Our lawn has several large dead spots. One is about 4' across on the sunny
part of the lawn, another is about 2' across on the shady part of the lawn
and a third consists of a bunch or small circles that have not YET joined
together to form one big dead spot. These spots started appearing about two
months ago or perhaps more correctly never recovered from the dry spring
like the rest of the lawn. I fertilized in late May and did not start any
watering until mid June.

The nominees for the dead spots a

1) Dry spring. I started watering too late and some patches never recovered.
But I never watered the back lawn (shady) and it has recovered nicely after
the recent rains.

2) Fertilizer burn. Perhaps, but the telltale bright outer ring is missing
and no amount of watering has helped this. Also, the same dufus (moi)
fertilized the back and front lawns.

3) Crappy sprinkler coverage. We had one impact sprinkler that I moved
around and there is no question that it misses spots. But this has not been
an issue in other years.

4) Mould or Fungus. I have no experience with this.

5) Grubs. This seems to be the opinions of neighbours and others, but the
Skunks and Raccoons do not concur. Also, I have excavated two 1' square
patches, one in the dead zone (3 weeks ago) and one outside the dead zone a
few days ago. I found ZERO grubs. Perhaps I waited too late to dig up a test
patch, but we have had no Skunks or Raccoons digging up the lawn like other
years. We have also had the lawn treated with Merit several years in a row,
although not last year.

Your advice would be appreciated. I'm leaning toward a combination of 1 & 2,
but I have no experience with Mould.

We recently had REAL sprinklers installed, as we plan to put some soil in
the dead spots and seed them. But I'd like to solve any underlying problems
before I do this.

I'm in Zone 6A (Southern Ontario)