Potato spindle tuber viroid is a serious plant disease that affects the growth of plants, mainly tomatoes, potatoes, ornamentals and solanaceous weeds. PSTVd is generally symptomless in ornamentals and weeds.
Use certified disease-free planting material, destroy infected plant material, and employ on-farm biosecurity practices to prevent unwanted diseases, pests and weeds from entering your property. By doing so, you will also protect Western Australia's agricultural industries.
PSTVd was first reported as a disease in potatoes in North America and first detected on tomatoes in South Africa. The disease is reported to occur in Asia, Africa, North America, South America, and Europe.
There have been previous detections and eradications of PSTVd in Australia, including in Western Australia.
Agricultural and economic impact
Yield and quality losses
The yield of marketable potatoes and tomatoes from affected plants can be significantly reduced, but varies with plant age, age when infected and disease severity. There have been reports of yield losses in potatoes of up to 65% and of 10–60% in tomatoes due to PSTVd.
Various changes in growth habit and to foliage, roots, flowers, and fruit occur in plants infected with PSTVd.
Symptoms may be confused with those of nutrient imbalance, spray damage, insect damage or other plant diseases such as true viruses.
Some infected plants may have no visible symptoms. The severity of symptoms can vary due to different strains of the viroid.
Foliage symptoms are often difficult to recognise and are rarely distinguishable before maturing.
(L) infected potato tubers; (R) healthy potato
Foliage and tuber symptoms become more severe with each generation.
(L) Infected tomato plant; (R) healthy plant
Disease transmission occurs between plants through contact of the sap from small wounds in the leaf of a diseased plant to a healthy plant.
Initial introduction of the viroid into potato and tomato crops is mostly through infected seed.
Spread can occur through
- handling of plants
- movement of animals and machinery through a crop
- cutting tools
Transmission also occurs through pollen but only to the seeds pollinated, not to the whole plant. Transmission is also reported by aphids if the source plant is also infected with Potato leafroll virus.
Prevention and control
There are no products to prevent or treat PSTVd infection.
Control is achieved through strict biosecurity measures, including the appropriate destruction of infected plant material and the sanitation of tools and production facilities.
To prevent infections:
- Use healthy planting material.
- When planting potatoes use certified seed potatoes.
To reduce spread within a crop:
Limit the movement of machinery, vehicles and people:
- between infected areas and uninfected areas.
- entering production areas.
- Clean machinery, vehicles and equipment after any contact with an infected area and between paddocks.
- Wash cutting tools in a solution of 2% sodium hypochlorite after use.
- Change or sterilise clothes and shoes when moving from areas where PSTVd is present into clean areas.
- Wear vinyl or latex gloves when handling infected plants and change gloves regularly.
- Always work in clean areas first and then move to infected areas.
- Remove crop plants infected with PSTVd, and those nearby that could be recently infected. Deep bury or burn them rather than cultivated back into the soil after harvest.
- Control weeds and volunteer plants that can be sources of infection.
Status in Western Australia
Potato spindle tuber viroid is a prohibited organism under section 12 of the Biosecurity and Agriculture Management Act 2007.
Western Australia's Regional Pest Freedom for PSTVd is supported by general and specific surveillance. A person who finds or suspects the presence of PSTVd must report it to DPIRD.
Report suspect disease
Early detection and eradication will help protect Western Australian tomato and potato growers. Please make a report on MyPestGuide or contact the Pest and Disease Information Service (PaDIS).
Samples of suspected PSTVd infected leaves or tubers can be sent for testing to DDLS-Plant Pathology. Complete the Potato virus identification form clearly marking the ‘Potato spindle tuber viroid PCR test’ and writing ‘suspect potato spindle tuber viroid’ in the comments section.