Red Thread Lawn Disease

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Red Thread Lawn Disease

Have you ever had a brown patch with a reddish tinge on your lawn and wondered what it is? If it’s not spray paint or your kid’s paintball gun, it’s probably red thread lawn disease. Red thread is not the deadliest lawn disease, but you don’t want to take it lightly. Severe cases of this disease can kill the grass completely.

Red thread lawn disease is common in red fescue grass and perennial ryegrass. Bermuda, bentgrass and Kentucky bluegrass are sometimes affected.

The affected areas appear in irregularly-shaped patches of a reddish or pink complexion. It is difficult to identify red thread disease until the more advanced stages of disease development. This stage is when bright coral pink fungus mycelium reaches a length of 1/16″ to 1/4″ at the tip of the damaged, thin and wiry leaves.

This fungi spreads by moving mycelium or infected leaves to new areas. These fungi can also be transported by your lawn mower because the mycelium on grass is easily broken loose. The ideal development of red thread occurs between temperatures of 65 and 75 degrees Fahrenheit.

How Do You Get Rid of It?

Get out your fertilizer. Adding more nitrogen to your lawn usually reduces red thread disease. However, having a higher level of nitrogen can cause other disease damage such as leaf spot and brown patch. In most cases, a fungicide treatment is unnecessary, but wet weather can sometimes cause severe damage. In this situation, a fungicide would help reduce symptoms.


Author Bio

Matt Morrison is a lawn expert, homeowner, and website hobbyist from Texas. He enjoys working on his own lawn and helping others make their lawn the best it can be. You can read more of his articles here.

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  1. Thanks alot for this wonderful post! I’ll be sure to check out the rest of your site!

  2. Thanks a ton. Do you have any recommendations for fungicides to use. I live in North Central Oregon and began getting this disease last summer. It just won’t seem to go away with nitrogen treatments only.

  3. I’m not familiar with that area, but your local extension office should be able to help. Otherwise hit up your local home and garden store to find fungicides. The labels usually tell which diseases they treat.

  4. Lisa Hanrahan

    This is very helpful. I live in Connecticut and we’ve had a lot of rain and cool temperatures this spring. After mowing my lawn last week I began to notice a red tinge to much of the lawn. Is there a particular fungicde you would recommend to help control/eradicate this fungus? Thanks for your assistance.

    • Lisa,

      You could try Bayer Advanced Fungus Control for Lawns RTU Granules (triadimefon) or any fungicide at the store that includes the active ingredient propiconazole. Good luck!

  5. Eric S. Mitzelfeldt

    We have red thread that continues to get worse even with nitrogen which makes the good grass really grow. Would thatching help reduce the effect of the red thread and what else can we try? We live in Western Washington about an hour north of Seattle. Thanks for your help, Eric

    • Eric,

      Excess thatch can contribute to disease development. If you have more than 1/2 inch of thatch, then I recommend removing it with a thatching rake or power dethatcher. You can also apply a fungicide (like the ones already suggested in comments above) every 7 to 21 days during moist weather in the spring or fall.

      • Eric S. Mitzelfeldt

        Thanks so much. It has been a very wet & cool spring here, the next two days are supposed to be nice so will get out & thatch the lawn. Thanks again, Eric

  6. Matt-

    I live in Maine and just bought a home last year that had a great green lawn until a few weeks ago when I noticed what I thought was browning but have been recently told its red thread. will the lawn come back without fungicides? I have read conflicting reports online… waterly deeply and often and then also cut back on watering. which is it do you think? I have an irrigation system that waters each morning and recently bumped it to 30 min per zone which is really soaking it now. is that worse? should I do every other day?

    • Dave,

      Your lawn can survive red thread without fungicide, but if it looks pretty severe you should apply a fungicide. DO NOT water your lawn everyday. Really soaking the lawn is good, but not every day. Slowly cut that back to once a week if you can. The correct answer for when to water is when it needs it. Let your lawn show you when it’s ready for irrigation. It will turn a grayish-green color, the leaves will shrink in size, and footprints will stay in the lawn after you walk across it. Good luck!

  7. i live in newhampshire and my lawn has never looked good at all sinse i moved here in 2010 that was when the lawn was sprayed on f finally got a lawn company to come out and he picked right up on the red thread and advised to bag my clippings and he sprayed a funguside

  8. I live in Pa and this spring was wet and cool, should I pick up my grass clippings and how high should I move my lawn. I have red tread in some spots of my lawn more this year than ever. Thanks

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