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Faba Bean Weed Control

Good weed control is essential for optimum faba bean production. Faba bean is a poor competitor with weeds especially in the seedling stage – in research plots, faba bean seed yield was reduced by as much as 85 per cent when wild oat levels were high.

Cultural Weed Control

Cultural weed control can be quite variable depending on environmental conditions and stage of weed growth. Cultural weed control should include:

  • appropriate tillage weed control in previous year
  • careful selection of a clean seedbed
  • inclusion of a shallow tillage operation in problem areas prior to seeding
  • use of clean seed
  • a pre-emergent harrow operation if required
  • harrowing during emergence should be avoided due to excessive damage of the seedlings
  • post-emergent harrowing can occur once faba bean seedlings are 2 to 6 in. (5 to 15 cm) high
  • tine harrows are most effective when used crosswise to the direction of seeding and at a ground speed of 6 kmph (4 mph) or less
  • harrowing can increase the risk and spread of disease
  • harrow on a dry, sunny day when plants are somewhat wilted
  • delayed seeding should be avoided as it greatly reduces faba bean yields due to late maturity

Chemical Weed Control

  • begin weed control in the previous crop with a pre-harvest glyphosate treatment (Roundup® or Touchdown®)
  • an application of glyphosate before the seed emerges will also help to control many winter annuals and very early emerging weeds
  • fall application of pre-emergent, soil incorporated herbicides is recommended:
    • provides a more uniform distribution of herbicide for improved weed control and crop tolerance
    • conserves soil moisture by reducing spring tillage operations
    • allows for earlier seeding in most years
  • granular formulations are recommended for fall application into stubble; liquid formulations may be bound by the crop residues, resulting in poorer weed control
  • apply post-emergence herbicides before the crop reaches 20 cm (8 in.)
  • weeds tend to be more susceptible (and fababean more tolerant) at the early growth stages
  • several herbicides are registered for use on fababean to control most of the common weed problems
  • registered as pre-emergent herbicides: Treflan®, Bonanza 400®, Advance 10G®, Rival® (trifluralin), Edge® (ethalfluralin), Lexone® (metribuzin) and trifluralin, Sencor® (metribuzin) and trifluralin or Edge®
  • registered as post-emergent herbicides: Basagran® (bentazon), Hoe-Grass 284® (diclofop-methyl) and Poast Ultra® (sethoxydim)
  • For detailed information on applying these herbicides and what weeds they will control, consult Agdex 606-1, Crop Protection.