Question of the Week – Number Two: April 9, 2020

“Why is my St. Augustine so anemic looking? What can I do?”

There have been recent days when this question has made up half of my emails and phone calls. (Most of the other half were the frozen crape myrtles I covered in this week’s other question!)

Let me address this question’s answer the quick way.

Dewitt M. posted this example of TARR on my Facebook page.

Take all root rot…
Soil-borne fungus that causes death of the lawn’s roots.
Attacks primarily St. Augustine, but also zoysias.

You can see the yellowed blades in affected area.

Grass is yellowed in irregular patches but does not respond to fertilizers.
Runners have browned, stubby roots.
Runners pull loose from the soil easily, almost as if grub worms had been involved, but grub worms are seldom found in the soil.

Continued Below

Characteristic yellowing of grass blades is evident, even to the point of killing a large patch of grass.

Affected areas can be in sun or shade.
TARR is a cool-season disease that appears in April and May. It is not present in lawns in hot summer weather.
TARR is worst in alkaline soils, hence the old (now outdated) recommendation of applying a 1-inch layer of sphagnum peat moss to provide an acidic layer on top of the soil. However…
The best remedy is application of the fungicide Azoxystrobin. It is found in nurseries and hardware stores. Ask a garden professional to help you, and look for that name on the container.
Grass should show improvement within 1-2 weeks after treatment.

Posted by Neil Sperry
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