Stinkweed

Thlaspi arvense

Life Cycle

A summer and winter annual that reproduces by seed.

Emergence

Emergence of summer annuals occurs mainly in early spring. Seeds of winter annual germinate in late summer; seedlings overwinter and continue to grow in the spring.

Flowers

Winter annuals can flower in early spring. Flower and seed production of both forms take place throughout the summer.

Reproduction

Stinkweed seed can live for up to six years in the tillage zone. Seeds that are buried deeper than the tillage zone can live for up to 20 years and germinate when the come close to the surface. Dormancy of stinkweed seeds is encouraged by a thick seed coat.

Competition

Stinkweed can compete with crops for moisture and nutrients. However, a well-fertilized crop that has a head start over stinkweed will compete well.

Management Strategy

Control of fall rosettes of winter annuals is important so that seed is not formed early the following spring. During any tillage operations plants with developed pods should not be turned under because they can continue to ripen on the stalks in warm soil.

Control Mechanisms

• Tillage
  Summer fallow - Till early in the spring after stinkweed emerges. Make a shallow tillage in summer if needed. Fall tillage will control the winter annual rosettes.
  
  Pre-seeding tillage - To minimize competition with the crop, control weed seedlings in the spring with a shallow tillage operation before or during the seeding operation. If overwintered stinkweed is a problem, till early in the spring.
  
  Post-seeding tillage - Post-seeding tillage should not be required if pre-seeding tillage is done, or if seeding is after the main spring weed emergence.
  
  Fall tillage - Fall tillage controls rosettes that would otherwise overwinter and stimulates germination of annual weed seeds. Shallow tillage in early October with a field cultivator will conserve some crop residue and destroy weed seedlings.
  
  
• Rotation
  Crop rotation alone will not control stinkweed. A summer fallow year in the rotation will help to reduce seed levels in the soil. Seedlings will still germinate from existing seeds.
  
  
• Seeding
  Seed after the main weed seedling emergence. Waiting for stinkweed to emerge may delay seeding slightly.
  
  
• Mowing
  Mowing prevents seed production but short plants may escape cutting.