Battling Leaf Spot for 8 Weeks

Kentucky bluegrass, Fescue, Rye and Bent, etc
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hazard209
Posts: 26
Joined: July 8th, 2021, 10:20 pm
Location: Southwestern, PA
Grass Type: KBG, PRG, TTTF Mix
Lawn Size: < 1000
Level: Some Experience

Battling Leaf Spot for 8 Weeks

Post by hazard209 » August 1st, 2021, 2:55 pm

I have been fighting leaf spot in my lawn for several weeks now and am hoping that someone will have a suggestion as to what I can do to finally get rid of this fungus. Below is what I've tried so far:
  • DiseaseX at curative rate on 06/12/2021
  • Second app of DiseaseX at curative rate and a foliar application of propiconazole at the curative rate on 06/27/2021
  • Granular app of propiconazole (bioadvanced fungus control) at the curative rate and Thiophanate (Clearys 336F) foliar application at the curative rate on 07/10/2021
  • Another app of DiseaseX at the curative rate and another app of Thiophanate (Clearys 336F) foliar application at the curative rate on 07/24/2021
I'm seeing dead grass mixed throughout the lawn and I don't want to keep throwing fungicide at it if it's not working. I typically mow at a height of 4" but lowered to 3.5" today. We've had a really wet summer overall but haven't had rain in about a week and it's not supposed to rain this week either. I would typically water in this situation to make sure that the grass doesn't die off, but am now hesitant to do so.

Any thoughts, suggestions, or criticisms are appreciated!


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MorpheusPA
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Location: Zone 6 (Eastern PA)
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Re: Battling Leaf Spot for 8 Weeks

Post by MorpheusPA » August 1st, 2021, 5:35 pm

Some of that MIGHT be just a bit of a disease and I'll let others speak to that, but the brown stuff you see in the grass is called BBDL. Other than BBDL, I see nothing indicative of anything severe.

Brown Blades Down Low. :-) It's normal. Grass sloughs off old, dying blades and throws them away, where they drop off and rot, adding their mass back into the soil and releasing their resources back into the mass as well.

Then, I'd clean, disinfect, and check your blade tips on your mower. Just wipe them with a wet rag that has at least 10% bleach added to it (wear crappy clothes for this). If the blades are dull, sharpen them, or have them sharpened. If bad, replace. Nobody ever thinks of your blade as a disease vector, but it is--as is the entire deck of your mower. Clean everything, remove caked-on grass, and disinfect it (10% bleach mix will do that pretty well).

hazard209
Posts: 26
Joined: July 8th, 2021, 10:20 pm
Location: Southwestern, PA
Grass Type: KBG, PRG, TTTF Mix
Lawn Size: < 1000
Level: Some Experience

Re: Battling Leaf Spot for 8 Weeks

Post by hazard209 » August 1st, 2021, 7:00 pm

MorpheusPA wrote:
August 1st, 2021, 5:35 pm
Some of that MIGHT be just a bit of a disease and I'll let others speak to that, but the brown stuff you see in the grass is called BBDL. Other than BBDL, I see nothing indicative of anything severe.

Brown Blades Down Low. :-) It's normal. Grass sloughs off old, dying blades and throws them away, where they drop off and rot, adding their mass back into the soil and releasing their resources back into the mass as well.

Then, I'd clean, disinfect, and check your blade tips on your mower. Just wipe them with a wet rag that has at least 10% bleach added to it (wear crappy clothes for this). If the blades are dull, sharpen them, or have them sharpened. If bad, replace. Nobody ever thinks of your blade as a disease vector, but it is--as is the entire deck of your mower. Clean everything, remove caked-on grass, and disinfect it (10% bleach mix will do that pretty well).
Thanks for the reply MorpheusPA! When this started, I did replace my blades and cleaned off all of the caked on grass from the deck. I'll clean everything off again and hit it with the bleach solution. Maybe sharpen the blades while I'm at it. I've been bagging all of my clippings out of concern. What had me worried most that this was disease was the sheer amount of rain we've had and the amount of brown throughout the lawn. Especially after not having this issue earlier on in the season (May) and all of the sudden in June it seemed to rear its head.

BBDL is a possibility, but I haven't noticed this sort of die off in my lawn before. I've done two fall overseeds the past two years as the yard was weed ridden in 2019 previously. There wasn't enough grass to really see this type of activity before that.

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MorpheusPA
Posts: 18129
Joined: March 5th, 2009, 7:32 pm
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Re: Battling Leaf Spot for 8 Weeks

Post by MorpheusPA » August 1st, 2021, 9:14 pm

To my eye, it actually doesn't look that bad. A little sickly, maybe, but not awful.

I'd suggest, for future overseeds, choosing different grass species that don't suffer those losses.

For the plucked blade, I'm going to guess you went looking for a bad blade. Not that we usually have to look very far (1 blade in 20 or so should actually look pretty bad at any one time just due to normal regeneration). If there is a disease there, it's under control.

hazard209
Posts: 26
Joined: July 8th, 2021, 10:20 pm
Location: Southwestern, PA
Grass Type: KBG, PRG, TTTF Mix
Lawn Size: < 1000
Level: Some Experience

Re: Battling Leaf Spot for 8 Weeks

Post by hazard209 » August 4th, 2021, 7:31 pm

I did go looking for that blade just as an example of what kind of spots I was seeing in the lawn. I'll let it go at this point and see if gets much worse. I definitely went with the shotgun approach on cultivars since I didn't know what was specifically in the lawn originally and, in hindsight, I wish I had just killed it all off to start fresh.

Here's what I've seeded with from SSS for reference:

SS9000 Perennial Rye Blend
Slugger 3GL
Grand Slam GLD
Stellar 3GL

SS1000 Tall Fescue blend
Amity
4th millennium srp
Avenger II
Raptor 3

SS1100 Bluegrass Blend
Bluebank
Midnight
Mazma

Fahrenheit 90 KBG
Bandera KBG
Blue Note KBG
Beyond KBG


hazard209
Posts: 26
Joined: July 8th, 2021, 10:20 pm
Location: Southwestern, PA
Grass Type: KBG, PRG, TTTF Mix
Lawn Size: < 1000
Level: Some Experience

Re: Battling Leaf Spot for 8 Weeks

Post by hazard209 » May 17th, 2022, 8:25 pm

Just an update to this, unfortunately I seem to be having the same problem again this spring. I put DiseaseEx down on 05/13 and it was watered in on 05/15 with the rain. I cleaned my mower deck and blades with the bleach solution as well as sharpened the blades before the first mow. The bigger concern for me is that this is happening in spring when the lawn really shouldn't be stressed like it was last summer.

Going to keep an eye on it but hope that it stays controlled with the fungicide application.


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MorpheusPA
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Re: Battling Leaf Spot for 8 Weeks

Post by MorpheusPA » May 18th, 2022, 12:41 pm

Now it's a bit more indicative of a disease, but it's not really standing out as to which one. But something's not right, although it's not extremely wrong, either. We've done your soil test, yes?

One thing I do notice is that there seems to be an enormous amount of density there, so I'm thinking the grass is trying to thin out a bit at spring's end.

hazard209
Posts: 26
Joined: July 8th, 2021, 10:20 pm
Location: Southwestern, PA
Grass Type: KBG, PRG, TTTF Mix
Lawn Size: < 1000
Level: Some Experience

Re: Battling Leaf Spot for 8 Weeks

Post by hazard209 » May 18th, 2022, 3:26 pm

Yessir we did do the soil test. Overall it was good, a little low in iron and high in calcium & sulfur (naturally high in gypsum?). pH is a little high at 7. Test is here: viewtopic.php?f=11&t=27061

Applications so far:
  • 4/10 - Prodiamine
  • 05/13 - DiseaseEx at 3lbs/1000

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