North-central South Dakota hayfields may have more problems with leafy spurge this year than in the past, according to a South Dakota State University Extension specialist.

“Since these new patches are developing, landowners need to scout their pastures, hay lands, ditches and shelterbelts for this aggressive noxious weed,” says Mark Rosenberg, SDSU Extension agronomist and weed specialist.

Leafy spurge, a noxious plant, infests 309,420 acres of land in the state, according to the South Dakota Department of Agriculture. It’s a hard-to-control creeping perennial with long, narrow, dark-green leaves and stems that reach 2-3’ tall. The plant contains milky sap and small green flowers surrounded by yellow-green bracts. Its roots can reach 20’ deep.

“Management programs typically require several years and can be very costly. Therefore, it is strongly recommended to watch for new patches and control infestations while they are small,” Rosenberg says.

Standard herbicide programs include the use of Tordon (spot treatment rate at 1-2 qt), Tordon (1.5 pt) + 2,4-D ester (1 lb active ingredient), or Plateau (8-12 oz). All rates are per acre.

Apply herbicide early in June at flowering or wait until regrowth in September or October or while the white sap is still flowing, he adds. Plateau may be used around some tree species, but landowners should first read and follow label precautions.

Perspective, at a 4.75- 8 oz/acre rate, is also labeled for control of the weed but cannot be applied to grass that will be grazed or hayed, Rosenberg warns.

Landowners with large infestations or sensitive areas should consider introducing bio-control agents such as leafy spurge flea beetles, he says.

Learn more at iGrow.org. For information on bio-control options, call Darrell Deneke at SDSU at 605-688-4595, Rosenberg at 605-626-2870 or the South Dakota Department of Agriculture at 605-773-5425.