Small (about the size of my palm) dead patches are developing all over our backyard lawn. The grass in these dead patches does have a reddish tint in some blades.

We purchased this house last fall, so this is our first summer with the lawn. We have an irrigation system, and have it set to water the area in the early morning 3x a week, and leave the grass long when we mow. I did fertilize with Scots turfbuilder in March. We had the lawn aerated this spring as well.

Does anyone have an idea on what might be causing these spots, or what I should do to try and fix the lawn?

thank you!
Michelle

Do you know what kind of grass you have? What has the weather been like in eastern WA?

thanks!
Michelle

Here is a link to the photos I took this morning. I'm not sure how to include it so hopefully I do it right! :)

In the photos, the disease appears to be spreading, so treat your entire lawn.

Whenever I see dollar spot, I immediately think of a lack of nitrogen. However, this is not the time of year to be applying nitrogen to your lawn....it's too hot. Just live with it for now, and be ready to apply nitrogen in mid-late September.

Have you done a soil test?

mpg2004, your grass looks quite yellow for even this time of year. Did you use the Scott's at the bag rate?

With the inspection you did, the redness, and the rainfall, the fungus diagnosis sounds most plausible. If you are cool enough to use the Immunox that is the best chemical solution. If you are on an organic program, there is no solution I know of that works on red thread or rust. For other diseases, corn meal works reasonably well, but not for the red ones.

I'm going to guess that your lawn is perennial ryegrass. That is the predominant turf in the PNW.

When you take your pictures, please try to take them when the Sun is low or a cloud goes by. You don't want harsh contrast in a grass picture.

I just applied 50 pounds of corn meal on my lawn in San Antonio. We're about 3 weeks past the last heavy rain and there are spots all over the grass. I've not seen it this fully covered with disease.

I have another bag I'm going to apply in George West. I have a giant fairy ring in the front yard. It is so big I could not see it until Google Earth updated their imagery this past April.

1) Will the brown grass come back and turn green again or will I have to reseed those areas to prevent crab from growing?

1b) What else should I do to it and when? Fertilizer? Turfbuilder? Aerate? Dethatch? Do I NOT TOUCH IT for the next month while the fungicide works its magic?

2) Do the fall "Winterizer" fertilizers have nitrogen in them? If so, I always apply the Scott's burgundy bag of Winterizer fertilizer in the fall. This past winter in Detroit was VERY warm though... Never really got below freezing, so I don't think the grass every really totally hibernated (??). That's probably why half the lawns in my subdivision have this same issue... just not as bad as I do!

Thanks again!!!

1b. The answer to these issues depends on the results of a soil test. Get the soil test done at Logan Labs, then post the results here for interpretation. Other than applying the Immunox, and watering correctly, don't do anything else until cooler weather arrives. I would advise you not to mow during this hot spell.

2. Yes, the Scotts Winterizer material contains nitrogen.

Thanks!

Winterizer is designed to provide a heavy dose of N, so that's what it does. Last winter might have been a fluke, though, where the N got used in the warmer conditions. Normally 2/3 of the annual N goes down in fall. The "normal" way to do that is to apply one dose in late spring after the main flush of grass growth is over (remember Memorial Day). Then apply another dose after the summer heat breaks (remember Labor Day). The winterizer goes down in mid to late fall (Thanksgiving). These dates are easy to remember but might not apply the same to someone in Miami as well as someone in Green Bay.

You do not need to dethatch. Thatch comes from frequent fertilizer and daily watering. That is not you.

You do not need to aerate. Aeration brings up weed seeds you do not need. If your soil seem to be hard even after watering, then you can spray it with clear shampoo to help the water penetration.

If you want to fertilize now, you can do that with organic fertilizer, not chemicals. Organic fertilizer can go down any day of the year.

two more quickies:

1-i sprayed the immunox down on Aug 1. how much should i be watering between then and my next immunox treatment on Aug 15 ?

2-when should i start seeing results/when will i know its working?

3-(i lied, one more) any idea where to get a soil test done in metro detroit? just get a HD kit? or is there a special place i shouls go?

thanks again!

2. I would think that you would start seeing green grass shoots in the brown areas 7-10 days after the application.

3. Submit your soil sample to Logan Labs in Ohio. Look them up on the internet for their information. Lots of people on this site use them for soil testing. The cost per sample is $20 and turnaround is approximately 3-4 days.