Monday, June 8th, after the tropical storm rains stopped, I took a walk in the yard and noticed my back yard St. Augustine had what looked like grey leaf spot fungus in several areas. Wednesday, June 10th I cut the grass and then on Saturday, June 13th, I applied Propiconazole 14.3.

I’ve been keeping an eye on the lawn since and each day since I sprayed it’s appeared alot yellower in color from a distance so today I went and took these close ups. I noticed what looks like St Aug decline. Comparing the color of the established grass to the new sod shows the yellowing, pics don’t really do it justice.

What should I do now? Is it normal to see an excessive yellowing after applying fungicide?

I just mailed off soil samples yesterday to LSUAg. I fertilized w/ 24-2-11 in late April.

pics

Edited dates

This post was edited on 6/17/20 at 9:13 am

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Posted by ronk

Member since Jan 2015

7559 posts

Posted on 6/16/20 at 11:55 pm to good_2_geaux

There is a lot going on in the pics. Sod, plugs, established sod, some of that dirt looks like cement, shredded leaf blades from the mower.

Yellowing is not caused by fungicide. New sod will get worse before it gets better. Keep it wet for 2 weeks.

Did you plug your yard as well?

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Posted by good_2_geaux

Member since Feb 2015

802 posts

Posted on 6/17/20 at 6:03 am to ronk

I’m worried about the established grass only.

I took a pic showing the sod to show the color difference only. Sod is that traditional dark green (healthy), established grass - yellow.

The runner is on concrete. I pulled the sickest looking runner out to look at.

This is a house we bought 2 months ago. I tilled, smoothed, and laid sod on 2/3 of the back yard 3 weeks ago

The established grass looks sick

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Posted by Farmer Joe

Member since Jun 2020

74 posts

Posted on 6/17/20 at 6:43 am to good_2_geaux

It’s iron deficiency. Fungicide should help with the grey leaf spots.

This post was edited on 6/17/20 at 6:44 am

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Posted by ronk

Member since Jan 2015

7559 posts

Posted on 6/17/20 at 7:41 am to good_2_geaux

I'm a moron. That's what I get for replying late at night while zooming in on my phone. It's not chlorotic. Chlorosis looks different. There is some leaf spot fungus but I don't think that is causing the issue. In that one picture with the black runner it would be a root rot fungus. Not take all patch because it's solid black and not just black lesions. Typically that type of solid black means the root system was underwater for too long and the plant could not exchange oxygen. Try watering only when the grass shows signs of drought stress.

What type of herbicides have you used this year?

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Posted by good_2_geaux

Member since Feb 2015

802 posts

Posted on 6/17/20 at 8:26 am to ronk

The root rot makes sense. The area it was pulled up in stayed wet. Ive since added gutter downspout drains and underground pipes to divert the water that was making that particular area pool up with rain water. Hopefully it helps.

Herbicides: atrazine and 24D the day after we moved in ~10 weeks ago.

My backpack sprayer prior to the fungicide application had celcius and sedgehammer mix that I used on the front lawn. I rinsed it out well and dont think it was from leftover chemical. The yellow is too consistant throughout the lawn.

I do have some iron I can apply.

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Posted by baldona

Florida

Member since Feb 2016

23743 posts

Posted on 6/17/20 at 8:31 am to good_2_geaux

I just came to say your dates of 6-8-20 in a grass thread made me think you we’re talking about a fertilizer ratio

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Posted by good_2_geaux

Member since Feb 2015

802 posts

Posted on 6/17/20 at 9:13 am to baldona

quote:
made me think you we’re talking about a fertilizer ratio

edited

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Posted by TheWiz

Third World, LA

Member since Aug 2007

11872 posts

Posted on 6/17/20 at 9:33 am to ronk

quote:
picture with the black runner it would be a root rot fungus. Not take all patch because it's solid black and not just black lesions. Typically that type of solid black means the root system was underwater for too long and the plant could not exchange oxygen. Try watering only when the grass shows signs of drought stress.

I keep having the same damn issues. In the backyard a large patch of St. Aug is invading my Zoysia. As of late, I have had random dead spots and long runners of dead, black grass. I nuked it with Liquid Systemic Fungicide II. Was that the wrong move? Yes, I have been watering a fair amount when I see a week of no rain. My Zoysia has never looked better besides the dog piss spots I cannot beat.

This post was edited on 6/17/20 at 9:45 am

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Posted by baldona

Florida

Member since Feb 2016

23743 posts

Posted on 6/17/20 at 10:29 am to TheWiz

When my St Aug is long, 3.5-4.5". I'll cut it at 4" sometimes so its over 4" between mowings. Then the ground holds moisture really well. If you have other grass say in your front yard, you may consider doing multiple stages of waterings. Water your front Centipede 3 times a week and St Aug twice. Or something like that.

Generally speaking grass is : Water, sun, and proper cut. If you are having issues one of those 3 are likely off.

Fert and other things defintely help, but one of those three above are likely off if you need something applied to an otherwise healthy lawn.

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Posted by jmtigers

1826.71 miles from USC

Member since Sep 2003

4990 posts

Posted on 6/17/20 at 10:40 am to ronk

quote:
Try watering only when the grass shows signs of drought stress.

This. LCN called it rain drunk st aug after a trop storm in his area. First mow after increases the yellowing.. Applying fungicide as well only made it yellow more.

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