View Full Version : Lawn starting to yellow

05-26-2002, 11:07 AM
I have a new lawn as of sept of 2001. The lawn came up really nice. The first two applications were actually the same 12-4-8 with some sort of pre-m (First app went down on April 2 and second app on May 21. For the record we have had a ton of rain. 22.75 inches since March 1. Now all of the sudden the grass is turning yellow, especially at the tips. What are your guys opinions on this and also the applications being applied. I don't think it is a fungus because it really has not been all that warm (not ideal conditions). It almost looks to me like the lawn is starving, either nitrogen or iron deficient. This same company use to take care of my first house. I use to have to mow the lawn every 4-5 days. Now I go 10 days before mowing. This is what leads me to believe the lawn is lacking nitrogen.

any suggestions?

05-26-2002, 11:49 AM
What kind of grass? How sharp is the blade? Look like this?

05-26-2002, 12:12 PM
no not really, it is a more distinct yellow. I have pics, but to get them to post here, I have to reduce the size so much the picture is too small. any help on pics and I will post of pic of the blades.


The grass is a three way blend tall fesuce with 10% ky blue


05-26-2002, 04:48 PM
we have a lawn which we installed in 1997. sod not seed. the lawn has irrigation(not being used yet this year), and whenever we have a lot of rain, the lawns tends to yellow out, and not grow very much. as soon as the rain subsides, and the sun comes out for a week, the lawn greens up again. at first i thought the same things as you(IRON) when i first noticed the problem at this lawn. but, just like some sort of magic, as soon as the lawn dries up some, POOf no more yellow grass. I honestly can't explain it.

if it is raining enough during the year, i ask the customer not to use the irrigation.

BTW, the lawn i am referring to is very yellowed out right now. mowed once a week, but could go ten days if i wanted to.

05-26-2002, 05:58 PM
The Pre-emergence lables that I have I read all indicate that they should not be applied in spring to a lawn that was established last fall. Maybe someone like Tremor or Kirby'slawn who has more expeirence than I could comment here.

A yellowing leaf could indicate a chlorosis - iron deficiency. It could also be that you've pruned your young lawn's roots with the Pre-emergence. Good luck.


05-26-2002, 06:15 PM
The pre-m certainly weakened the plant and should not have been applied. There is a good possibility that the problem is leaf spot (helminthosporium). It thrives in cool, wet weather. It begins with tiny black spots on the leaf tissue and progresses into large yellow spots eventually covering the plant. The final stage is the melt-out stage where it dies off in patches. Most lawns only get melt out in spots. Pick up a few blades and look for the spots. If it is there, a fungicide will stop the spread for a few weeks. Nitrogen tends to accelerate the spread. You can also spread it from lawn to lawn (or re-spread it week to week on the same lawn) by having spores on the mower wheels and blades. They should be sprayed off after each cut, if possible.
If it is iron chlorosis, an application of iron will do the trick. Good luck.

05-26-2002, 07:46 PM
I have pics and would love to post. Any way I could send them to an administrator and have them post. I know how to post, but the files are too large. Any help would be greatly appreciated.


05-26-2002, 09:03 PM
Some yellowing is normal for this time of year for our region. The grass is stressing right now, as it is reproducing. (seeding). Much of what you're seeing right now is because of the amount of stem material that is exposed. Later in the season, after we're cutting more leaf, it won't show so bad. Hit it with Lesco 24-5-11 w/ Iron, and hang on to your mowing rear, because this stuff is going to come in so thick, you won't believe it. You'll like it, but won't believe it.;)

05-26-2002, 09:15 PM

The Pre-M would be OK if the lawn has been cut at least twice prior to treatment. It sounds like that is the case.

Have you had a soil test done? There may be a micronutrient deficiency, or I think more likely, a poor cation exchange capacity (CEC on the test).
Even the Ph could be way out of wack so we need to start there.

Let's also think about that fert with Pre-M a minute here. The fertilizer analysis was 12-4-8. A fair ratio, yet very low in analysis. If the Pendimethalin content was the ever popular .86%, then the product would have been applied at about 4lbs/M. So we got a whopping .48lbs of N applied twice to a new lawn since spring began. Just in case that isn't bad enough, we've also gotten over 22" of rain.

I'd hit that puppy with a minimum of .75lbs/N (or more) from at least a 50% or 75% slow release N material. With or without the soil tests results back from the lab I'd fert it now. But do the soil test too.


05-26-2002, 11:31 PM
The lawn had been cut three times before they put down the pre-m.

I had a soil test done on April 15, 2002.

pH - 6.6

P- 20 ppm (medium)
K - 66 ppm (low)
Ca - 1328 (medium)
Mg - 223 ppm (very high)

Calculated Cation Exchange 7.6 meq/100g

Calculated Cation Saturation

%K 2.1
%Ca 69
%Mg 22.5
% H 6.0

K:Mg Ratio 0.09

any suggestions


05-27-2002, 01:09 AM
Next two posts are images sent to me by mac43rn.

One pic from mac43rn:

05-27-2002, 01:22 AM
Low web graphics doesn't show reddish spots on bottom 2 green leaves. Do you get an orange dust on your shoes when mowing or walking a lot in the lawn? If so, most likely is rust, unusual early in year, but possible in the weather we've had this year. Take a look at <a href="http://www.agcom.purdue.edu/AgCom/Pubs/BP/BP-110-W.pdf">Leaf Rust</a>.

A little closer look:

05-27-2002, 07:40 AM
I don't see the lessions usually associated with a leafspot. I also don't see the rust spores on those leaves. A severe Nitrogen deficiency would produce yellowing from the top of the blade progressing downward, but stunting of the grass is associated with this problem. Does the grass look stunted? I don't see stunting in the picture, but I also don't have a reference in the picture. Have you looked at the roots? Do you have roots? Do you see signs of root rot? What color are the roots? Are they black? Healthy roots should be light in color. Is this problem everywhere at once on the site or is it appearing in patches?


05-27-2002, 08:23 AM
How about nematodes? A possibility?

05-28-2002, 09:04 AM
I don't know what stunted looks like, but I will tell you I am only mowing my lawn every 10 days. Seems awful stunted to me with this kind of weather.

05-29-2002, 05:41 AM
Hey Mac,
Rain, Rain, go away. But come back another day.
Have seen the same thing here old KY. Too much rain this spring.
You will see this in Fescue type sods. It is stress of too much rain then turning off hot and dry.

A little starter fert. and watering will help. I don't have to tell you mow your grass high.
Iron will give you a quick fix on the greenup. Will not last long.

Looks like there is starts of Brown patch. Nothing really you can do about this fungus. Just don't water in the evening late. If you do water early enough that it dries before night fall.

05-30-2002, 07:01 AM

That soil test result is OK except for the fairly low CEC & Potash. Your best bet would be to rely on slow release fertilizers during the "grow-in" (& beyond) to prevent the applied elements from becoming a part of the soil solution all at once. Low CEC soils won't "give nutrients back" to plants very easily. So slow release sources will improve fate & efficiency of those elements.

Iron will improve the color of the existing leaf canopy. But it won't do much to "build" that canopy. Nitrogen (N) is the element your young lawn needs right now.

Tall Fescue will take at least a year to build the burly root system that makes it such a desirable lawn. With the pathetic little root system it has right now, your lawn can't find all the N it needs. That will improve as the next year goes on.

I'll assume that my previous calculation was correct & that the lawn has only had 1lb of perhaps a 30% slow release N since this year started. There doesn't appear to be any diseases working in the photos that posted. The dead leaves were sacrificed to sustain the younger ones needs. To confirm this theory, pull out a single plant. If only the lowest (oldest & futhest from the center of the sheath) leaves are turning brown & the 2 or 3 newest ones (closest to the center of the sheath) are green or fading to brown, then N is the culprit. You would also check for signs of insect activity but the presence of insects wouldn't negate the need for N.

See if you can pick up a product like our 21-3-21 75% PPSCU (LESCO SKU 000998) or similar higher potash blend (it's low on test). Apply at 1lb N/K. You "could" see a little Brown Patch on Tall Fescue when it's being grown in at higher fertility levels. But that would be the lesser of 2 evils right now.
Aim for at least 3.5-4lbs/N for the balance of this year then scale things back a little for 2003. Tall Fescue doesn't require much N (maybe 2.5-3.5lbs per season) after it's established. But for now, it does. I'd apply 4.5-5lbs/N this year with most of that after Labor day. example 1lbN allready, 1lb/N NOW, .75lb/N in 6-8 weeks, 1lbN at Labor Day, 1.25lbs N 7 weeks later.

Over time, you can improve CEC by gradually building up organic matter in the soil. This is accomplished by returning clippings, natural root slough, top dressing lightly with compost/manure/what have you, and through the use of natural organic fertilizers when seasonally appropriate. The NatOrg. ferts are too slow to assist you (much) in the grow in process, but should play a role in the future maintenace program.

A friend had the same problem that you do now. We worked his soil by aerating twice a year then topdressing with composted peat & manure then dragging it in. This was done twice a year every year for 4 years. That lawn was incredible & the CEC was improved after the 3rd year. We still practiced a good 4 app. program. He has since sold that house, but even with minimal effort, the new owners have the best lawn on their block.

Let us know how this works out.


Lawn Man 5
05-30-2002, 12:59 PM
Originally posted by KirbysLawn
What kind of grass? How sharp is the blade? Look like this?

Kirbys Lawn:

Some of my grass Is like the one piece on the left. (brown in the middle and kind of round) But others in the yard are nice and wide real green. I live in north eastern Ohio. and the grass is kentucky Blue and perinal rye grass. We have had quite a bit of rain so far. My blades are sharp. I just wondered why some was yellow and some was real nice. What could i possibly do about this problem.