Summer Brown Dead Spots on Lawns

Q. I need your assistance. The photo I sent 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?

Lawn with patches of dead grass; damage is past

and now the grass surrounding the dead spots

is recovering

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. 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 from your picture.

Browning due to poor irrigation coverage
by the sprinklers; darker green near the

sprinklers and brown between; not well defined

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 other than straight lines. I know this might be somewhat boring but water from sprinkler heads tend to be 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 are 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 non turfgrass areas 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 it will no longer pull up.

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.

Distinct horseshoe shape dying spots of summer patch
disease on winter overseeded perennial ryegrass

 

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. Since the cause of the problem is unknown it would be hard to tell you how to prevent it from happening again.

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.