• 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.

Sweetpotato feathery mottle virus, internal cork disease of sweetpotato

Sweetpotato feathery mottle potyvirus; the abbreviation is SPFMV; there are different strains: ordinary (O), russet crack (RC), East African (EA), and severe (S).