Worldwide distribution. On sweetpotato and wild relatives. Several strains. An important virus disease.
Occurs either alone or with other viruses.
Difficult to identify on symptoms alone. Symptoms variable: yellow or purple spots, or purple bordering veins, sometimes only on a few leaves before recovery. One strain causes cracks around storage roots.
Spread by aphids. Spread is fast: aphids pick up the virus from diseased leaves and can straight away pass it to healthy leaves next time they feed. Ability to spread virus quickly lost.
Cultural control: difficult – symptoms unclear; use pathogen-tested planting material (see SPC CePaCT); avoid planting near older crop; weed.
Chemical control: none recommended. Impractical to control aphids using insecticides to prevent spread by viruses. Spread occurs before insecticide kill the aphids.