Kansas Ag Connection - Central U.S. Lawn Grasses Struggling

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Central U.S. Lawn Grasses Struggling
Kansas Ag Connection - 07/30/2010

Turf specialist Rodney St. John has been worrying since June about the survival odds this year for central U.S. park, lawn, playing field, and putting green grasses.

"The basic problem is that the ground stayed soaking wet for most of spring and into the summer. Plus, we had periods of significant heat, combined with high humidity," said St. John, who's with Kansas State University Research and Extension.

Ironically, many lawns also experienced two periods of drought stress, he added. From late March into early April, for example, Kansas was under a red flag warning (highest wildfire risk). But, about the only people who noticed were ranchers needing to burn pastures.

The precipitation records don't suggest turf areas faced more droughty conditions in June. Many of the region's weather stations set a new monthly high for total June rainfall. Dodge City in southwest Kansas received 147 percent of its normal June precipitation, while Topeka in the northeast received 195 percent.

"It was too much of a good thing," St. John said. "To do their job, all plant roots need oxygen. But, waterlogged soils no longer have room for tiny pockets of air. So, if roots stay soaking wet too long, they start to 'drown' - from the bottom up. Lawns struggle and may even die."

This was the cause of late June's drought-type stress for lawns.

"By mid-June, excessive soil moisture had already shortened the roots of tall fescue and Kentucky bluegrass. Then, the weather turned hot and dry," St. John explained. "Those lawn grasses didn't have enough of a root system to keep themselves cool, much less maintain an adequate water supply for the plant. When the top soil dried out, those roots also couldn't reach to get moisture from deeper down."

Unfortunately, insects and diseases like to attack weak and damaged plants, the turf specialist added. Moreover, most plant diseases thrive in warm, moist conditions, so this spring they were "going crazy." The resulting damage, in turn, gave lawn weeds more room to settle in.

"When heat and/or drought set in, lawns may need more frequent watering to avoid damage or death this summer," St. John said. "In years of more average rainfall, K-State's typical advice helps head off the problems we're facing now: Water deeply and infrequently, encouraging turf to develop deep roots. And, let the surface dry slightly between waterings, allowing air to move deeper into the soil."