Bacterial wilt of lucerne: declared pest

Page last updated: Thursday, 27 October 2022 - 1:20pm

Please note: This content may be out of date and is currently under review.

Bacterial wilt of lucerne (Clavibacter insidiosus) is a disease that reduces the lifespan and productivity of lucerne stands. It also makes lucerne crops hard to establish. This disease does not occur in Western Australia. Early detection and reporting of bacterial wilt of lucerne will help protect the Western Australian agriculture industry.

What plants are affected? 

The main host of the disease is lucerne (Medicago sativa). Lucerne is a fodder crop which is also known as alfalfa.

What do I look for?

  • Infected plants are stunted and yellowed.
  • Leaves are small and often have dried edges.
  • Dark discolouration can be seen when roots are cut open.
  • Plants can die suddenly, particularly in hot weather.

How does the pest survive and spread?

  • Bacterial wilt survives in lucerne plant material for up to 10 years and in the soil.
  • The greatest risk of spread is by planting infected seed.
  • The disease can also be spread by contaminated farm machinery, animals, lucerne hay and water if these are introduced to land where lucerne is grown.

What damage can this pest cause?

Bacterial wilt reduces lucerne yield and the length of stand survival. The use of lucerne to lower the water table in areas threatened by salinity would be threatened if bacterial wilt of lucerne became established in Western Australia.

Status in Western Australia 

Clavibacter insidiosus (McCulloch 1925) Li et al. 2018 is absent from Western Australia and is a quarantine pest.

It is a prohibited organism under section 12 of the Biosecurity and Agriculture Management Act 2007.

Western Australia's Pest Freedom for Bacterial wilt of lucerne is supported by general and specific surveillance, and specific import requirements to prevent its entry. A person who finds or suspects the presence of Bacterial wilt of lucerne must report it to DPIRD.

Report suspect disease 

Early detection and eradication will help protect Western Australian agriculture. Please make a report on MyPestGuide Reporter to report this pest.

Report your observations using the MyPestGuide Reporter app or online at

Contact information

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080