Where do you live?

Lawn pH is okay. Is the pH about 7.5 to 8+?

Have you gotten much rain this year? What about last year?

Do you stop watering and let the lawn dry out after it rains?

Have you ever used a product called greensand? The greensand mineral is called glauconite, so you might have used a separate product with that in it.

Can you post a picture or two? Preferably take pics on an overcast day - One showing big picture and one from about 6 inches away.

I appreciate the reply, dchall. We live up the road in a suburb of Austin. Lawn is ~6,700 sf and when I checked the pH a year ago the readings were a little above 7 up to 7.5.

You know about our rainfall -- infrequent but when we've gotten it it's been heavy. Last half of the summer the lawn has been frequently damp, so I expected an increase in fungus. But the yellowing started in early summer and has steadily spread. Haven't run the sprinklers in quite a while but the (visible) ground is always dry before I water. Except in the dead of summer I can get by with watering once a week -- low emitting rotator sprinkler heads run for up to 2 hours -- about an inch.

Couldn't find greensand in the quantities I need (seven 50 lb bags); was told the primary Texas greensand producer stopped selling it and the stuff from out-of-state was too expensive. On a recommendation I tried lava sand in the spring as a substitute.

I'll post some pictures after the rain passes tomorrow.

I don't remember what John Dromgoole's nursery is called, but if anyone has greensand in bulk, it would be him. That will help with a general chlorosis caused by too much rain, but it won't help with fungal issues. Need pics. My lawn has both the rain induced chlorosis and fungal issues. With Floratam St Augustine the grass keeps growing even with some certain disease, so I'm not getting bare spots, but it doesn't look right. We've had measurable rain 19 of the past 45 days. For us it's crazy.

That nursery (Natural Gardener) doesn't carry greensand.

I'm not getting bare spots but my lawn is looking "strained". Growing fine (slowing down now with shorter days and colder weather) but just not a uniform color.

Am including 3 pics which should provide a sense of what I'm seeing. I definitely have some general fungus issues but I expect that with the amount of moisture we've had. But since the yellowing started before all the wet weather hit I think I've got something more than "typical" fungus going on.

I'm inclined to apply some chelated iron just to see if the yellowing is simply an iron chlorosis issue. Suggestions welcome.

Does anyone have a suggestion for a chelated iron product to apply to a St. Augustine lawn? There appears to be a lot of different "flavors" of iron amendment products and I'm totally confused as to what I should be looking for. Thanks!

You can try any of the iron supplements...if only to confirm for us that they still don't work to correct the general chlorosis seen in the last picture. Forget for a moment the mottled blades in that picture, the overall color change is the problem I tried to describe. Greensand is the only thing I've tried to fix it. At this point in the year, you could simply wait it out. Next March/April the grass will all be green.

The first picture in this last batch is a mix of rain induced chlorosis and the fungal spots.

Thanks dchall. I guess I'll keep looking for greensand and hope to find a source before spring arrives. My lawn always starts out lush and green in spring, it's just the gradual yellowing throughout the summer and fall that has discouraged me the last two years. I will try an experiment with chelated iron once the yellowing begins again next summer but am not optimistic.

I had to review this topic to see if I had mentioned corn meal as a solution to the brown spots on the grass blades. I have used corn meal successfully since 2002 to repair dead looking st Augustine after letting it seemingly die. In Texas the heat for most of the year makes it not recommended to use chemical fungicides. But corn meal seems to work even in the heat. There are people around the country who try to disclaim the use of corn meal as a fungal cure but they have not tried it. For those of use who have tried it, it seems to work. Having said that I am thinking back to another summer where we had many inches of rain with no sunny days for the early part of the summer. As I recall the corn meal did not fully cure the disease in that season, but I believe it kept the disease from worsening. By repeating the applications the following spring, the disease went away. The application rate is 15 to 20 pounds per 1,000 square feet. Corn meal does not help for the general chlorosis, but it helps for the fungal lesions on the blades.

Preachin' to the choir! Fungus had been our main problem for years, to the point where it was suggested we re-sod large portions of our lawn. Instead, we switched to an organic program including the application of cornmeal regularly. The impact was dramatic and our fungus problems were brought under control. We have had an increase this year in the spotty fungus which appears in my pictures but given the pattern of continual wet weather we've had the last two summers that's to be expected. Unfortunately, cornmeal hasn't seemed to stem the spread of my yellowing problem but I'll keep up the applications (one more this season and then start again in February) as I'm convinced it works well on our other fungal issues.

I am very happy to have a choir to preach to. Glad it is working for you. I wish some of the universities around would give it a shot.