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Lawn Disease: Is that Cotton Candy on my Lawn?

Spring can be a very inconsistent season. Some days are warm and beautiful and some days are wet, cool, and dreary. Lawns are especially susceptible to all sorts of pests in Spring, including fungus and disease.

Two such fungi are known as “Red Thread” and “Pink Patch.” Both appear as irregularly-shaped patches in the lawn. Both have a red or pink cast to them. Both usually only affect just the leaves (blades) and stems of the grass plant but can kill the entire plant if left untreated.

How to Spot Lawn Disease

When looking at and identifying any lawn or grass disease, it is best to look at the entire area from a distance and also look at the disease and plant close-up.

Standing back and looking at the affected area, Red Thread appears as a reddish-pinkish color in an irregular pattern. The fungus can be multiple small spots or the spots can bunch together and look like a large patch.

Close up, Red Thread literally looks like little red threads coming out of the grass blades. These “threads” are somewhat hard to see, but getting down close to the grass (or picking up a handful) will help. The “threads” are very thin but visible to the naked eye.

Red Thread will be bright red when the disease is active. It will fade to pink when in a dormant state.

Pink Patch looks just like tiny cotton candy throughout the lawn. It is not as bright red as red thread, but it is pink when active. It fades to a straw-like color as it goes dormant. Pink Patch also looks reddish brown from a distance.

The Science Behind Red Thread and Pink Patch

Both of these pathogens overwinter, or survive through harsh winter conditions, in the thatch layer on dead leaves or in clippings from the previous year. They become active as the spring weather arrives with prolonged periods of rainy or humid weather and temperatures between 65 to 75 degrees F. They enter the grass leaves through natural openings and cut tips and spread throughout the leaf.

In many cases, lawns with adequate nitrogen levels will have less problems than those with low nitrogen levels. Healthy turf can better withstand the infection and grow out of the damage once the weather conditions change.

In severe cases, fungicides may be warranted for Red Thread and Pink Patch. Repeated applications may be necessary to slow down the disease. The disease symptoms may not subside until the weather conditions cooperate. When the diseases do go dormant, there may be yellow patches left behind that may need some overseeding.

One important tip—these lawn pathogens are manageable but very often recur yearly.

Has your lawn been green and lush or full of surprises this Spring? Share your story in the comments!