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cgoll 06-01-2010 08:51 PM

Dark green spots on lawn
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I've been putting a lot of work into my lawn the last couple years and it is looking the best ever. Not perfect, but a lot better than it has been.

I'm getting these dark green spots. Any idea what they are? They are in the back yard that is shady in the am but full sun in the pm. They are about 3-5 inches in diameter but some larger areas. That is a weeder handle you see in the second picture.

No pets (outdoors at least).

At first I thought bird droppings because I first noticed them by a tree line, but now I see them out in the middle of the lawn.

When I fertilize I always do it twice with perpendicular passes with a broadcast spreader.

Any thoughts?

gmhammes 06-01-2010 09:47 PM

sorry, should have read further... still thinking.

reggieh 06-01-2010 10:52 PM

I would say that you are over fertilizing the lawn. You should always broadcast lateral towards the house. I can see streaks in the lawn also.

gmhammes 06-02-2010 09:21 AM

it is quite possible that your lawn is getting burned out (so to speak), couple good rains and fair weather should bring it back.

cgoll 06-02-2010 02:37 PM

No, not burned out. Have a sprinkler system. In fact, those areas have significant coverage (heads from 3 zones hit those areas).

Which supports the theory of a friend from work: Fungus!

So, I will apply a fungicide and turn those zone run times way down and report back later.

However, my ears are still open to any other thoughts.

downunder 06-02-2010 05:10 PM

Don't think I can address NJ diseases from GA. However, in my opinion as a Master Gardener and Ga Certified Landscape Professional I think you are OK in your fertilizing procedure and irrigation plans. Don't know what the process of going "lateral towards the house" is. The only overfertilizing signs I have seen are burning, which you don't have and occasionally the extra new growth encouraging some southern diseases but I will stay out of that since it is not appropriate here and will only add confusion. And having to mow more often:thumbup:!

Could you tell us what your lawn is please?

downunder 06-02-2010 05:47 PM

Sorry, I had to go away for a few minutes. Could you please tell us what you have done, and when, so far this spring.

Some of the lawn looks a little thin and the color could be better. As far as the spots in the original concern, it could be pet urine but it seems to me that's a lot of spots for that problem. I would be inclined to aerate, fertilize, irrigate well one time early in the morning, then turn the irrigation off for about a week. Most fungi prefer the moisture and will diminish if the lawn dries out. The idea here is to water the grass plant well into the root zone below the fungus, then let the top of the soil dry out without stressing the grass. If pets are a problem, a good irrigation should help dilute the urine from the grass.

To clarify, or possibly digress- If in doubt with any plant as far as drought stress or stress from overwatering, I always water well then allow it to dry out. Overwatering causes rot, fungi, etc but it takes a longer period of time. If the plant is overwatered and you water it one more time, you will not break the bank. One time extra will not push the plant over the wall unless it is about gone anyway. Drought stress comes on much more quickly and those plants respond very quickly to the irrigation. Note- a good irrigation is not the same as a sprinkling. The point as it relates to this thread is that you shouldn't hurt with an extra light fertilization and one good irrigation. If the lawn doesn't immediately respond (within 48 hours) you can rule out that it was nutrient or drought. It must dry out first to impact any fungi so don't do this if the weather is not favorable.

cgoll 06-02-2010 09:10 PM

Downunder, thanks for the interest.

What is my lawn? My lawn is a mutt. It has some of every thing (blue grass, fescue, perennial rye, and unfortunately some orchard grass that is a bright emerald color and grows twice as fast as everything else).

So far this year I have fertilized twice; once w/ Scotts w/ Halts in April when the forsythia were blooming and again in early May w/ a no-name brand. Both times were about 50% greater than the specified application rate.

Sprinkler system is timed to start at about 3 am and goes 4 days a week. 12 zones, each zone for about 13 minutes each this time of year. (July and August run 20% longer.) That way it ends before I need to get in the shower.

So, it is well fed and well watered IMHO. And yes it grows fast. Gets cut twice a week; once by landscaper and once by me, with my cutting height the highest my tractor will go.

This evening I turned off the sprinkler zones in the affected areas and sprayed a fungicide.

We'll see what it does....

boman47k 06-03-2010 07:37 AM


highest my tractor will go
Why cut so high? Does that not encourage more thatch?


Both times were about 50% greater than the specified application rate
Why? More is better?

It will be interesting to see what the solution turns out to be.

Just seems like a lot of fertilizer and water. Maybe it never has time to dry out, especially with the grass being so tall.

downunder 06-03-2010 04:57 PM


Sprinkler system is timed to start at about 3 am and goes 4 days a week. 12 zones, each zone for about 13 minutes each this time of year.
There's your problem. Way too often- keeping the top wet but not getting to the roots. Well, that's not quite accurate. Your are encouraging very shallow roots with the frequent light watering so they are getting the water. Once a week with at least an inch of water that soaks down into at least six inches of soil is much better.


That way it ends before I need to get in the shower.
This is the other problem. Set it to come about 1:00 am and run at least 30 minutes each zone. I presume that you don't need to get up real early in Saturdays.

boman47k makes a couple of good points.
The second fertilization was not a good idea.
Mowing high and frequent watering does not let the grass dry out and this causes fungus problems just like keeping feet wet causes athlete's foot/ trenchfoot. EEWWWHHHH! I can hear your mutt howling all the way down here in Georgia!
However, cutting high does not cause thatch. IMO thatch is blamed for way too many problems. If thatch, which is a buildup of roots and dead grass at the soil level, gets to the point that it prevents air and water from getting to the lawn's roots, then it is a problem.
Also, cutting high is recognized as having several benefits for most lawns, except bermuda, etc. so no problem there. I'll just leave it at that.

boman47k 06-03-2010 07:32 PM

Just curious, are the green areas in dips/depressions in the lawn?

cgoll 06-03-2010 10:00 PM

Thanks for the insights. I think you are right that it is a watering issue. The problem is limited to the shadiest area of the lawn (less than 15% of the total turf area); all the rest of the lawn is unaffected.

But the green spots are not depressions; the singular ones are about the size of a fist or less and I do not recall any variations in those areas. There is a valley in the front yard that gets fertilizer run-off/accumulation and it is greener than the higher areas but I don't think that is what's happening in the back yard.

I've turned off the sprinkler zones in the back. Unfortunately it rained tonight and there is a 30% or greater chance of rain every day for the next 3 days so I don't know how dry it will get back there any time soon.

The fungicide I applied yesterday is doing something. There were some small mushrooms in the back but strangely they are not directly in the affected areas. They are looking very sick as of this evening.

I will take your advice, Downunder, and switch to a once weekly, but longer duration watering schedule. Guess I'll have to do some investigating to see how long it takes my system to put down an inch of water. (i.e. pans placed in various spots for a set amount of time and then do the math...)

Any ideas how long it would take for the fungicide to show results? I guess that would probably depend on if the rains stop and let it dry out.

chrisn 06-04-2010 04:12 AM

Just curious also but are you only supposed to fertilize every 3 months?:huh:

downunder 06-04-2010 02:13 PM


Guess I'll have to do some investigating to see how long it takes my system to put down an inch of water. (i.e. pans placed in various spots for a set amount of time and then do the math...)
This is exactly how most people get a measurement. There is an old adage of taking tuna cans, cat food cans, etc which are about an inch deep and placing them around the area and get a good average.

Fungicides should show results in a couple of days. It needs to be watered in so the rain should help there, unless you get one of those wierd floods the country has had but hopefully not that much.

BTW- Mushrooms are fungi.

boman47k 06-04-2010 08:20 PM

I was going to ask how you know what size pans to use. The averaging makes sense I guess.

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