Telling the Difference Between Drought Stress and Grub Damage in Lawns
Many years ago I had the chance to manage a seven acre landscape of a high profile client. Prior to this opportunity the only experience I had in lawn care was mowing my grandmother’s lawn once a week, a job which was simple enough for any teen-aged boy to handle. The client I worked for expected nothing less than the best and had absolutely no tolerance for dingy lawns, algae infested ponds, or the slightest leaf or flower out of place. And I was the only poor soul that managed those seven acres of lush, green hell. It took me two and half days to mow and trim the lawn alone, nevermind maintenance of the orchards, pool, tennis courts, perennial and annual beds, and horse pasture. Needless to say, that was one of the most stressful jobs I’ve ever had the privilege of working. I learned in the two years I worked there more about the proper care and maintenance of lawn grass than I’d learned my whole life prior to that experience.
Summer Heat or Pest Related?
During the peak of the summer months, it is not uncommon for our Kentucky bluegrass seed dominated lawns to start to look a bit dingy or scruffy. This is to be expected of a cool-season grass trying to deal with the extreme temperatures of summer. The bluegrass wants to go dormant; the natural defense the grass uses to avoid death during drought. Many times during my job as property manager I had to figure out why the grass was yellow or browning in certain areas. Was it not getting enough water? Was it pest related? Did someone park their four-wheeler on the lawn again and leak gasoline all over? Was it too shady? The possibilities were endless.
I soon learned a quick way to diagnose the problem and start eliminating the possible reasons.
How to Identify the Problem
Walk over to the brown or dingy spot in your lawn. Kneel down and try to pull the grass out by the roots with your hands. Is it hard to pull out? If the grass is hard to pull out, requiring a decent amount of force, it is not grub damage and is most likely not getting enough water. You can also use a screwdriver to see if the brown patch is under-irrigated. Push a screwdriver into the suspect grass. If it is hard to push, or won’t even penetrate the soil surface, the grass is definitely not getting enough water. But if the screwdriver penetrates the soil easily and smoothly, irrigation is adequate. If when you try to pull the grass out by the roots the grass just pulls up with no resistance, there is a good chance you have a grub infestation. Grubs eat the roots of the grass. You will notice as you pull up the grass there are no roots, or that the roots are barely attached to the grass. This is a classic sign of grub damage.
There are other pests and problems that could be causing a brown patch in your lawn. But by running these two simple tests you can either eliminate or identify some of the most common summertime lawn problems in Kentucky bluegrass.