Is this a fungus?
Hi--I have been trying unsuccessfully to eradicate this problem with my lawn for the past 5+ years to no avail. I have been told that this is "brown spot" by various lawn care companies and have aggressively treated my lawn for that condition with no sign of improvement. My lawn looks perfect in the spring until about the second week of July every year then these dead spots appear in nearly exactly the same location every year. I have been using Scott's Fungicide several applications each summer and it has not made any difference. This year upon the Scott Company recommendation, I started application in mid-June before symptoms appeared and it did not make any difference. OI have also tried "Heritage" Fungicide ($$$$) and that did not help either. My neighbors have not had this problem in their yards and we have the same type of grass. Any suggestions you could provide to help beat this scourge would be greatly appreciated. Yes. I have carefully reviewed the information on your website trying to nail down exactly what this problem is. . .
Dakota County Minnesota
I believe your lawn is suffering from Dollar Spot. Your description of when it starts to appear coincides with this fungus. It starts when evening temperature are 50 or so and get progressively worse as the weather warms. Our bluegrass is susceptible as is ryegrass. Also it seems that adding more nitrogen (but in granular form) helps to prevent it along with the chemical pre-treatment. The time of day when you water and how often you water play into this also. Stressed grass tends to develop Dollar Spot. Please read through this article from Extension University of North Carolina. It has the most thorough information of any I was able to find. If you follow all the directions and it still returns I would be tempted to remove the grass, amending the soil and tiling and then sodding or seeding. That is not the recommended cure but sometimes we get desperate. Good luck. https://www.turffiles.ncsu.edu/diseases-in-turf/dollar-spot-in-turf/
Thank you for your response. I read through everything you sent and went to the suggested sites and what I am left with is to be more aggressive with the fungicide and to fertilize more often with a granular fertilizer. I have been using a 19-19-19 balanced fertilizer and it seems to work well on the rest of the yard that is not impacted with this disease.
My yard is just under an acre so I am somewhat reticent to plow the entire yard under, supplement the soil, then replant. One of the problems with living in neighborhoods is that the builders strip all of the topsoil off and sell it before putting in houses and leave us homeowners with grass on top of clay to deal with.
Any other suggestions you could offer to rid me of this recurring damage would be greatly appreciated! I am also curious why the spots appear in nearly the same spots every year and don't seem to spread much.
You could try roughing up those areas and mixing in good compost. Your under layer of soil probably is not the same over the entire yard for exactly the same reasons you suggest...stripping off topsoil and then just leveling off with whatever fill they use. The compost will help enriching the soil in those areas combined with the fertilizer. The balanced fertilizer you are using is only for newly seeded lawns. It actually is against the law to continue to use them on your lawn. That is why you will see a lawn fertilizer that reads 30-0-15 for example. http://www.mda.state.mn.us/phosphorus-lawn-fertilizer-law The first number is the nitrogen which will help with your problem.