Don’t blame the bugs for dry spots in your lawn
Every time we have an extended dry period in spring or summer, I get those predictable calls about some mysterious pest that’s playing havoc in lawns. In most cases, I believe the people calling could answer their own question without me saying a single word if they’d carefully listen to their own description.
The typical call concerning these “mysterious lawn pests” will have certain common features. First, they only occur during dry weather. Second, the caller usually has an automatic sprinkler system. Third, the caller has been unsuccessful in finding and/or controlling the unseen pest.
I prefer getting these calls before any control measures have been attempted. I’ll explain why later. The caller describes areas in their lawn that turn yellow and then brown. Without realizing it, they usually do an excellent job describing a textbook example of dry spots in a lawn. And that is exactly what the problem areas are – dry spots.
These dry spots are the result of imperfections in an irrigation system . And they are revealed during extended dry weather. During times of adequate rainfall, the rain masks the imperfections in an irrigation system. This is a very common problem. There are many imperfect sprinkler systems out there.
The possible imperfections are many. The homeowner may easily fix some irrigation system problems while other may require the expertise of a properly licensed irrigation contractor. There may be too few sprinkler heads for adequate coverage, insufficient pressure to operate each zone, not enough zones, incorrect choice of nozzles, wrongly mixing rotors with spray heads on the same zone or the use of spray heads with unmatched precipitation rates. The cause for the dry spots may be as simple as a maladjusted spray head, a broken spray head, a plugged nozzle, a tree trunk or tall shrub blocking the water, grass that has grown over a pop-up spray head, etc.
Regardless of the cause, there are a couple of simple tests that can help confirm that the problem areas are to be blamed on the lack of sufficient water vs. some mysterious pest.
First, check the affected areas by taking a soil sample in the root zone. You can use a soil probe or a shovel. Take out a core of soil to a depth of 6 to 8 inches. Visually inspect and feel the soil in the root area for moisture. Then do the same in an adjacent area of the lawn that looks normal and compare the difference. It should be obvious if there is an appreciable difference in moisture between the areas tested.
The second test involves placing several empty straight-sided cans (such as soup or tuna fish cans) in the affected area and several in a “normal” area of the lawn. Then cut on the irrigation system and let it run long enough to collect some water in the cans. Compare the amount of water collected in the two areas. Again, it should be obvious if there is an appreciable difference in the amount of water applied in the areas tested.
The reason I prefer to get the call concerning these dry spots before someone experiments with controlling these mystery pests should now be obvious. The above two tests are much cheaper, less trouble and more environmentally friendly as compared to purchasing and applying pesticides for nonexistent pests. Many people will treat for mole crickets, a disease or other lawn pest as a result of incorrectly diagnosing the problem. Finally, it may help to occasionally inspect your irrigation system while it’s running for any obvious, easily corrected problems such as a maladjusted or broken spray head. If these tests do not identify the cause for the problem as lack of water, you may have a lawn pest. But don’t guess.
If you’re not sure about your diagnosis, contact a reputable lawn care or pest control business or your local University of Florida Extension Office. Larry Williams is the extension horticulture agent with the Okaloosa County Cooperative Extension Service, University of Florida.