Flixweed

Descurainia sophia

Life Cycle

Annual or winter annual that reproduces by seed.



Emergence

Seedlings emerge mainly in the fall and early spring.



Flowers

Overwintered rosettes begin to flower near the end of May. Flixweed that emerges in spring starts to flower in mid-June. Both growth forms continue to flower through the summer.



Reproduction

Flixweed shatters easily and produces large quantities of seed. Seeds can survive in the soil for more than three years.

Competition

Overwintered rosettes are strong competitors because they grow rapidly in the spring and use valuable spring moisture before fields can be worked. Spring-emerging flixweed seedlings do not compete as well, especially in heavy crop stands. Flixweed can be a severe problem in perennial forage crops grown for seed.

Management Strategy

The winter annual adaptation is the strongest survival mechanism of flixweed. Crucial steps to control flixweed include prevention of seed production and control of fall rosettes.

Control Mechanisms

• Tillage

Summer fallow - Summer fallow alone will not control flixweed because seed remains viable in the soil for many years. Infested land need not be in summer fallow as long as spring and fall tillage is performed and effectively kills the weeds.

Pre-seeding tillage - Tillage before seeding is crucial to control flixweed. Regardless of the crop, shallow tillage before seeding is necessary to destroy any existing seedlings or rosettes.

Post-seeding tillage - Post-seeding tillage should not be necessary if pre-seeding tillage is performed.

Fall tillage - Late fall tillage will control flixweed rosettes that would otherwise overwinter. Take care to leave enough crop residues to protect the land against erosion.


• Rotation
  Flixweed in established winter annual crops cannot be controlled without chemicals. However, any heavily seeded, fertilized annual or perennial crop should compete well against flixweed.
  
  
• Seeding
  Seed crops slightly heavier than normal to encourage competition. Cereals that may require harrowing after emergence should be seeded deeper than normal (7.5 cm).
  
  
• Mowing
  In the year that perennial crops are established, mowing is effective to prevent flixweed seed production, although low growing plants may be missed.