Control of orchard grass in lawns not easy
Orchard grass is prized as a hay source and despised as a weed often found in tall fescue lawns.
"It can make lawns look ragged within 24 hours of mowing," said Ward Upham, horticulturist, Kansas State University Research and Extension.
Like tall fescue, orchard grass is a cool-season bunch grass. It spreads via seeds, not underground plant parts. Once established, it grows in tufts or clumps and performs best in cool weather.
"It's also very visible in tall fescue lawns. Orchard grass is a noticeably lighter green. Plus, it grows so fast that it's soon sticking up above the mowed turf," Upham said.
Bringing orchard grass into a landscape is much easier than getting rid of it, he warned.
"Any tall fescue seed marked as containing a percentage of 'other crop seed' is likely to have orchard grass seeds in it. K-31 seed is almost notorious for that," Upham said. "Orchard grass is listed as a crop, not a weed, because it really is a widely used pasture grass.
"The best line of defense against this 'other crop' is buying good seed--preferably with zero percent contaminants. Once planted, orchard grass has few and painful control options."
He recommends spot-spraying the light-green clumps with glyphosate (Roundup, Killzall Weed and Grass Killer, Kleeraway Systemic Weed and Grass Killer, and others). The remedial steps after that are to wait until the spots turn brown, cut out the clumps and replace them with a small piece of fescue sod.
"You've got to keep the spray spots as small as possible. Glyphosate will kill anything green, including lawns," Upham said. "If the problem's widespread, though, you may find it more practical to kill the lawn this summer and start over with a quality tall fescue in September."