Diagnosing clubroot in canola

Clubroot is caused by a soil-borne fungus that only affects plants in the Cruciferae family including canola,mustard, wild radish, wild mustard, wild turnip and vegetable brassicas. This is a serious disease but damage in WA is presently mild and infrequent.

Group I herbicide damage can also cause root nodules
Mild clubroot infection
Severe clubroot infection

What to look for

    Paddock

  • Wilted stunted plants with yellowing leaves

    Plant

  • Roots of affected plants become malformed and show galls that may be either spherical or spindle shaped.
  • The galls are at first firm and white but become soft and greyish brown as they mature and decay.
  • Restricted water and nutrient availability leads to stunted plants that wilt readily, may appear nutrient deficient and ripen prematurely

Where did it come from?

Contaminated soil
Contaminated soil
  • Resting spores of the fungus can survive in soil for many years, even in the absence of a susceptible host.
  • Paddocks mainly become infected by the movement of soil on cultivation equipment Infection can occur at any stage of growth and is restricted to the roots.
  • In the presence of susceptible roots, resting spores germinate and release tiny motile spores that swim in free water to the surface of the rootlets, penetrate and form a fungal colony inside the root cells.
  • Infected cells enlarge and divide rapidly, resulting in the galls.
  • Late in the season, resting spores develop in the infected roots and are released into the soil as the galls decay.

Management strategies

  • Fungicides are ineffective. In the Australian vegetable brassica industry several methods of control have been developed that may be useful for oilseed brassicas.
  • Five year rotation: Infested paddocks are kept free of susceptible crops and weeds for at least 5 years, to allow sufficient natural decay of the long-lived spores.
  • Equipment movement: Do not move cultivating equipment from infested to non- infested areas before thoroughly cleaning the equipment.
  • Liming: Clubroot thrives in acid soils.Liming to increase soil pH (6.5 to 7 in calcium chloride) has been successful for vegetable brassicas but would be cost prohibitive in most canola areas.
Source URL: https://www.agric.wa.gov.au/mycrop/diagnosing-clubroot-canola
This print version was generated at 2:49pm on the 16th of April, 2024.
The original document was last revised at Thu, 16/04/2015 - 1:18pm

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Important disclaimer

The Chief Executive Officer of the Department of Primary Industries and Regional Development and the State of Western Australia accept no liability whatsoever by reason of negligence or otherwise arising from the use or release of this information or any part of it.