How is PSTVd transmitted?

Viroids are easily transmitted by touching infected plants, by cuttings, by infected tools used for cutting, but not so easily with seed, pollen and aphids. Transmission of the viroid PSTVd from infected on healthy plants is easy therefore a special danger is posed by introduction into greenhouses, where tomato and eggplants are cultivated, as well as close to potato-growing surfaces. Since also weeds of the family Solanaceae are subject of infection, fast spread from infected plants is very likely.