Start with diminishing daylight, cooler night time temps . . . plant uptake has slowed considerably.

There are a LOT of factors involved right now, but I won't comment further, since I'm in an area where the lawns actually do go dormant for 75-90 days.

There was an interesting thread from several years back about keeping lawns green as long possible. Do a search.

 

Thanks for answering your reasons make a lot of scense. The only thing is it seems to happen more on my lawns...you can see the discoloration stop right at the property line. It has to be something I'm doing differant than everyone else.

 

Look at the blades closely in the yellow areas. I was asked to look at a lawn yesterday under TG's care. The green areas were very green but there were large patches of flourescent yellow. On closer inspection, everywhere the blades were yellow I found gray leaf spot. The excess nitrogen that they apply could be feeding the disease. Also the damp overcast skies we have had over the last week will make it worse.
As the skies clear and the weather cools it should start to go away on its own.
We have never found a need to treat for gray leaf spot.
Here is some good information as well.
http://edis.ifas.ufl.edu/PP126

 

i don't know about that lawn and the grey leafspot, but i have several companies ask me about the same thing . bright yellow spots our first thoughts were too much water/ lack of iron this proved false after continued monitoring and increasing companies asking the same questions.
then some one came up with nitrogen induce chlorosis.
now some one i have known for a long time and have great respect for their knowledge told me something and my first thought was no way.
all i will say here now is use a fungicide that is labeled for brown patch and try it on a lawn to see results. that's where we are at right now

 

My thoughts are too much nitrogen or an iron deficiency if its not disease. An insight into your fertilizer schedule would help tremendously.

 

My schedule is pretty simple...I fertilize about every 2 months in the summer or whenever my lawns show the need. In the winter don't fertilize at all unless a lawn needs it. The last time I fertilized was about a month to a month 1/2 ago and the discoloration started about 2 weeks after that. It happens to me every year around this time. There is no problem in the summer when I fertilize.

 

Mine is the same this year, I thought iron deficiency and put it down all to no avail.

I am going to look into the post a couple up from mine about using the fungicide.

(Flor-tam St.Augustine in my yard)

 

I am with Greg on this one we see it all the time shortly after fert in cooler weather. Give it a couple of extra weeks it will blend. We use Lesco 20-0-20 slow release this time of year we allways see it.

 

I am with Greg on this one we see it all the time shortly after fert in cooler weather. Give it a couple of extra weeks it will blend. We use Lesco 20-0-20 slow release this time of year we always see it.

Green spots or streaks? Streaks-be looking for a fungus. Patches- low FE. Quick release products are gone, leached out with all our rain as of late. Glad to see you using a quality slow release product. Not instant results but works well. It's akin to eating a huge buffet at a single sitting vs. eating the same meal over a week. You'll be able to assimilate more nutrients over the week vs the over load (single sitting buffet) at one time. Most gets wasted. Same principle with fertilizing turf.

With ferts, you get what you pay for. Maybe a 15-0-15 NPK might be a slightly better choice. A little less N at this time of year but the extra potassium offsets that. Do you recall what micros and % fe was in the 20-0-20?

 

TOTAL NITROGEN (N) ............................................................................. 20.00%
20.00% Urea Nitrogen (N)*
SOLUBLE POTASH (K2O)......................................................................... 20.00%
SULFUR (S) Total........................................................................................ 1.54%
1.54% Free Sulfur (S)
IRON (Fe) Total............................................................................................ 6.00%
0.06% Water Soluble Iron (Fe)
DERIVED FROM: Polymer Coated Sulfur Coated Urea, Urea, Muriate of Potash,
Iron Sucrate.
CHLORINE (Cl) Max. ................................................................................. 15.00%
*3.00% Slowly available Urea Nitrogen from Polymer Coated Sulfur Coated Urea

 

Same things happen to us in the spring--lime to yellow. This was due to too much Nitrogen. It happened where the spreader overlapped but mostly because of the timing of the application In our case during a transition from dormancy to greenup. This could be the same but in your case from too much fertilizer too close to transition from greenup to dormancy. An application of FE will help. Keep us informed.

 

Thanks to everyone for there advice please keep it coming....RAlmaroad what do you mean by application of FE...what is FE?

 

The cumulative effect nitrogen has on the ph of the soil would be my first consideration, more so if you don't believe in lime.
Calcium carbonate and magnesium, that is.

Every time fertilizer is put down, it affects the ph.
This does not usually recover on its own, fertilizer to me is like a drug, we throw it down mostly for effect.
But after the effect wears off the lawn likes to act like it's hung over, that would likely be due to lowered ph levels.
If the ph imbalance is not tended to, subsequent fertilizer treatments give less and less results, while the ph level goes further down, and down, and down.

Without some sort of counter acting agent, the process of simply fertilizing a lawn is, in the long run, usually pretty detrimental.

You can try Iron, afaik it's a separate product not contained in most fertilizers, it's chemical sign or name is Fe (Ferrum), but I'm not sure what effect this has on ph, if any.

 

Thanks to everyone for there advice please keep it coming....RAlmaroad what do you mean by application of FE...what is FE?

Fromthe periodic table Fe is Iron.

 

The affect of pH in the soil is a factor and relates to the ability for the given plant material to uptake or assimilate the nutrients that may be present.

If the pH is too high or too low the plant can't use what may be put down and it's just wasted /washed away with the rain. For example, What's the ideal pH range for this type of grass? What is the soil pH of where it's going?
Are they compatible?

When the pH is too far in either direction (acidic or alkaline) the chemicals or (fertilizer in this case) that are present in the soil for that particular plant but since the pH is out of range (too low or high), the plant can't use them. Different plants have different pH ranges that they do best in. Soil make up(composition and buffering ability) determines how long either a lime or sulfer application will last or how difficult it is to change the soil pH in the long term.

Here in Central FL, the soil is so well buffered with low organic material the pH bounces right back. A bouncing back and forth in itself causes plant stress also. It's best to work with plant material that is suited for your soil's native pH.