How to Identify and Control Red Thread

This article recently appeared on Scott’s website, for the full article click here: https://www.scotts.com/en-us/library/lawn-disease-control/how-identify-and-control-red-thread Here are some ways to be confident you have red thread, plus tips for getting rid of it.

The first time you see a red-pink patch of grass in your lawn, you may think it’s just the way the light is hitting it. But when you take a closer look, you may notice that it’s different from your normal green grass. The cause could be a grass disease called red thread, named for the reddish pink, spiky threads often found clinging to, or extending from the tips of, the grass blades. Those blades may even have small, cotton-candy like strands wisping around them.

Red thread certainly has a distinctive look to it, but it may still be hard to identify if you are unfamiliar with the disease. Here are some ways to be confident you have red thread, plus tips for either reducing the severity of the disease or getting rid of it altogether.

1. Positively identify the disease as red thread.

Among the first lawn diseases of the growing season, red thread is extremely common in spring but can appear in fall in and winter as well. (Red thread can also be active through the winter in the mild, wet climate of the Pacific Northwest.) Cool, wet weather and prolonged overcast conditions create the ideal environment for it to thrive.

In addition to the pinkish-red color, lawns affected by red thread have grass blades that look ragged and seem to be dying back from the tip of the leaf. The affected grass will appear in irregularly shaped, straw-like patches that range in size from 2 inches to 3 feet in diameter.

The red, thread-like strands that may also be present appear more often in later stages of the disease. You’ll notice brittle, antler-like strands extending ¼ inch or more from grass leaf tips. When grass is wet, red thread appears darker red in color; when dry, it looks more pink. The best time to look for red thread is in the early morning when there’s still dew on the blades. As red thread disease continues to progress, you may also see a pink, gelatinous growth on top of grass blades.

2. Understand what causes the disease.

Red thread is caused by the fungus Laetisaria fuciformis. Undernourished lawns are more susceptible, as are lawns composed of these grass species:

• Bentgrass
• Bermudagrass
• Fescues
• Perennial ryegrass

3. Practice basic lawn care.

One of the causes of red thread, and a contributor to its severity, is poor, under-nourished turf, so your first line of defense is to give your grass regular care by:

• Feeding your lawn regularly with the right fertilizer for your grass type.
• Watering your lawn properly.
• Mow your lawn routinely, keeping it at the ideal height for your grass type.
• Aerating and dethatching your lawn every few years, as necessary.

One more thing that may help is to overseed your lawn each year with high quality grass seed that has improved varieties. This is especially helpful if your lawn is 10 years old or older.

4. Control the outbreak and repair the damage.

If red thread disease continues to be a problem in your lawn, treat it with a fungicide, following all label directions. A broad-spectrum fungicide product kills the active fungus while helping prevent the spread of, and reinfection from, the disease for up to 4 weeks. For best results, apply the fungicide when temperatures range between 60 and 75 degrees F. To control red thread, you may need to re-apply, depending on the severity of the outbreak.

Like other lawn diseases, red thread will likely leave behind some damaged areas that may need to be patched. Reseed once you have the disease under control.

With the right care, you’ll make it harder for red thread to move in and affect your lawn.