Potato spindle tuber viroid
Potato spindle tuber viroid (PSTVd) can reduce the yields of potato by 65% and tomatoes 40 to 50%.
PSTVd has been reported around the world, including in Australia. In Victoria, it was detected only in tomatoes and then eradicated.
A viroid is like a virus but has a simpler structure.
Symptoms of PSTVd
In potato, infection with PSTVd often causes smaller and elongated potatoes. While above the ground, the potato plant can become usually upright and extended with smaller leaves.
In tomato plants, symptoms can include stunting and discolouration of the leaves that initially turn yellow and then become red or purple (Figure 1). Tomato fruit production also stops with severe infections.
Management of PSTVd
The best way to avoid disease is by using planting material free of PSTVd. For example:
- only get seed potatoes from suppliers with tubers certified free of PSTVd
- source tomato seeds from a reliable supplier
PSTVd can be found in the sap of plants and is easily spread by contact. Appropriate sanitisation and precautions are needed to prevent the transmission of PSTVd by machinery, tools and people that have been in contact with infected plants.
A consideration during an incursion, is that other plants can be a reservoir and sources of PSTVd. These include
- weeds such as Brugmansia suaveolens (white angel's trumpet) and Solanum nigrum (black nightshade)
- commercially important plants such as Capsicum annuum (capsicum), Solanum melongena (eggplant) and Persea americana (avocado)
Those in the latter group are often not as badly affected as potato by PSTVd. These hosts can be symptomless.
Figure 1 courtesy of the Department of Agriculture and Food, Western Australia.
CABI, 2020. Potato spindle tuber viroid (spindle tuber of potato). In: Invasive Species Compendium. Wallingford, UK: CAB International. www.cabi.org/isc.
Plant Health Australia, 2015. Fact sheet: potato spindle tuber viroid [Web page], retrieved from https://www.planthealthaustralia.com.au/wp-content/uploads/2015/08/Potato-spindle-tuber-viroid-FS.pdf on 13 May 2020.