Potato Spindle Tuber Viroid (PSTVd)
It is particularly destructive for seed production. Potato plants severely infected are upright, stunted and much thinner than normal plants. Leaves of infected plants are smaller and may be grey or distorted. The affected stems are often more branched and branches are at very sharp angles to the stem. Symptoms are more obvious on tubers. Affected tubers are small, narrow and spindle shaped (oblong).
In some varieties tubers develop knobs and swellings. In other varieties eyes on tubers are numerous, shallow and prominent, and affected tubers are often cracked. This viroid is easily mechanically transmitted. An infection can be introduced by sowing infected seed tubers, by insects such as aphids, grasshoppers and flea beetles, and through pollen. Tomato and capsicum are additional hosts for PSTVd.
- Plant certified disease-free seed tubers.
- Plant whole seed tubers instead of cut pieces.
- Remove infected plants from the field.
