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TARR: The Deadly Fungus That's Killing Your St. Augustine Lawn

Updated: Sep 20

Take All Root Rot


Take all root rot fungus in St. Augustine lawn
St. Augustine grass with extensive TARR damage. Note the characteristic dead stolons (runners).

What Is Take All Root Rot?

Take All Root Rot fungus (TARR) is the most common cause of sod problems in St. Augustine lawns in North Texas. The TARR fungus lives in the soil and attacks the roots of St. Augustine grass, literally rotting them and depriving the grass of the ability to take up water and nutrients from the soil. The result is dead patches of grass, eventually leading to areas of uncovered soil and the proliferation of weeds in those areas.


When surrounding grass attempts to grow into the bare patches, the fungus rots the roots off the pioneering stolons, making it impossible for the area to recover. Re-sodding an area that has been killed by TARR doesn’t work either. The fungus is in the soil and just attacks the new sod.


How to Identify TARR

Symptoms of TARR problems appear in the new sod in a year or two and the new lawn is soon as bad off as it was before. TARR is primarily a problem for St. Augustine lawns, although it can sometimes attack Bermuda lawns as well.


St. Augustine Stolon infected with take all root rot
Dead St. Augustine stolon showing how the roots have died and rotted off.

TARR typically develops in low areas that stay damp during the night, particularly in the Spring and Fall. You can recognize TARR by noting areas of thinning grass with dead runners. Development is generally slow and it may take years for an entire lawn to disappear. Grass that is experiencing multiple stresses – shade, drought, excessive heat or toxins – is more vulnerable to the fungus. This may make identifying the problem more difficult.

 

TARR is sometimes confused with loss of grass from insufficient sunlight, brown patch fungus, and chinch bug infestations, all of which plague North Texas lawns. It is often necessary to examine the history of the lawn in order to determine what problem or problems it faces.


Switch to an Organic Program

TARR is less of a problem in lawns maintained organically, as opposed to those on which chemical fertilizers and herbicides are used. There are microbes in healthy soil that eat the fungus and are generally able to keep TARR problems under control. Chemical fertilizers and weed & feed products kill these microbes, leaving the lawn defenseless against the fungus. Healthy soil makes for healthy plants and damaged soil makes unhealthy plants.


Lawns with TARR fungus are often treated with chemical fungicides. These mitigate the problem but they don’t solve it. They treat the fungus in the plant, but not in the soil. The grass recovers somewhat, but soon becomes re-infected by the fungus in the soil. Keeping the grass alive then requires repeated applications of chemical fungicide as often as once a month. Besides, chemical fungicides often kill off beneficial fungus species reducing the quality of the soil.


The only long-term solution to the TARR problem is to stop using all chemical fertilizers and weed & feeds. Chemical fertilizers provide food for the plant but do nothing to improve the soil. Organic fertilizers, on the other hand, enrich the soil so that it can supply nutrients to the plants. Beneficial microbes can then repopulate the soil. This process can be hastened by applying composts to the soil that restore the necessary microbes.


If your St. Augustine lawn is in poor health it could be infected with Take All Root Rot. It's important to act quickly before you lose your entire lawn. Our landscape services department is ready to help you determine the cause and the solution to all your lawn problems. Give us a call us to schedule a consultation today.


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