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I live in zone 9b, South Texas. For two springs in a row, I've been having an issue whereby patches of my Zoysia grass starts turning red. Over time, the grass flattens and loses density. The blade tips themselves seem to lose their green and turn red. I'm fairly certain it's not rust fungus. There is no powdery substance on the blades and nothing "comes loose" when rubbing the grass. I've performed numerous troubleshooting and am at a loss for whats causing it:

  1. Ensured proper water coverage. Not only tested with cat food cans, but also drummed up a map and calculated water coverage. I do one deep water a week. No more. Also use a smart irrigation controller which automatically adjusts based on weather conditions.
  2. Mow every 7 days, never taking off anywhere near 1/3 of grass blades.
  3. Aerate and top dress with compost/sand once a year. I follow an organic fertilizing program. This year, I'm trying Milorganite. Last year did Medina/Milorganite mix.
  4. I've only used pre-emergent herbicide twice in 2 years. Otherwise I only hand pull weeds.
  5. The only insecticide I use is Grub-Ex. Haven't spread it yet this year.
  6. Tried spraying Ferilome Fungicide last year. It didn't work.
  7. I've even taken soil samples to ensure what my deficiencies are. Soil stats:
    • pH 8.0
    • Low N, P. High K
    • High Mg, S, Zn
    • Normal Mn, Cu
    • Extra high Ca
    • Extra low Na

I know my soil stats aren't the best, but I also have Bermuda grass and it never has this red bladed issue. Solely isolated to my Zoysia. Any ideas on what's happening would be greatly appreciated.

Single Red Blade Red Grass Blades Red Patch

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  • What have you been using for fertilizer? MiloOrganic is not a balanced fertilizer. This reddish color usually indicates phosphorus deficiency. Your test was wonderful, good for you! Your pH is way way too high. Your lawn pH needs to be brought down to 6.5. That is usually a sulfur product. But first, what else have your added, what fertilizers up to now, how often, aeration, thatch amount...otherwise the grass looks healthy, except for the color. I do not know warm season grasses very well and management is so different! I am learning more than I think I wanted, however, grins!
    – stormy
    May 1, 2018 at 7:29
  • Using any other product other than fertilizer on your lawn can make problems far larger. Do not use grub control. It is not a preventative. Grub control in my experience kills everything in the soil and kills the very organisms that keep grubs in check. The next year...total devastation. Brand new lawn. Never ever use pre emergent herbicide. Again, not at all a preventative. MiloOrganic will only push the Ca and Mg higher. Already too high. Too low in Nitrogen? Too high in K? The one part of the miloOrganic formulation not present?
    – stormy
    May 1, 2018 at 7:37
  • Which USDA zone are you in, or where are you?
    – Bamboo
    May 1, 2018 at 11:05
  • I haven't added sulfur to lower pH because my soil already has high levels of it. Hoping the top dressing eventually brings it down. Only ever added milorganite and medina. I fertilize 4 times a year. I choose only Milorganite this year because it's the only fert to not have any K. Figured better to go over on Ca and Mg instead of the K? My neighborhood gets devastated with June Bugs every year with my porch always getting littered with them. Everyone's lawn suffers. Grub control helps reduce the damage and numbers my lawn experienced.
    – Ifrit
    May 1, 2018 at 17:36
  • I'm in zone 9b. South Texas.
    – Ifrit
    May 1, 2018 at 17:36

4 Answers 4

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Well I was thinking this might be a case of fusarium patch disease, but where you live that shouldn't be an issue, unless you've experienced wet and cool springs, or your lawn has too much nitrogen in the soil beneath. Other than red thread, which doesn't affect Zoysia, fusarium patch is the only thing I know that turns grass blades red. If the lawn has these reddened stems in more or less circular areas, then it might be that, more information here http://homeguides.sfgate.com/sod-diseases-32402.html

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  • After reading around about fusarium, I don't think it's that either. Definitely not red thread either.
    – Ifrit
    May 2, 2018 at 1:20
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In the end, I believe this is just a case of poor nutrition. I spread compost over some of the afflicted area and after a few weeks, the red tips disappeared. As to what nutrient was lacking...I'm not sure.

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I'm in James Island (Charleston), SC - Zone 9a.

I had a similar question earlier this year, and my landscaper told me this is typically what happens when new grass blades are "born" into a cold/cool environment. If you've had some cool nights/mornings while the grass is still coming out of dormancy, this could be why you are noticing purple tips.

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First you have Empire Zoysia, The red color in the leaf blades indicate two much water or can be from cold nights. Your pH should be 6.0 to 6.5 get that down. Second, Empire Zoysia calls for a 1-0-1 ratio fertilizer in spring like 15-0-15 than a 1-0-2 ratio in late summer fall like 8-0-16. Empire zoysia doesn't need much fertilizer but you should be giving it more. Third I would recommend a topdressing of sand after verticutting or areation, not heavy but lightly to cut down on thatch a little more after which one you choose. Four I would also recommend a Fungicide before you do get a disease to be safe.

Just Google Empire Zosyia and the you should find great maintenance practices for your lawn oh also SHARPEN YOUR MOWER BLADE you need to do that, and do it about every 20K sq ft cor your lawn to have the best chance at being it's best, it will cut down on poor cutting which can lead to disease

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