Basic Principles of Integrated Weed Management (IWM)

Basic Principles of Integrated Weed Management (IWM)

• Suppression of weed growth
• Prevention/suppression of weed seed production
• Reduction of seed bank (weed reserves in the soil)
• Prevention/reduction of weed spread

Weed PREVENTION strategies:

• Use certified seed
• Keep weeding implements clean
• Control weeds prior to seed set
• If using manure, make sure it is well rotted

Physical weed CONTROL strategies:

• Tillage – spring tillage destroys the first flush of weeds; fall tillage can effectively destroy biennials and suppress perennial weed growth
  • Annual weeds: tillage prevents seed set
  • Perennial weeds: tillage destroys roots
    • Tillage destroys weeds by:
      • Burying the plant
      • Depleting food reserves
      • Exposing roots to desiccation and frost
      • Encouraging rotting of roots
    • Hand weeding – effective for annual, biennial and non creeping perennial weeds
    • Mowing – depletes food reserves in the roots of perennial weeds; mowing is most effective just prior to bloom in perennial weeds when food reserves in the roots are at their lowest level
    • Mulching – excludes light causing depletion of food reserves in the roots
    • Torch weeds - use extreme caution
    • Pour boiling water on weeds - use extreme caution

Cultural weed CONTROL strategies:

• • Plant competition – weeds compete with desired plants for light, soil moisture, soil nutrients, carbon dioxide and space; weeds are strong competitors by nature
    • Early weed control is exceptionally important to prevent further build up of the weed seed bank
  • Crop establishment – usually the first plants to germinate and emerge tend to exclude all other plants from the area; ensure successful germination of your crop by using certified seed and supplying the crop with adequate water and nutrition

  Adapted from Integrated Weed Management; British Columbia Ministry of Agriculture and Land