Ipomoea (Sweetpotato/Kumara) Post-Entry Quarantine Testing Manual

Note: Sweetpotato plants are sensitive to some pesticides and spray damage can induce
mosaic-like symptoms. In addition, plants suffering from nutrient deficiencies can show
leaf chlorosis and necrosis.
Interpretation of results
Symptoms on I. setosa usually appear within 2-4 weeks, and on I. nil around one week.
However, the severity of virus symptoms and length of time before they appear on the
indicator plants depends upon the virus and the amount of virus inoculum present in the
scion. The graft inoculation results will only be considered valid if:
(a) no symptoms are produced on the negative control (non-grafted) indicator plant; and
(b) the expected symptoms are produced on the indicator hosts with the positive control
(non-regulated virus). If SPFMV was used as the positive control, the following
symptoms will be produced on the indicator plants:
• I. setosa – vein clearing followed by remission.
• I. nil – systemic vein clearing, vein banding, ringspots.
The symptoms produced by each of the regulated viruses on the indicator species I. setosa
and I. nil are described below.
Sweetpotato caulimo-like virus:
• I. setosa – chlorotic flecks along the secondary veins and interveinal chlorotic spots on
leaves.
Sweetpotato chlorotic stunt virus:
• I. setosa – stunting, yellowing and leaf deformation, although symptoms maybe mild
depending on isolate.
• I. nil – stunting, yellowing and leaf deformation, although symptoms maybe mild
depending on isolate.
Sweetpotato leaf curl virus:
• I. setosa – curling of young leaves.
• I. nil – curling of young leaves.
Sweetpotato leaf speckling virus:
• I. setosa – chlorotic and necrotic spotting, dwarfing and leaf curling.
• I. nil – chlorotic and necrotic spotting, dwarfing and leaf curling.
Sweetpotato mild speckling virus:
• I. setosa – mild mosaic sometimes observed in first two true leaves.
Sweetpotato vein mosaic virus:
• I. setosa – systemic vein-clearing and mosaic.
• I. nil – systemic vein-clearing and mosaic.
Sweetpotato yellow dwarf virus:
• I. setosa – chlorotic leaf mottling.
Ipomoea Post-Entry Quarantine Testing Manual · November 2012
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