Knowledgebase
Help with identifying lawn fungus #874338
Asked June 23, 2024, 7:57 PM EDT
Hello-
I live in Milliken, Colorado and seeking help diagnosing an issue with my lawn in my front yard. After doing some research online I believe my yard has a fungus known as melting out/leaf spot. I would be grateful if CSU could confirm or help identify the issue, I am experiencing. Attached are pictures before fungicide application and after in addition to a soil test from March 2024. I have additional photos if needed, page wont let me upload more than three. I provided notes below that maybe useful.
Turf Type
766 sq feet blend of Kentucky Blue, Rye and Fescue. - I also have some tall fescue patches .
Lawn History
Purchased home in May of 2022. Grass was in terrible condition. With some general care, frequent cutting, fertilizer and watering routine the grass was in much better condition by September 2022. Spring of 2023 the grass was thriving but by mid-June I began to see a lime green color throughout the lawn. I believed the lime green color to be an iron deficiency so I began introducing iron with my fertilizer applications. The iron helped but only for a short period of time and the color issue still exists to this day in the backyard as well.
Possible Mistake
Mid-March 2024 my grass remained dormant. Little to no signs of life. By mid-April I grew concerned with very little progress coming out of dormancy. The grass looked extremely dehydrated and appeared dormant. With little moisture in March and April I began to water my lawn thinking the lack of moisture was the problem. By mid-May my lawn was greening up but appeared to still have areas that were dormant.
June 1st was when I started to take a deep look since the thought of the grass coming out of dormancy was out of question this late into the season. It was then I noticed yellow blades, spotting, along with dead blades mixed in. Looking back, I believe I made a huge error watering a good amount that early in the season with cooler temperatures.
What I have done as of 6/23
Reduced watering to from 5 days a week to 3 days a week.
June 5th - Dethatched
June 10th- Applied .58oz of Azoxystrobin and 1.58oz of Propiconazole
183411 Azoxy 2SC TO 1G Specimen.indd (cdms.net)
Prime Source Propiconazole 14.3 Select Fungicide – Agroterra (agroterrausa.com)
Fertilizer History
In 2022 and 2023 I was on Scotts fertilizer program(granular). By mid-June 2023 I began incorporating iron as I mentioned in the history. Not satisfied with my lawn in 2023 I began looking into how I could make improvements in 2024.
In early march of 2024, I did a soil test. Based on its results I made the decision to switch from granular fertilizers to a liquid spoon-feeding program (backpack sprayer) so I could be more precise increasing specific nutrients,.
May 12, 2024 was my first fertilizer application. I used a product called GrowORR 17-0-17 by lawn supply company in addition to a micro nutrient supplement. I followed the associated rates for my sq ft.
Weld County Colorado
Expert Response
You've asked a complicated question and given us lots of information. I'm working on your query.
Sue, Weld County Master Gardener
Mr. Paradisa,
You are doing so many things right and I think you’ve diagnosed your own problem pretty well.
I cannot magnify your photos of the leaf blades enough, so I’m checking in with you for a good description of the symptoms. Leaf spot symptoms include small, purple-to-black spots on individual leaf blades. The spots become elliptical in shape and may be surrounded by a purple border. Tissue in the center of the spot may die and turn a beige or straw color. If a spot extends across the leaf, the blades wither and die.
Is that what you are seeing?
How old is your house? Leaf spot is more common on lawns that were seeded or sodded prior to 1980, because the bluegrass varieties used during that time had relatively poor resistance to leaf spot.
Why might this happen? Colorado State University Extension’s research-based bulletin suggests that leaf spot and melting out diseases occur in lawns that are stressed from excessive nitrogen fertilizer, excessive water and a very short mowing height. This seems to be what you suspected, doesn’t it, Mr. Paradisa?
Two additional suggestions: check your irrigation system for uneven coverage and consider mowing your lawn to a longer blade length. Additionally, if you decide to reseed or overseed, please do consider buying a good quality grass seed mix that is suitable for our area.
For general information, refer to https://planttalk.colostate.edu/topics/lawns/1555-spring-weed-management-lawns/
Table one of https://extension.colostate.edu/topic-areas/yard-garden/lawn-care-7-202/ will give you specific suggestions for fertilizer application
For LOTS of very-detailed information about turf care, go to https://cmg.extension.colostate.edu/Gardennotes/551.pdf
(I think you’ll really enjoy this one!)
If you have additional questions or concerns, please do not hesitate to contact CSU Extension again.
Here’s to your healthy, great-looking lawn.
Sue, Weld County Colorado Master Gardener
- Is that what you are seeing?
- Yes, that's what I am seeing. However I do find myself finding characteristics of grey leaf spot but I could be wrong. Which is the primary reason for my email. I'm having a hard time deciphering between the two fungus. Regardless I believe they are both treated in the same manner.
- How old is your house?
- Home was built in 2017. The contractors threw sod or seed down the same year.
