Lawn starting to yellow

Discussion in 'Pesticide & Herbicide Application' started by mac43rn, May 26, 2002.

  1. mac43rn

    mac43rn LawnSite Member
    Messages: 238

    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?
  2. KirbysLawn

    KirbysLawn Millenium Member
    Messages: 3,485

    What kind of grass? How sharp is the blade? Look like this?

    grass 2.jpg
  3. mac43rn

    mac43rn LawnSite Member
    Messages: 238

    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

  4. ohiolawnguy

    ohiolawnguy LawnSite Senior Member
    Messages: 397

    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.
  5. lawnstudent

    lawnstudent LawnSite Senior Member
    Messages: 472

    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.


    MATTHEW LawnSite Senior Member
    from NE OHIO
    Messages: 665

    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.
  7. mac43rn

    mac43rn LawnSite Member
    Messages: 238

    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.

  8. Runner

    Runner LawnSite Fanatic
    Messages: 13,497

    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.;)
  9. tremor

    tremor LawnSite Bronze Member
    Messages: 1,476


    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.

  10. mac43rn

    mac43rn LawnSite Member
    Messages: 238

    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


Share This Page