Grass turning purple? Ideas?

RichS · Jul 19, 2019

Twenty years caring for my lawn and I've never seen this. Much of my lawn is showing brown patches. With the recent heat wave and most surrounding lawns browning, I attributed it to heat stress. But it's quite odd that it's in patches and not all over.

Then in one area of the lawn - about a 15 foot strip between the driveway and the neighbor's lawn, it's turning distinctly purple. I tackled red thread a couple of months back with Azoxystrobin, but I'm not sure it's a good idea to spray that again with 90-95 degree days coming up. Fwiw, I also have propoconizole.

It's been about 7 weeks since my last application (25-0-10, a bit of left-over Urea, SOP, and Milorg with micros - net of 1lb N, .15lb P, .75lb K per thousand square foot). So it may be starting to be starved for N, but I rarely, if ever, apply any in the heat of the summer, and have never seen this before.

From where it is and how it's growing, it doesn't look to be an invasive weed - just discoloration of the TTTF grass. But I couldn't find any fungus/disease descriptions that included purple. Any thoughts on what this may be?

Darrell_KC · Jul 19, 2019

Its not the same issue, but I know that KBG is a cool season grass that can also turn purple, and its a sign of drought/heat stress. I dont know if your TTTF is behaving in the same manner

SixString · Jul 19, 2019

Brown patch and red thread. Tough combo to fight simultaneously.

KoopHawk · Jul 19, 2019

It would be freaking awesome if you could get the entire lawn to turn purple. You could start the Kentucky Purple Grass revolution!

Chris LI · Jul 19, 2019

I hope I'm wrong with the ID, but I think that you have an infestation of Poa Trivialis (Roughstalk bluegrass). It goes dormant with the heat of the summer and comes back in the fall. It spreads by stolons on the surface, and you can peel the turf off the surface. The only herbicide that is effective is glyphosate, which is best applied in the spring when it's actively growing. There is a great YouTube video on IDing Poa T, from Tom Green. I unfortunately discovered that a good portion of my backyard is infected/infested with Poa T. It is a multi-year battle, from what I understand. Good luck!

OnyxsLawn · Jul 19, 2019

Purple grass can be a sign of P deficiency but I don't think it would present in patches like that.

g-man · Jul 19, 2019

Is this the only area like this in your or your neighbor's yard? This is odd looking.

craigdt · Jul 19, 2019

I also wonder if that isn't a different type of grass.

RichS · Jul 20, 2019

If KBG does this, that may be the cause. I overseeded with TTTF, and that's most of the grass, but that was over top of whatever was here when I moved in - only a year after the house was built so probably a hodgepodge of cheap seed from the contractor

Getting on my knees for a closer look, the brown stuff is certainly much finer than what's still green. I managed to find mostly still-green versions of what I think is the brown - thoughts?

Here is a clump of the brown grass and then a clump of what's still green.

Grass turning purple? Ideas?

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