Bacterial wilt of potato: declared pest

Page last updated: Thursday, 11 July 2019 - 5:12pm

Bacterial wilt (Ralstonia solanacearum) is a serious disease of potatoes that can cause crop losses of more than 90%. This pest is not known to occur in Western Australia. Early detection and reporting of bacterial wilt will help protect the Western Australian potato industry.

Plants affected 

The main host of bacterial wilt is potato, but the disease can also affect tomato, eggplant, geranium (Pelargonium) and the weed blackberry nightshade (Solanum nigrum).

What to look for 

  • Bacterial wilt of potatoes appears as sudden wilting of one or more stems of the potato plant. This symptom can be mistaken for water stress. Plants may also look stunted and begin to yellow.
  • Brown discolouration is visible in the vascular tissues of the stem and tubers. When stems or tubers are cut and slight pressure applied, creamy bacterial slime comes from the infected vascular elements.
  • Bacterial slime oozes from the eyes of tubers and soil sticks to the tubers where the slime has emerged.
  • Secondary infection can cause decay of the whole tuber.
  • External symptoms and internal browning are not always visible in infected plants, and potato tubers can be infected without any visible symptoms.

Survival and spread

  • New outbreaks of bacterial wilt are most often caused when infected potato tubers that appear healthy are planted.
  • The disease can also spread in contaminated soil carried on boots, tools and cultivation equipment and contaminated irrigation or flood water.
  • Weed hosts on the side of rivers and streams can carry the bacterial wilt pathogen.  
  • The disease can survive up to four years in the soil and in plant debris
  • Bacterial wilt is generally favoured by high soil moisture and low temperatures.
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Bacterial slime oozes from the eyes of tubers and soil sticks to the tubers where the slime has emerged (Andrew Taylor).

Damage

Bacterial wilt can cause total loss of potato crops and prevent the use of land for potato production for several years. It also causes tomato plants to wilt with a reduction of yield and quality.

Status in Western Australia 

Ralstonia solanacearum (Smith 1896) Yabuuchi et al., 1995 is considered 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 is supported by general and specific surveillance (including potato seed certification), specific import requirements to prevent its entry, and legal requirements to report any occurrences of the pest.

Report

It is important that any suspect disease occurrence is reported. Early detection and eradication will help protect Western Australian potato growers. Please make a report using MyPestGuide or contact the Pest and Disease Information Service (PaDIS) to report this pest.

Report your observations using the MyPestGuide Reporter app or online at mypestguide.agric.wa.gov.au.

Contact information

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