Narrow-Leaved Hawk's Beard

Crepis tectorum

Life Cycle

An annual or winter annual that reproduces by seeds.

Emergence

Main flushes emerge from mid-May to mid-June and from early August to mid-September. The first flush develops as annuals and the second develops as winter annuals. Sporadic emergence occurs at other times.

Flowers

Annuals flower from early July through August. Winter annuals flower the year after emergence between mid-June and mid-July.

Reproduction

Seeds of winter annuals are set from mid-July to mid-August. Seeds from annuals mature from early August through fall. Seeds exhibit little or no dormancy, losing their ability to germinate after about five years.

Competition

Narrow-leaved hawk's-beard is a serious weed of perennial forages. The winter annual form competes with established forages; the annual form competes with seedling forages, special crops, cereals and oilseeds. The most serious infestations of this weed occur in weak crop stands.

Management Strategy

Prevent seed production and encourage strong crop stands.

Control Mechanisms

• Tillage
  Summer fallow - Summer fallow reduces populations of narrow-leaved hawk's-beard. However, plants can easily re-root after tillage, especially in wet conditions. Consequently, tillage should be done during hot, dry weather. Perform tillage after the main flushes of annuals appear and in the fall to destroy rosettes of winter annual.

  Pre-seeding tillage - Early, thorough spring tillage destroys weeds that have overwintered. Annual crops can then be seeded. Do not seed perennial crops until the first flush of seedlings has been destroyed by cultivation.

  Fall tillage - Cultivate thoroughly after weed emergence is complete in the fall, usually around mid-September. If possible, conditions should be dry so that the rosettes do not re-root.

• Rotation
  Maintain strong stands of perennial crops for three to four years to discourage weed growth. If perennial crops become infested with narrow-leaved hawk's-beard, work the stand under and summer fallow until the following year.

  Annual crops in the rotation should be well-fertilized and seeded slightly heavier than normal to encourage competition against spring weeds.

  Summer fallow can be an effective control for narrow-leaved hawk's-beard. Perform a shallow tillage after emergence of weeds in the spring and fall and as required during the season.

• Seeding
  Seed annual crops at a heavier than normal rate after the spring flush of narrow-leaved hawk's-beard. Seed perennial crops after weeds have been destroyed by tillage in the spring. Seed fall crops after the fall flush of weed seedlings has been tilled.
  
  
• Mowing
  Mow narrow-leaved hawk's-beard in perennial crops prior to weed seed production. This is especially important in the year that perennial crops are established.