Question of the Week – Number 1: April 23, 2020

“My St. Augustine is really coming out strangely. Part is yellowed. Part is green. And part is completely dead. What gives?”

That’s the perfect description of take all root rot, an increasingly common fungus in St. Augustine and zoysia turf.

This photo by Laura M. was posted on my Facebook page recently. It shows the impact of this fungus.

The things you need to know about TARR…
It’s a cool-season disease that’s most prevalent in late March, April and May. If something shows up in June or after, it’s probably something else.
Attacks primarily St. Augustine, but also zoysia.
Much more common in areas with alkaline soils.
When viewed from the side and from 20 or 25 feet away, the grass will have diffused yellowed areas, while other portions will remain green and vigorous.
Affected grass pulls loose from the soil easily. Roots are short, dark brown nubs. They are rotted and dried looking. Some people will suspect that it’s grub worm damage, but when they dig they rarely find any at all, let alone enough to cause this discoloration.

Continued Below

This St. Augustine is getting the double whammy. Too much shade is weakening the grass up around the tree’s trunk, but then take all root rot is taking down much of the rest. Serious corrections are probably going to have to be made.

Old recommendation was to rake out a 1-inch covering of brown sphagnum peat moss to provide an acidic layer on top of the soil. That helped suppress the fungus, but then pathologists announced that the fungicide Azoxystrobin (sold to consumers as Scotts Disease-EX and applied by professionals as Heritage) was even more effective because it actually kills the TARR fungus. If you apply the fungicide now you should see results within just 2-3 weeks.

Posted by Neil Sperry
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