Question
QUESTION: New home, Newly sodded St Augustine lawn 6 mos old.  Have developed a large 6 ft in diameter brown ring in back yard.
Have treated with both a fungicide with no results
and then chinch bugs.  Neither helped.  thank you

ANSWER: Clay:

There are several diseases and pest which attack St. Augustine.

The brown ring would seem to be a fungus.  Fungicides will stop a common invader, but the grass will need replacement, seeding, sod, or plug to recover.

Brown patch, downy mildew, anthracnose, rust, take-all root rot and grey leaf spot are regular fungi on St. Augustine.  Preventative fungicide treatments, careful moderate watering and moderate fertilization are cultural practices which favor the grass over the fungus.

Insects are cinch bugs, white grubs, sod webworms, army worms and cutworms.

I do not know where you are, so I do not know what weather effected growth and health.

Is the spot growing?  Have you replanted in the damaged area?

If the agent is a fungus, you will need to treat in winter and again in spring.  There is a natural treatment for cinch bugs called Mycotrol-O with a virus which attacks cinch bug larvae, reducing population.  It re-introduces Beauveria blissus into the soil and effects the grubs.

Hope this helps.  Best wishes.


---------- FOLLOW-UP ----------

QUESTION: Thank you.  We live in Caldwell, Tx. Have a water sprinkler system and was watered daily for 15 mins for new yard. Now is watered 2 times week.  Ring is much larger than two months ago.  We have fertilized with 15-5-10 twice in 6 mos. applied Scotts fungicide and 3 wks later wal-mart cinch bug granules.  Should I apply winter fertilizer and or any other treatment.  Thank you very much

Answer
Clay:

Try leaving out fertilization for the winter months   Too much fertilizer will promote some fungi.  Further, do not overwater.  Apply irrigation in morning when moisture may evaporate during the day.

See how this effects the ring in spring.  Cooler temperatures should slow fungus growth.

Below is a list of fungicides for brown patch.  Some of these also work for other fungi as well:

azoxystrobin
captan
chloroneb
chloroneb + thiophanate-methyl
chlorothalonil
chlorothalonil + fenarimol
cyproconazole
fenarimol
flutolanil
iprodione
mancozeb
maneb
myclobutanil
PCNB
propiconazole
pyraclostrobin
thiophanate-methyl
thiophanate-methyl + iprodione
thiophanate-methyl + mancozeb
vinclozolin

Scott's fungicide seems to contain one or more of these depending on which formula you bought.

Best wishes.