Cover Crops: Other Brassicas

Table of Contents

  1. Description: Family
  2. Growth Habits
  3. Control Options
  4. Sensitivity to Herbicides
  5. Weed Control
  6. Benefits and Concerns
  7. Getting Started
  8. Related Links



  • Brassicae, Non-legume broadleaf, includes canola – spring and winter, rapeseed , mustard – black and white

Growth Habits


  • some seeds that may not germinate the first year may pose a problem in later years

Top Growth

  • prefers moist, cool growing conditions
  • rapid top growth and dense cover
  • Some may bolt by October, set seed and pose a future weed problem

Root System

  • most have taproots, 0.3 to 1 m long
  • root growth is aggressive with many side roots


  • tolerant of light frost
  • spring canola and mustards are resistant to mild freezing – but less so than oilseed radish; -2°C kills mustard
  • winter canola and rapeseed will over winter as rosettes

Site suitability

  • tolerates dry conditions, once established
  • loam to clay soils preferred
  • pH range 5.3 to 6.8

Control Options

  • several herbicides are registered for brassicas

Sensitivity to Herbicides

  • Many of the Group 2 herbicides, and the triazine herbicides, can have soil residuals that may injure oilseed radish seedlings.
  • Consult the product labels or Publication 75 - Guide to Weed Control for information on how these herbicides may affect canola, cabbage or other members of the mustard (cruciferae) family of plants.

Weed Control

  • One method of controlling volunteer cereals and other annual weeds is to disc or cultivate immediately after harvest and then till the soil again just before seeding the cover crop (stale seedbed).
  • do not delay the date of seeding, a vigorous and competitive cover crop is your best weed control.
  • There is a certain percentage of hard seed that may not germinate in the year of planting and may pose a weed problem in later years.

Benefits and Concerns

Nutrient Management

  • Good nitrogen scavenger –a good fit with fall manure applications or when excess soil nitrogen is expected

Pest Management

  • Some varieties have nematode suppressing abilities due to high glucosinolate levels
  • Clubroot disease and cabbage root maggot can affect many of these types of cover crop. Avoid using these cover crops in a rotation that includes brassicas in the main crop.

Organic Matter

  • biomass production varies greatly with species and growing conditions
  • Residues have low lignin content – rapid decomposition
  • Returns moderate amounts of organic matter to the soil

Erosion Control

  • rapid growth for weed suppression and soil cover in early fall and spring

Getting Started


  • seed in early spring or fall – depending on species
  • most seeds are quite small
  • drill at 10-12 lbs per acre or broadcast at 12-15 lbs/acre
  • do not delay seeding date – competitive crop cover is best weed control strategy

Cost and Availability

  • moderate cost depending upon the variety

Related Links

For more information:
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