Ongoing Issue With Discolored Lawn

Question: Hello. For several years, a portion of our lawn starts out the spring practically white in color, and then it greens up over the summer (see attached photo). I think the affected area has grown a bit each year. Some lawn services have suggested we have grubs, and we did get one treatment last spring, but it didn't help. What do you think it is and how should I treat it? Thank you!

responder: MJ Replied April 21, 2023, 5:24 PM EDT
response: Hi Andrew, This almost looks like heat stress. Do you water the grass? We had a drought last year, and this area is on a slope in what looks like full sun. Heat from the sidewalk and cutting the grass short in summer could compound the issue. If you water, what time of day do you do that? If the grass greens up in spring, does it look normal for awhile and then begin to brown? When does that happen? Do you fertilize the lawn, or use salt on the sidewalk in winter? This U of M page may be helpful: https://apps.extension.umn.edu/garden/diagnose/plant/turf/index.html With grub damage the lawn often dies and when you pull on grass stems the sod will lift off the ground because the roots are so damaged. Information on grub damage to lawns, and treating for that is here: https://extension.umn.edu/yard-and-garden-news/fall-turf-grass-problems-grubs-might-be-culprit If you can answer the questions above we might be able to narrow down the possible causes.

responder: The Question Asker Replied April 28, 2023, 4:28 PM EDT
response: Thank you for your response to my inquiry. For the past two years we've hired a lawn service, so the lawn has been well-fed. I water as needed, and I can't see why this specific area would be more prone to sun damage than others. We had a grub treatment last spring in case that was the problem, but it seems to me the lawn would be in worse shape if we've had grubs for several years, and I've never seen birds feeding there. My recollection is that the area greens up in springtime and pretty much matches the rest of the lawn until the snow melts the following year. The blades look white and dried up, not rusty, and it's this entire section, not patchy. Could there be something underground that is harming the grass in this area? I can't imagine what that would be if not grubs. The area is gently sloped to the north, but so are other areas that are not affected.Would it help to take a soil sample and have it analysed? Do you have any other recommendations?Thanks again for your help.~AndyOn Fri, Apr 21, 2023 at 4:24 PM Ask Extension <<personal data hidden>> wrote:

responder: MJ Replied April 28, 2023, 5:32 PM EDT
response: Hi Andrew, Thanks for the new information. I’m not sure what’s going on here, but I do think this is an environmental condition rather than disease. As you said, the grass is alive and eventually turns green every year. To me your grass looks like some of the pictures on this website about Kentucky bluegrass and drought: https://extension.umn.edu/yard-and-garden-news/allow-some-browning-lawns-conserve-waterIt may be wise to seek a soil test to see if there is something in the soil that could be affecting the lawn. Also, in urban areas it’s not uncommon to find strange things underground, including gravel, construction debris and in my own case paving stones that were buried four inches under one area of grass! Something like that could affect drainage or moisture retention. Soil tests that you buy in stores are unreliable, so my advice would be to get your soil tested at the University of Minnesota Soil Testing lab. It will cost $19. You can find forms and more information here: https://soiltest.cfans.umn.edu/The lab is in St. Paul. On the forms you can download from the website tell them your concern is about the lawn and this annual spring condition. The website explains how to take a sample. I hope you get some answers! Thanks for using Ask Extension.

responder: The Question Asker Replied April 28, 2023, 5:45 PM EDT
response: Thank you for your help!  ~AndyOn Fri, Apr 28, 2023 at 4:32 PM Ask Extension <<personal data hidden>> wrote:

responder: MJ Replied April 28, 2023, 5:51 PM EDT
response: Good luck!