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

Whole plants should be planted into sufficiently sized pots (eg 3 L minimum) containing
50:50 (v/v) pasteurised peat:pumice planting media and a few grams of slow-release fertiliser
with trace elements (e.g. Osmocote ® ). Nodal cuttings should be taken from growing vines to
maintain the clone and facilitate quarantine examination and testing. Cuttings with one or
two leaves and at least two nodes can be rooted directly in pasteurised pumice sand or perlite
before transferring to planting media. It would be worth preserving clonal material in tissue
culture as a back-up resource, and to preserve any established virus-free status.
Plants in tissue culture
Tissue culture plantlets can be sub-cultured after arrival by cutting into nodal sections and
placing into new tissue culture vessels with fresh nutrient media (e.g. Murashige and Skoog
media).
Plantlets to be tested are carefully excised from the tissue culture vessel and washed to
remove any remaining agar and planted into pots of planting media containing 50:50 (v/v)
pasturised peat:perlite or 50:50 (v/v) peat:vermiculite. The plantlets must be protected from
desiccation for approximately three weeks by covering initially with a vented plastic tub or
bag. Alternatively, the plants can be misted regularly to keep the planting media moist, and
to maintain a high relative humidity. Pots should be placed in bright light, but not direct
sunlight during the three weeks. After this period, any coverings should be removed and the
plants moved to higher light intensity.
5.3 Pollen
Anthers can be collected from mature but unopened flowers and dried in warm, light
conditions. Following this drying period, pollen should be collected into a centrifuge vial or
into gel capsules and stored at 4°C in a sealed container in the presence of a strong desiccant
such as calcium chloride.
6. INSPECTION
The inspection requirements for the operator of the facility are set out in the “MPI
Biosecurity Authority Standard PBC-NZ-TRA-PQCON”
(http://www.biosecurity.govt.nz/files/regs/stds/pbc-nz-tra-pqcon.pdf )
Photographs of symptoms caused by significant regulated diseases can be found in Appendix
1. However, please note that pot-grown sweetpotato plants can be prone to nutrient
deficiencies if not adequately fertilised and nutrient deficiencies can resemble virus infection,
e.g. chlorosis and necrosis. Symptoms related to nutrient deficiencies can be found in
Appendix 2. Further information on nutrient deficiencies is described in Clark & Moyer
(1988).
Ipomoea Post-Entry Quarantine Testing Manual · November 2012
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