That looks like "summer patch" we had it back in 2007 has the classic Frog eye look int he brown patches

@Lisa how did you resolve or prevent it following years? Did you rely on fungicide application?

Well, brown patch doesn't affect KBG, and summer patch doesn't affect fescue, so if we knew what kind of grass you have, we could narrow it down. Most likely culprit is lack of water.

I have a mix of kbg/fescue. I was putting an inch of water per week and last year was hot as usual but we had more rainfall than usual.

Hi, That was the year we took the whole lawn out it was really bad, and we sodded the entire lawn in October

Starting over is not an option at the moment. How do you differentiate lack of water vs. some sort of fungus? I'm not convinced that this was due to lack of water.

You need to look closely at the blades. If it's a fungus you will see small lesions on the grass blades. Search Google images for brown patch and compare those pictures to you own grass and see if it looks similar.

Unfortunately, I dont recall if there were any lesions on the grass blades last year and dont have a close up picture of the blades. When I google pictures of brown patch and other fungus, it kind of looks similar to what I have above. If this is fungus and not a water issue, should I take preventative measure by applying fungicide in late May/early June?

If you keep a close check on your grass you should be able to catch a fungus in the very early stages and stop it with fungicide if necessary. Without knowing for sure if it was a fungus or drought issue and without close up photos it's really impossible to correctly diagnose now. I would study up on fungus and what it looks like and regularly inspect your lawn and if you see anything suspicious post a couple good photos here to be identified. I really don't like using a fungicide if it's not absolutely necessary.

I water efficiently and infrequently

What exactly does that mean? You should be watering about .75" every 3-4 days during peak summer.

I would like to know more about the watering schedule. I suspect from the way the original post was worded, the OP reads a lot here. I disagree that .75 inches every 3-4 days is the right amount of water. I have a friend in Phoenix who waters on that schedule but only after the temps get above 110 degrees. Below 110 degrees he waters .75 inches every 5 days and below 100 he waters 1 inch every 7 days. I'm pretty sure living in the Garden State the OP would not need to water that frequently.

I have a friend in Phoenix who waters on that schedule but only after the temps get above 110 degrees.

I bet your friend in Phoenix isn't growing a cool season grass though. I'm not sure what correlation you can make between the drought tolerance of a warm-season grass in Phoenix to the drought tolerance of a cool season grass in NJ. Their ability to photosynthesize is different, their evapotranspiration rate is different, root development is completely different. It stands to reason that the watering schedule is going to be very different as well.

I'm going to bet 99% it was fungus. We got slammed with it here in NJ last year and I lost small sections of my lawn. I'm hitting it hard with fungicides this year to see what happens. Every year my lawn is gorgeous dark green this time of year and it slowly browns out as summer begins with "sustainable" levels of die off due to fungus, I believe.

My watering schedule has been:
Temp in 90's : 1 inch a week (all at once)
Temp in 80's: 1 inch every 2 weeks - sometimes 1 inch in 1.5 weeks if its consistent high 80's.

@danielj_2009 Same, my lawn is nice and luscious this time of year and then around summer it starts to give out no matter how much water i get down. Last year was really bad where a huge portion of it just gave out as you can see in the picture. What kind of fungicide are you planning on using and around what time?

To be honest I've got to look at the bag as I only used it once and too late last year. There is lots of info on fungicides in this forum but I'll let you know what I have. Just be aware that I haven't really even used it and found it to solve the problem yet. There is also an issue of the fungus becoming resistant so you have to change up what you use periodically throughout the season.

My lawn has done exactly what daniel described. Last year I finally
diagnosed the fungus and started treatment before the hot and dry part
of summer.

Last year I used Propiconazole which cleared the
fungus up. Once the the drought hit my lawn went dormant and turned
brown however for the first time it greened back up as soon as we got
rain. This year I will again be using Propiconazole but also will use
Azoxystrobin every 3rd app to avoid resistance. The Propiconazole is
much cheaper. I have already done 2 treatments because there was already
some fungus showing up but as of this weekend seems to be under
control. My lawn is 14.5k so I use a 31 gallon pull behind sprayer to
put it down.Here's a picture from a few weeks ago to give you an idea what the fungus looks like. You can see the lesions on a few of the blades.

Also, just FYI, it looks like Scotts released a new fungus control product containing azoxystrobin called DiseaseEx. Covers up to 5,000 sq ft. So if you don't want to drop big bucks on concentrate, there's another option now.

Forsheems, what azoxystrobin product are you using? Would you be interested in splitting a gallon of Abound?

I'm using Prime Source Azoxy 50 WDG from domyown.com. If it works out as planned I should be good for this year.

Thanks for the tips! If I can get a small bottle of propiconazole, then I'll probably go with that.

I plan on putting down milo around late Memorial Day - Should I be aware of any fungicide and fertilizer interactions?

The mix rate for the Propiconazole for most fungus diseases is 1 to 2 ounces per 1k so depending on how big your lawn is will determine the size bottle you need. As far as I know there are no interactions between fert and fungicide but either way I would allow at least a week between applications.

I have had really bad fungus problem this past few years, the fungus take over my all backyard around 8000Sqft. I have never applied any fungus treatment. I have a 4 years old boy that love to run and play in the backyard. will it be safe to apply the new scotts product diseaseex has a preventive treatment knowing that i have small kids running around ? how many pound a sqft do you guys recommend? when do you guys

@pelouse77

DiseaseEx will be fine around kids, it goes into the ground and the grass takes it up through the roots. You will have to read the instructions on the bag to determine how many pounds per thousand sqft. Keep in mind, it's not a once and done, you will need to apply it every 2-4 weeks through summer.

You should start applying as soon as temps start to hit the 80s consistently.