PH and Possible Fungus #747999 - Ask Extension

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PH and Possible Fungus #747999

Asked May 04, 2021, 3:47 PM EDT

Hello and thank you for taking the time to answer my questions. I recently noticed that my lawn has some yellow, brown and black spots on some of leaves (pic 1). Understand the weather has been up and down this might just be some winter die off. Is this a fungus and if so what type and what do you recommend? Also, recently had a soil test and my PH is 7.13 ( pic 2 and pic 3). Is this considered too high for cool season turf? If so, what suggestions do you have to lower the PH and what is the ideal PH. I am concerned that several some of my nutrients might be locked up. Thank you for your time

Macomb County Michigan

Expert Response

In regards to the spots, are you seeing any larger areas or patches where the turf is yellowing, browning or otherwise unhealthy looking? If so, could you include pictures of the patches? The best defense against the more common lawn diseases in Michigan is a healthy turf. This publication outlines some good general principles for maintaining a healthy stand of turf. http://plantpathology.ca.uky.edu/files/ppfs-or-t-11.pdf

Adjusting the pH of soil, especially over a large area like a lawn, can be a challenge. Soils have a high buffering capacity and generally need ongoing applications. A pH of 7.1 wouldn't be something we would normally recommend adjusting for cool-season turf. https://turf.purdue.edu/changing-soil-ph-under-turf/
Lori Imboden Replied May 04, 2021, 5:56 PM EDT
Good Morning,

Thank you for the quick reply. There are several areas that I see what might possibly Melting out. They are not large area but they are approximately 6-8 inches in circumference. 

Turf is a mixture of TTF, KBG and Rye. HOC is 3.25 until summer when I go to 3.5 or 4.0. I have done two fertilizer applications and one app of Prodiamine @ 3lbs/1,000. I have not applied any fungicides at this time.  I try to maintain a healthy lawn and I dethatched last spring and fall. 

Here are some additional pics  I have about 10 spots like this in the middle of my yard  imageimageimageimageimage
imageimage
Sent from my iPhone

On May 4, 2021, at 5:58 PM, Ask Extension <askextension@eduworks.com> wrote:


Jennifer Hamm Replied May 05, 2021, 7:32 AM EDT

Our turf disease specialist does agree that this looks like symptoms of melting out. The fungicide azoxystrobin is registered for control of melting out on residential lawns. They also indicate that daily irrigation of 1/10 of an inch of water from an irrigation system will prevent the disease from becoming a problem. Other cultural controls that can prevent the spread are summarized in this post from OSU (https://u.osu.edu/athleticfieldmanagement/2017/04/03/leaf-spotmelting-out/):

  • Mow the turf high (2.5 – 3 inches) to provide leaves that produce food for the plant and maintain a healthier lawn.
  • Avoid excessive nitrogen fertilization in spring which promotes lush growth. The use of fall and late fall fertilization is recommended. Once in the melting out phase maintain the lawn with a complete fertilizer at modest rate to encourage healthy turf and recovery. Often a starter fertilizer is recommended.
  • Do not over water the turf if the lawn is irrigated.
  • Manage thatch by frequent and heavy core cultivation (aeration) of the lawn. This will also promote a deeper healthier deeper root system.
  • Plant resistant cultivars of Kentucky bluegrass. For information on these refer to the National Turfgrass Evaluation Program
  • Fungicides can be applied but for best results need to be made early in the disease cycle or as a preventative treatment. This is done based on a history of the disease in the lawn. Unfortunately the most effective fungicides are no longer registered for use on residential lawns.




Lori Imboden Replied May 06, 2021, 11:19 AM EDT

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