The scorching temperatures and lack of any significant rainfall have taken a toll on most lawns in upper Midwest landscapes.

Without regular irrigation cycles and uniform coverage, most lawns have turned brown. Any green showing usually is from patches of weeds.

Even those who have watered to keep their grass green have experienced brown spots that can be attributed to one or a combination of the following:

• Heat stress because the temperatures are too high to keep the grass from going dormant
• Grub, sod webworm or other insect activity that has lowered the plant’s ability to utilize the available water
• Patch diseases, which are fungal diseases that develop in the turf when the air and dew point temperature added together are equal to or greater than 150 F (For example, an air temperature of 95 F plus a dew point temperature of 74 F equals 169.)

“If the turf is to be watered, it should be done on a regular basis without any extended days of not watering,” says Ron Smith, North Dakota State University Extension Service horticulturist. “If you choose not to water, then don’t. Too many homeowners will begin to feel guilty and start watering after the grass turns brown but turns the water off when they see the water bill.”

If a dormant turf goes more than 21 days without water from Mother Nature or an irrigation system, the turfgrass should get just one shot of water (about 0.25 inch) for about 30 minutes of run time per location on the lawn.

This will be enough to rehydrate the crown of the plant without stimulating it to begin turning green and keep it alive until the normal rain cycles return.

Dormant turf should not be mowed, Smith says. Turf that is growing should be mowed at 3 inches or higher during the cooler part of the evening.

“A herbicide application will not be effective while weeds are experiencing drought conditions,” Smith says. “Any weed treatments should be delayed until fall when weather conditions are milder and the plants are moving photosynthates into the crown, roots and rhizomes. At that time, a herbicide application will be much more effective.”

With the rainfall some of the region has experienced, most lawns will recover and some even may turn green again.

NDSU Agriculture Communication – July 26, 2012