How to recognise infection with PSTVd?

Dutch and Belgian scientists did not find any symptoms on any of infected ornamental plants (Brugmansia cordata, Brugmansia suavolens, Solanum jasminoides), thus plants may be infected in spite of their normal growth and development during the year. 

Infection of ornamental plants of the family Solanaceae is hidden and usually not detected, however it may be extremely harmful for potato and tomato plants, where it is indicated by deformation of tubers and plants, resulting in yields of less than one half of the expected. 

Symptoms are the most characteristic on potato tubers. These are small and deformed: spindle-shaped, more oblong or more round than not infected. They are usually pointed and may be gnarled. Bigger tubers may be cracked. Eyes are usually more expressed and slower in starting to grow. Upper part of the infected potato plant is stunted and more erect and usually more branched than that of a healthy plant, angles between lateral shoots and the stem are acute. Leaves may change their colour to brighter or darker than normal, and may be smaller and deformed.

Infected tomato plants are stunted, with the top in the form of tussocks. Also spindle-shaped shoots may sometimes occur. Leaves become yellow or red, are deformed and curl downwards. Lower and middle leaves die out, starting on leave veins. Younger leaves on top of plants do not decay but stay small. Flowers usually fall off. Ripening of fruits is irregular, fruits are small, solid and often dark green.

Symptoms vary in relation to the type of infecting viroid (mild or strong).