Brown Spots Emerge In Fescue Lawn In Midsummer

The lawn with brown and dead spots

Q. I need your assistance. Below photo depicts the present condition of my backyard. It has patches of dry or dead grass. I don't know what caused the problem. Is there some way to revive the grass without going to the extreme of re-sodding? And what shall I do to prevent this in the future?

A. Thanks for the picture. The picture helps and it doesn’t help. It would have helped if I saw something in the picture that gave me a clue. But there is nothing in the picture that is distinctive to me. It would be interesting to know if those dead spots were in any kind of pattern in relation to your irrigation heads.

I did notice in the picture that whatever caused the damage appears to be gone. The grass around the dead areas seem to be thriving. This would tend to eliminate irrigation as a problem unless you changed your irrigation schedule. If these dead spots occur in the same spots year after year it is usually associated with irrigation. I tend to think it is either insect or disease problems from your picture.

Lawn with poor irrigation overlap
from sprinklers

Let me just point out some weaknesses in the design that might contribute to the current problem. I tend to discourage homeowners from designing a turfgrass area in other than straight lines. I know this might be somewhat boring but water from sprinkler heads is thrown in straight lines. Irregular lines or curving lines tend to cause those areas inside the curves to be under watered or the areas outside the curves, and no longer in the turfgrass, to be overwatered.

I noticed in your picture that most of the damage is closest to the non turfgrass area while the solid turf area is less damaged. Another point, those areas of the turfgrass closest to rock mulch, sidewalks or patios in full sun tend to use more water than those areas deep inside the turf area. These areas, close to bare ground or rock mulch, tend to be warmer and more prone to insect attacks than others. Insect damage that is fresh tends to cause the grass on the edge of the damaged area to pull up freely from the lawn. If the insect damage is long gone, then fresh grass will no longer pull up easily.

Summer patch disease on tall fescue

Lawn diseases can also cause patterns like this. Unless a sample is sent to a qualified plant pathologist or we have seen the disease many times before it is a shot in the dark as to which disease it might be. From your picture, it is not a disease pattern I recognize as common to all our area.

Since the problem is gone, there is probably no need to apply an insecticide or fungicide. At this point leave the dead grass alone and do not rake it up or you will open the soil surface to invasion by weeds. Around the end of September through mid October rake up the dead grass and broadcast the same seed or nearly the same seed in the dead areas and mulch the surface with top dressing and fertilizer. I hope this helps.