you can't pinpoint a cause for such a thing as this, the first thing to do is have it tested by your extension service [url=https://plant-disease.ippc.orst.edu/clinic.cfm]plant pathology lab[/url]. They will check for pressence of disease/fungus. Locate [url=https://extension.oregonstate.edu/locations.php]your nearest extension office[/url] for sampling information.

That the area is perfectly defined makes me wonder what is going on beneath the soil. You mention the public sewer system, which lets me know there is no septic tank underneath. But still, there has to be something if the lab should find there is no disease present.

It's possible the soil mass has diminished in that area. This can happen if the soil contained too much organic matter because it decomposes in a short time, leaving less soil to sustain plant life since the roots no longer have room to grow.

You scare me to say "I deep water the area regularly twice a week at a minimum." Please explain that statement and tell me if other areas of the lawn receive the same amount of water.

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Kisal
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Bestlawn wrote:You scare me to say "I deep water the area regularly twice a week at a minimum." Please explain that statement and tell me if other areas of the lawn receive the same amount of water.
Thank you for your response, Bestlawn. I've read your posts in response to other members' questions, and I respect your knowledge.

Didn't mean to scare you! :lol: When the weather is dry -- we rarely get any rain from mid-July to mid Sept -- I water the lawn twice a week. If the weather is going to be very hot, I may water more often. I try to water in the morning. By "deep watering," I simply mean that I put about an inch or so of water on the lawn when I water. I don't allow the sprinklers to run for hours on end, nor do I just barely wet the surface. BTW, I'm talking about my front yard, which is on a gentle slope. I use an entirely different schedule for my back yard, which tends to drain much more slowly.

Does that help?

My front yard eventually goes dormant every summer, anyway, at which point I don't bother watering it much at all. I've been told (by one of the Master Gardeners at my local Extension Service) that the reason the grass goes dormant is because it is an old lawn, and the grass that was originally planted has been replaced by native grasses that go dormant when the temperature exceeds 80º. Short of tearing it out and replanting it, which I'm not in a position to do at the moment financially, I just let it do it's thing. I don't see any point in watering dormant plants, other than enough to keep them alive. [img]https://bestsmileys.com/clueless/4.gif[/img]

I'm actually considering 2 possible courses of action: #1) removing the dead grass and as much of the soil as is reasonable, replacing it with a mix of good compost and topsoil, then reseeding; or #2) removing all of the grass along the strip between the sidewalk and curb, adding whatever soil amendments may be needed, and planting low-growing shrubs or a ground cover that will stay within the bounds of the concrete (... I.e. no kinnickinnick, thank you. :lol: )

Does any of that make any sense at all? :lol:

Bestlawn
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Didn't mean to scare you! When the weather is dry -- we rarely get any rain from mid-July to mid Sept -- I water the lawn twice a week. If the weather is going to be very hot, I may water more often. I try to water in the morning. By "deep watering," I simply mean that I put about an inch or so of water on the lawn when I water.

Yes, that helps a lot. And I see you know what deep watering means. I just want you to know that watering during the hot summer months is a little different. That one inch is all the grass needs per week and you'd do it all at once only once a week. For summer though, you want to divide that one inch in half to provide half an inch twice a week to relieve drought stress and prevent heat stress and keep the grass green. During days it is extremely hot (heatwaves), divide the one inch into thirds. Irrigate a quarter inch three times a week. Dividing is to run the sprinklers for half the amount of time it normally takes to provide a full one inch. Or, one third the amount of time. This is to acknowledge the grass becomes overheated/parched just as you and I do. Light sprinklings work out better for refreshing relief. And you want to take rainfall into consideration, too. As you mentioned, you can withold water in summer and let it go dormant.

If you've been irrigating one inch 2-3 times a week, it is too much water and can be the cause of disease if in fact it is found you have one. That much water can also kill the grass. LOL Trust me on that one. It is exactly the reason I became interested in lawn care. That I killed my grass by watering too much is the first thing I learned.

I've been told (by one of the Master Gardeners at my local Extension Service) that the reason the grass goes dormant is because it is an old lawn, and the grass that was originally planted has been replaced by native grasses that go dormant when the temperature exceeds 80º.

Whether the grass has been replaced by native grasses is not something I know or have benefit of sight to dispute. However, I cannot agree with the rest of the statement. All cool season type grasses go dormant in summer if you withold moisture. Actually, I think most of the native grasses are less likely to do that since they (most of them depending on species) are so much more drought tolerant than the cultivated spieces. Nevertheless, dormancy is a survival mechanism the grass plants implement to keep themselves alive when conditions are not favorable - high temps and lack of moisture. So, tearing out your lawn and replacing it would be a waste, as dormancy is inevitable in summer if you don't water it.

1. Organic lawncare is not necessarily failsafe

a) not if the grass got smothered by an application of too much compost or something else. I remember killing a patch with dehydrated manure. That stuff is strong even if you don't apply too much. And blood meal is a great source of nitrogen but will kill the grass if she wasn't careful.

b) not if something applied was not needed or in overabundance. If perhaps she tried to amend the soil to correct for acidity or alkalinity. Lime or sulfur that was not needed can cause nutrient tie up and literally shut the plants down. Or maybe iron or magnesium. Some organic folks I know like using Epsom salts not knowing it adds sulfate and magnesium that the grass probably doesn't need. Makes it beautiful for a few days though. That is before the damage reveals itself.

I just wanted to offer a few examples. It wasn't herbicide your lady used, but ask her what did she do exactly.

2. You can try your #1 option, but I really don't think it will solve your problem because it doesn't define the problem. Until you find out what caused this to happen, it will also happen with the new soil and new growth from seeding. Often times, disease colonizes in the soil. If that is the problem, it will also affect the new soil in time, and the same problem will crop back up next year or a few years. If it's only that the soil mass has sunken, you won't have to replace it, just add to it to build it back up. Your extension service will be able to guide you in the depth of topsoil, subsoil, etc.

Direct your attention to finding out the cause of the problem, then you can determine the best remedy. Speaking of soil amendments in your #2 option, it might be just what the grass needs. A soil test will tell you pH balance and nutrient value, as well recommend whatever amendments are necessary, and your extension service can do the soil test.

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Kisal
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A huge thank you, Bestlawn! This has helped me a great deal! :)

So, what I will do is:

1. Adjust my watering schedule per your advice.
2. Take a soil sample to the Extension Service (only a few blocks away) and have them test it.
3. Amend the soil per their instructions.

So, the final question, then, is do I reseed, or just wait for the grass that's there to regenerate? (That should be helped by the new watering schedule, right?)

The lawn lady just mows my lawn. She doesn't put anything on it, except a moss killer of some sort once every year or two. She offers full yard care, but I can't afford it, so I do everything else myself. I dig out the the weeds by hand. I haven't put anything at all on the lawn for about 15 years, when I decided to fertilize it, and burned the heck out of it (... "Oh, dear! It doesn't look like the fertilizer is coming out of the slot, so I'd better open it all the way!" :roll: :lol: )

It isn't a pampered lawn, but it is as nice as the others on my street, and a lot better than some of them. I'd love it if it stayed green all summer. I'd be the envy of all my neighbors! :lol:

Bestlawn
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Anyone can have green lawn through summer if they water it. It's understandable though if you prefer to save on the water bill.

So, the final question, then, is do I reseed, or just wait for the grass that's there to regenerate?

You really don't have the option to reseed right now. Can't do that until late summer-early fall. Follow your plan 1-3 and see what the soil and diagnostic tests reveal. If overwatering or too much fertilizer is the problem, it will likely come back but will take some several weeks, maybe a month.

Good luck on this and please let me know what the tests say. I'm curious really. If you need to reseed in the fall, feel free to request instructions and seed recommendations. The best time for seeding is between mid-August and mid-September. But you being in the Pacific Northwest, that window can normally be pushed a little, ideally when temps are consistently around 70° (between 65° and 75°).

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Kisal
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I can't reseed now? [img]https://smileys.on-my-web.com/repository/Sad/sad-049.gif[/img]

Last August, I filled and seeded an 8 x15 ft low spot in my backyard, and it's beautiful now. I sprinkled it with water 2 or 3 times a day, but that's not hard for me. I'm retired and home the vast majority of the time. Am I missing some piece of lawn care knowledge again? :(

Bestlawn
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Sounds like you did it right. You seeded in August, kept it moist, and it's fine now.



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