Irrigated lawn turning brown in August - Ask Extension
We planted a lawn last October. It was green and full most of the summer, then it started to develop brown areas in mid-August. It is irrigated. Do yo...
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Irrigated lawn turning brown in August #808414
Asked August 28, 2022, 5:30 PM EDT
We planted a lawn last October. It was green and full most of the summer, then it started to develop brown areas in mid-August. It is irrigated. Do you know what is happening and how to improve it?
Kent County Michigan
Expert Response
I need to ask a few questions for more information:
When do you water (what days, time of day)? How much each time?
Did you do a soil test as part of the seeding process, if yes what is the access code (so I can understand your soil nutrition status)?
When do you fertilize, with what kind of fertilizer, how much is applied per 1000 sq ft?
What turfgrass species did you plant?
Please describe the steps in your seeding process.
Is the lawn sunny or shaded or a mix of both?
Have you had a grub problem in the past few years?
Have you used weed killer and/or grub control products since seeding, if yes when?
I suspect that you may have a summer turf disease (brown patch?, summer patch?), but need the answers from your questions to help diagnose it.
I am attaching links to info on turf diseases for you to review:
MSU Turf disease ID
Purdue turf disease ID
Turf Diseases & Pests-PSU
There might be a grub problem as now is the time newly hatched grubs are feeding on turf roots. Check for grubs as described in this link (they will be small): How to Choose & Apply Grub Control Products-MSU
Send me a return email with your answers to my questions and I'll send you back a reply.
When do you water (what days, time of day)? How much each time?
Did you do a soil test as part of the seeding process, if yes what is the access code (so I can understand your soil nutrition status)?
When do you fertilize, with what kind of fertilizer, how much is applied per 1000 sq ft?
What turfgrass species did you plant?
Please describe the steps in your seeding process.
Is the lawn sunny or shaded or a mix of both?
Have you had a grub problem in the past few years?
Have you used weed killer and/or grub control products since seeding, if yes when?
I suspect that you may have a summer turf disease (brown patch?, summer patch?), but need the answers from your questions to help diagnose it.
I am attaching links to info on turf diseases for you to review:
MSU Turf disease ID
Purdue turf disease ID
Turf Diseases & Pests-PSU
There might be a grub problem as now is the time newly hatched grubs are feeding on turf roots. Check for grubs as described in this link (they will be small): How to Choose & Apply Grub Control Products-MSU
Send me a return email with your answers to my questions and I'll send you back a reply.
Dear Dick,
Thank you for reviewing my question and photos.
1. I water before sunrise for 5 minutes every 2 days. Specs are about 2 inches/hour, or 0.17" per session but I have not measured it myself.2. Soil test is pending (mailed 8/29)
3. I have not fertilized since the lawn was seeded last fall
4. Landscaper has a custom seed blend for shade so I don't know what's in it. I will ask them.
5. It was seeded and mulched (grey water absorbent pellets) last autumn
6. Lawn is mostly shaded under a large white oak. The sunnier areas don't have brown patches.
7. I checked a few affected areas for grubs and didn't see any. The area never had a lawn before so I wouldn't know if grubs were in my yard last year.
8. I have not used any weed killer or grub control products
9. I mow it pretty long
It looks like the photos of summer turf disease to me.
Thanks,
Dan
Thank you for your answers. Watering is about 0.5-0.6" per week, which is about half of the 1" per week a lawn likes. I would also suggest delaying watering until after sunrise to reduce the time leaves are wet (which can promote diseases). A key is in #6 above that sunny areas aren't brown but shaded are. It could be that the sunnier grass species are going dormant (or dying) in the shade, made worse by the dryness and summer heat of August weather. It also could be lack of water under the tree canopy as trees are voracious consumers of water. Excess N isn't a problem. You could apply 0.5# N per 1000 sq ft this month.
I'm curious to learn what the soil test will tell us about your soil so we can learn if anything needs to be done to improve turf health.
The photos don't give enough detail to determine if it is a summer turf disease. I'm attaching links to ones I suspect may be the problem. You will need to read about the signs and look to see if you can find them in your lawn.
https://extension.psu.edu/turfgrass-diseases-brown-patch-causal-fungus-rhizoctonia-solani
https://www.canr.msu.edu/ipm/diseases/brown-patch
https://extension.psu.edu/turfgrass-diseases-summer-patch-causal-fungus-magnaporthiopsis-poae
https://www.canr.msu.edu/ipm/diseases/summer-patch
These are the 2 diseases I think are most likely, but you should check out these other summer turf diseases on the links I sent you in the first email as well: Dollar spot, anthracnose, grey leaf spot and summer leaf spots.
Another option is to contact MSU Plant & Pest Diagnostics as they have more depth of experience to ID a disease than myself. Go to: https://www.canr.msu.edu/pestid/ Please email me with their diagnosis if you contact them so I can learn too.
I'm curious to learn what the soil test will tell us about your soil so we can learn if anything needs to be done to improve turf health.
The photos don't give enough detail to determine if it is a summer turf disease. I'm attaching links to ones I suspect may be the problem. You will need to read about the signs and look to see if you can find them in your lawn.
https://extension.psu.edu/turfgrass-diseases-brown-patch-causal-fungus-rhizoctonia-solani
https://www.canr.msu.edu/ipm/diseases/brown-patch
https://extension.psu.edu/turfgrass-diseases-summer-patch-causal-fungus-magnaporthiopsis-poae
https://www.canr.msu.edu/ipm/diseases/summer-patch
These are the 2 diseases I think are most likely, but you should check out these other summer turf diseases on the links I sent you in the first email as well: Dollar spot, anthracnose, grey leaf spot and summer leaf spots.
Another option is to contact MSU Plant & Pest Diagnostics as they have more depth of experience to ID a disease than myself. Go to: https://www.canr.msu.edu/pestid/ Please email me with their diagnosis if you contact them so I can learn too.
Here is info on my soil test results:
Dear Daniel Fechtner,
Your Lawn MSU soil test for your back field is ready. Click the link below to
view it:
https://homesoiltest.msu.edu/your-results/code/GTYAV9
If you have any difficulty with the link, you can use the following code on
the website:
GTYAV9
Thank you,
MSU Soil Test Team
Your Lawn MSU soil test for your back field is ready. Click the link below to
view it:
https://homesoiltest.msu.edu/your-results/code/GTYAV9
If you have any difficulty with the link, you can use the following code on
the website:
GTYAV9
Thank you,
MSU Soil Test Team
Your soil test shows your soil is low in Potassium (Potassium promotes resistance to disease, drought, cold and heat damage). MSU recommends adding 1.6# per 1000 sq ft. You can use a winter fertilizer as suggested in the soil test report or a general fertilizer like 12-0-12 or 10-0-10. Apply no more than 1.0# N per 1000 sq ft of the general fertilizer and you'll add the same amount of potassium. Be sure to water it in. Add the balance next year.
You may also be low in Nitrogen since you haven't fertilized since seeding which can also lower turf resistance to diseases. The recommendation for potassium will apply to N if you use either one of the above general fertilizers. No more than 1# N per 1000 sq ft should be applied. Some turf diseases have more effect when the pH is alkaline (above 7.0) but I see that MSU did not recommend lowering the pH in your soil test report.
I do not have enough detail to determine the exact turf disease you have. I suspect summer patch, dollar spot and grey leaf spot, so check those diseases out looking for the leaf symptoms in your turf as described in the links I sent you on 8/30/22.
I wonder if drought stress (under the tree) is part of the problem as you said there are no brown spots in the sunny areas. I'd fertilize the yard to add needed nitrogen and potassium, water it in and see what happens this fall.
You may also be low in Nitrogen since you haven't fertilized since seeding which can also lower turf resistance to diseases. The recommendation for potassium will apply to N if you use either one of the above general fertilizers. No more than 1# N per 1000 sq ft should be applied. Some turf diseases have more effect when the pH is alkaline (above 7.0) but I see that MSU did not recommend lowering the pH in your soil test report.
I do not have enough detail to determine the exact turf disease you have. I suspect summer patch, dollar spot and grey leaf spot, so check those diseases out looking for the leaf symptoms in your turf as described in the links I sent you on 8/30/22.
I wonder if drought stress (under the tree) is part of the problem as you said there are no brown spots in the sunny areas. I'd fertilize the yard to add needed nitrogen and potassium, water it in and see what happens this fall.
