What are the red and pink patches in my lawn?

Olympia & DuPont Lawn Care Maintenance

Red thread is a turfgrass disease also known as corticium disease or pink patch.  You notice the red, thread-like structures at the tip of the leaf or pink mycelium at the edges of a straw-colored patch.

The dormant disease overwinters on the leaves and thatch layers of previously infected plants and can remain viable for over two years.  The thread-like structures break loose and can be carried by the wind.  Mowing plays a relatively minor role in spreading the disease.

Conditions are favorable in the late spring/early summer and late summer into the fall.  Ideal temperatures in the 68-75 degrees F range with extended periods of moisture or high humidity.  Other contributors are low fertilization, compacted soil and excessive thatch.  Red thread is common on new lawns hungry for fertilizer.

What can you do?

-Fertilize regularly to improve plant recovery.

-Keep mower blades sharp to reduce plant injury.

-Aerate compacted lawns.

-Remove excessive thatch.

-Over-seed with disease resistant 3-way perennial ryegrass.

The good news is that red thread is a foliar disease so it only attacks the leaves of the grass plant, leaving the crown and roots unharmed.  It is not necessary to apply a fungicide.  We prefer to grow our way out of it with a solid fertilizer plan.  Conditions that are favorable to red thread like temperature or moisture will change and the lawn will recover.


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