Does your lawn look like a Dalmatian?  Spots of dead and live turf here and there?  More here than there?  If so, here are some possible causes at this time of year:

*Summer Patch – this fungus disease infects turfgrass in late April, then grows inside the crown and roots of the plant, later causing them to rot.  In the heat of summer, because the roots are not able to pull water out of the soil, the plants wilt and die.  In most cases, the damage takes on the form of round to half-moon shaped spots.  Once you see the damage, not much can be done, except to reseed/re-sod.  In the following spring, preventative Banner fungicide treatments can also provide some relief.

*Dog Spots – roundish spots that have been killed by drops of dog wastes show up at most times of the year, but are usually most evident in the warmer months.  Rotation of dog exercise locations, frequent dilution, waste removal and reseeding are the pertinent steps to take.

*Herbicide Injury – whether from applications made in temperatures above 90 degrees F or being sprayed by mistake i.e. Roundup, not Trimec, spots of dead grass are certainly evident this time of year.  Checking on the history of the application and weather specifics are keys to determining the cause.

*Inconsistent Watering – uneven watering is a common cause of dead spots in the lawn.  When turf is watered non-uniformly, the roots die in a similar fashion to summer patch, but from drying out, not rotting.  Either way, the result and repair is the same, except for fungicide application the following spring.

*Thinning Caused by Shade – turfgrass is generally considered to be a sun plant, requiring 6-8 hours for Kentucky bluegrass and 4 for tall fescue.  In sites that receive 3 or less, the common response is a gradually thinning, sometimes appearing as dead spots.  The best landscape correction is to utilize the principle of right plant, right place and install shady groundcovers or perennials instead of turfgrass.

John Fech

Horticulture Extension Educator at Nebraska Extension

John Fech is a horticulturist with the University of Nebraska-Lincoln and certified arborist with the International Society of Arboriculture. The author of 2 books and over 200 popular and trade journal articles, he focuses his time on teaching effective landscape maintenance techniques, water conservation, diagnosing turf and ornamental problems and encouraging effective bilingual communication in the green industry. He works extensively with the media to extend the message of landscape sustainability, making over 100 television and radio appearances each year.