Alfalfa seeding needs weed control Planning for successful seeding includes weed control issues, said Leon Wrage, extension weeds specialist at South Dakota State University.
"Perennial weeds should be weakened before planting and annual weeds in the crop can take its toll on the stand," he said.
Wrage said alfalfa is a good crop for reducing Canada thistle but the weeds have to be controlled adequately to allow the alfalfa to get started.
"Roundup works well; it's best to have applied it last fall but spring treatments will set back early perennial growth," he said. "Roundup or Gramoxone can be used to burndown annuals before seeding in no-till."
Wrage also recommends checking last year's herbicides for carryover restriction. Atrazine, Tordon, Ally, Peak and Finesse are some herbicides that require a greater than 12-month interval, he said.
Priority weeds for alfalfa are annual grasses such as green or yellow foxtail, noted Wrage.
"These grasses have taken out over half the stand in our test plots when there is stress," he said.
The specialist said herbicides can be helpful in this situation. Some he mentioned were:
* Eptam or Trifluralin (Treflan) incorporated before planting to control grasses. Trifluralin helps with some small-seeded annuals.
* Pursuit for post-emergence control of many annual broadleaves and help with foxtail.
* Poast, Poast Plus, or Select to control annual grass and volunteer cereals. Select is new for 1999.
* Buctril or Butyrac 200, applied post-emergence, for broadleaf weeds.
"Follow guidelines for rates, crop stage and application-to-harvest intervals," said Wrage. "Check with your product supplier, some herbicides may be more favorably priced this spring."
Complete information is available in FS 525L, Weed Control in Forage Legumes. Copies are available at local County Extension offices.