Question

lawn photos   QUESTION: I would like a diagnosis and treatment recommendations for a problem that my lawn has recently developed: numerous small bare spots. Here are the details.

Lawn starts about 50 yards from the Atlantic ocean, Bahia, Brazil.
Grass type: Zoysia 揺merald? Installed (as sod) 6 years ago.
4?topsoil on top of sand.
Tropical climate (never lower than 65F). Annual rainfall: 70?
Lawn has full sun for 6-8 hours a day.
Underground sprinklers, run twice a day for 8 minutes each.
The lawn has never been overseeded. Fertilizer has been added once a year.
No problems until about 3 months ago.

Symptoms:
- Numerous, mostly small (1?to 4? bare spots. (Photos 1 thru 6)
- No signs of damage on adjacent grass blades. (Photos 2, 3)
- In some of the bare spots, the earth is now clotted and rock-hard. (Photo 8)
- Occasionally in early morning there are cobweb-like tuffs on many spots. (No photo)
- Not all of the lawn is affected. (Photo 7)
(Note: photos on attached file run left to right, beginning in upper LH corner.)
Thanks!

ANSWER:  The only and tentative conclusions I can make are:
You may have an infestation of sod web worms. (Webbing on the turf early am.)
Something of significance - natural or man made - must have occurred to cause the development of the symptoms of three months ago.


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

QUESTION: Hi Ronald -
Thanks for the quick and helpful reply. I'll check re the sod web worms.

I see I forgot to mention that for the last few months we've been having unusually heavy and frequent rain, so much so that some of the lawn seems spongy under foot (and it's never been like that before). Could that be the 'something of significance'?

Thanks again,
  Frank

Answer
With heavy rainfall, we can probably discount insect damage. Tnat leaves us with fungus - except that I cannot relate the symptoms with a knowm fungus disease. If you live in the USA you can get free help from your County Extension Office.