New Sod Wiped out by Fungus

Kentucky bluegrass, Fescue, Rye and Bent, etc
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vetrano
Posts: 2
Joined: June 9th, 2020, 4:28 pm
Location: Toronto, Ontario
Grass Type: Kentucky Bluegrass
Lawn Size: < 1000
Level: Some Experience

New Sod Wiped out by Fungus

Post by vetrano » June 12th, 2020, 3:12 pm

Hi everyone, great forum here.

I installed new Kentucky bluegrass sod on May 13 which thinned out at least 50% due to a fungus (I think it was leaf spot and melting out). I’m pretty sure it was because of too much water. I am looking for advice on how to prevent further damage and how to restore the thickness of the lawn.

I am trying to let the soil dry out, but the shade and rain doesn’t help. Earlier this week I raked it lightly but had to be very gentle since the soil was still wet. I am thinking of raking again to remove more of the dead grass/thatch when/if the soil surface dries out.

I am debating if I should seed and/or fertilize now. I have some Scotts starter fertilizer (24-24-4) and some quick release 30-5-5 and can purchase something else if more appropriate. I have been unsuccessful in finding pure Kentucky bluegrass seed. Given the shade and the fact that I have kids who will play on the lawn (running, soccer, etc.) should I stick with pure Kentucky bluegrass if I seed?

Can the remaining Kentucky bluegrass can spread with aggressive fertilizing to fill in the bare spots if I don’t add seeds? I wouldn’t mind picking up a few rolls of sod to replace the worst areas if this strategy will work.

I was also thinking of letting the remaining grass grow long (5" or 6") before mowing again to allow it to recover before additional stress. Is this a good idea?

I am open to suggestions.

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Here is a history of the lawn:
  • South facing backyard with 2 maple trees that provide shade for most of the day.
  • Kentucky bluegrass sod was installed on May 13.
  • Watered daily for the first 7 days
  • Watered every other day from day 8 to about 10 or 12 when the grass was starting to lose a little rigour. I stopped watering as I realized I was adding too much water. The lawn improved within a couple days.
  • I mowed at the highest setting around day 14 or 15 and it was looking really good.
  • I noticed that black spots at approximately day 20 which I believe was leaf spot.
  • Heavy rain at approximately days 20-23 to the point that the lawn was spongy to walk on.
  • Lawn went downhill from here. Lots of those black spots on the grass and over the next week grass blades started going yellow and dying which I think was melting out.

JHazzardB
Posts: 417
Joined: August 7th, 2012, 11:16 am
Location: OKC, OK
Grass Type: Front Yard: KBG blend. Back Bewitched/Nuglade
Lawn Size: 5000-10000
Level: Experienced

Re: New Sod Wiped out by Fungus

Post by JHazzardB » June 13th, 2020, 7:00 pm

Hey vetrano!

What are the temps up in Ontario right now?

Have you used any fungicide to stop the black spots?

To me, it almost looks like the sod had two or three varieties and one of them survived. But honestly, if I had that density of MY bare spots heading into fall, I would be hesitant to overseed and just push fertilizer for fill in. I think with the density it’s at, it will fill in come fall (whenever that is up north).

I don’t remember how hot northern summers get so my experience is taken with a grain of sand. I’d push mild fertilizer weekly or biweekly though. And I’d get a fungicide pronto. What height (in.) were you mowing at the highest setting? I’d say with your raininess and temps, 3-3.25” would be a good HOC to help dry it out and not harbor any more disease.

vetrano
Posts: 2
Joined: June 9th, 2020, 4:28 pm
Location: Toronto, Ontario
Grass Type: Kentucky Bluegrass
Lawn Size: < 1000
Level: Some Experience

Re: New Sod Wiped out by Fungus

Post by vetrano » June 13th, 2020, 9:26 pm

Thanks for the input JHazzardB!
JHazzardB wrote:
June 13th, 2020, 7:00 pm
What are the temps up in Ontario right now?
Highs over the last month ranged from the 60s to 90 with night time lows going down as low as the high 40s.

Next week should be sunny with the highs increasing from 66F tomorrow to the high 80s by next weekend. The following week is supposed to be cooler with highs in the high 70s. Lows will be low to mid 60s throughout.
JHazzardB wrote:
June 13th, 2020, 7:00 pm
Have you used any fungicide to stop the black spots?
Unfortunately our government banned fungicides and herbicides so I don't have access to any.
JHazzardB wrote:
June 13th, 2020, 7:00 pm
To me, it almost looks like the sod had two or three varieties and one of them survived.
I said the exact same thing to my wife a few days ago as the sod farm said they use four varieties. This is part of the reason I am wondering if adding seed to reintroduce other varieties would be a good idea.
JHazzardB wrote:
June 13th, 2020, 7:00 pm
I’d push mild fertilizer weekly or biweekly though.
Would you start fertilizing now or at the end of summer? I was thinking of applying Scotts starter fertilizer that I have on hand (24-24-4) now at their suggested rate. I wasn't sure if applying anything during the summer would be a good idea? Maybe an organic fertilizer?
JHazzardB wrote:
June 13th, 2020, 7:00 pm
What height (in.) were you mowing at the highest setting? I’d say with your raininess and temps, 3-3.25” would be a good HOC to help dry it out and not harbor any more disease.
The highest setting has the blade about 3.25" above the ground. The grass is currently 4".
I was thinking of letting the grass grow out to 5" or a little more before cutting it back to 2.5" or 3". This is based on a suggestion I read online to let the fungus on the grass blades grow to the tips before cutting and bagging so that the fungus doesn't stay on the ground. Do you think this is better than following the 1/3 rule for this one time?

JHazzardB
Posts: 417
Joined: August 7th, 2012, 11:16 am
Location: OKC, OK
Grass Type: Front Yard: KBG blend. Back Bewitched/Nuglade
Lawn Size: 5000-10000
Level: Experienced

Re: New Sod Wiped out by Fungus

Post by JHazzardB » June 15th, 2020, 2:12 pm

I think the introduction of a new fungus resistant grass would be a great idea.

I think a good organic fertilizer (1/2 strength) would be okay considering your lower temps. I'm not familiar with your climate or if your yard goes dormant or gets stressed out. Smaller doses should be okay. We'll see if anyone else chimes in to stop that advice though.

I'd keep mowing regularly at the highest setting. With your weather right now, I'd keep trying to maintain that height to encourage it to stay dry and fill in by tillering.

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