How do I know if brown patches in my lawn are due to over fertilizing or grub activity?

Question

There is a possibility I over fertilized. The brown patches are in only one zone where I did an extra application of fertilizer.

Answer 1

If brown area is soft and spongy, it can be grubs, As the other person says, lift the grass if it is loose and check. Also, doggy pee will cause the brown patches also.

Answer 2

It could be that you did put down too much fertilizer. I would also check for grubs. To do this you can dig up a few 1'x1' spots in random areas that are affected. You only need to dig down about an 1-1/2". If you find more than one grub in any one of those samples,  then you will have to treat. Not just that area, but the entire lawn. If no grubs then you should water a little more in that area to wash the fertilizer down. I'm not sure what you put down, but you might want to consider a slow release fertilizer for future use. Good Luck.

Answer 3

It very well could be because you over fertilized it. It also might be because it is drier in that part of the lawn. The grass may have been shorter and unhealthy because it was too dry, and that may have caused you to over fertilize it.

Answer 4

You would be able to tell if it's grubs doing the damage:  lift the brown patch up and if the brown grass comes off easily, it's the grubs.  Grubs eat grass roots which kills the grass (= brown grass).

The grubs will be just at the root surface and you may be able to see some still there, if they haven't morphed into June beetles yet and flown away.  (this is the season for beetles)