Taun Beddes: Reasons why your lawn is suddenly turning brown
May 25, 2024, 2:00 PM | Updated: May 27, 2024, 11:36 pm
The KSL Greenhouse show host Taun Beddes shares why lawns might turn brown and how to treat those lawns. (Canva)
(Canva)
SALT LAKE CITY — A few years ago, during my first spring with the Utah State University Extension, I received numerous calls about lawns suddenly turning brown after being beautifully green.
It was late May, and most callers believed they had a serious lawn disease that had struck overnight. However, I knew that lawn diseases do not spread so quickly; entire cities do not become infested overnight.
When such events occur, environmental factors are usually the cause. In this case, Utah had experienced a sudden transition from 60 to 70-degree temperatures to the low 90s.
A normal response to drought stress
It had not rained for several days, and lawns lacked the soil moisture to cope with the hot weather. As a result, lawns began to go dormant, turning brown in large patches, although the crowns and roots remained alive. This is a normal response to drought stress.
Many people’s first reaction is to overwater the lawn, thinking it will break dormancy faster. However, excessive irrigation can harm the lawn in the long term. The better approach is to water normally.
If caught soon enough, the lawn will recover and turn green over a few weeks. If the lawn is not watered soon enough, it may enter hard dormancy, which can take several weeks to reverse.
Is it stressed or is it grubs?
In mid to late spring, a common mistake is confusing grub or sod webworm damage with drought stress. I conduct simple tests to diagnose the issue.
The first test involves poking a screwdriver with a 6-inch shaft into the soil where the grass is brown up to the hilt. If it slides in easily, the soil is sufficiently moist, and irrigation is not the problem.
The next step is to pull the grass from the edges of the brown spot. If it pulls up easily, indicating that something has eaten the roots and crowns, then lawn-feeding insects are likely the cause.
Next, you need to determine whether the damage is from various species of beetle grubs or sod webworms. If they are sod webworms, small white moths will fly up as you walk through the lawn.
Sod webworms are easier to control, and a product can be applied to the lawn at any time during the growing season.
Grubs can be much harder to manage. If caught in late May or early June, a preventative measure can suppress further damage. And if their damage is not caught until July, treating it is often too late.
And finally, fungus
If brown grass doesn’t pull out easily and neither irrigation issues nor lawn-feeding insects are the problem, it may be a lawn fungus. In this case, it’s a good idea to send a sample to the Utah State University’s Extension Pest Lab for further diagnosis.
The cost for the lab work varies from $10 to $20. For more information about lawn pests, you can search online for “USU Extension sod webworm” or “lawn grubs.”
