Table 4.2: Summary of risk assessments for quarantine pests for fresh taro from all countries where pests are present

This chapter provides information on the management of quarantine pests identified with an unrestricted risk exceeding Australia’s appropriate level of protection (ALOP). In estimating the unrestricted risk, existing commercial production practices and minimum border procedures in Australia were taken into consideration. The proposed phytosanitary measures are described below.

1.25Pest risk management measures and phytosanitary procedures

Specific pest risk management measures, including an operational system, are proposed for fresh taro corms from all countries to reduce the restricted risk to a level that achieves Australia’s ALOP.

This pest risk analysis has been conducted on corms of both the large and small corm varieties of taro. Corms of large corm taro are traditionally marketed with a short tuft of petiole bases attached to protect the apical bud and ensure the corms stay physiologically active, which delays the development of storage rots. Corms of small corm taro are cormels (daughter corms) that do not have petiole bases attached at the apical end.

The importation of small corm taro (Colocasia esculenta var. antiquorum) remains prohibited until further notice. However, countries that are able to demonstrate freedom from Colocasia bobone disease virus, Taro vein chlorosis virus and Tomato zonate spot virus may apply for access for small corm taro. Applications will be assessed on a case-by-case basis.

The specific pest risk management measures proposed for fresh taro corms from all countries are summarised in Table 5.1.

Table 5.1: Phytosanitary measures proposed for quarantine pests of fresh taro corms

Pest	Common name	Measures
Arthropods
Tarophagus proserpina	Taro planthopper	Inspection and remedial action for taro from countries where present Topping of corms of large corm taro from countries where present
Straminopila
Phytophthora colocasiae	Taro leaf blight	Area freedom from taro leaf blight
Viruses
Colocasia bobone disease virus	Colocasia bobone disease	Topping of corms of large corm taro from countries where present Prohibition of corms of small corm taro from countries where present
Taro vein chlorosis virus	Taro vein chlorosis
Tomato zonate spot virus	Tomato zonate spot

1.25.1Management for taro planthopper

Tarophagus proserpina has been assessed to have an unrestricted risk estimate of ‘low’ for taro corms imported from countries hosting this pest, and additional measures are therefore required to manage this risk.

The major risks from Tarophagus proserpina are eggs laid in the petioles or petiole bases on the corm, or nymphs or adults hiding in the petioles. Taro planthoppers are known to establish via planting materials. Corms of the large corm variety with petiole bases that could potentially be used for growing purposes present a significant risk.

The proposed risk management measures are:

• 
  inspection to ensure that taro corms infested with nymphs and adults of Tarophagus proserpina are identified and subjected to appropriate remedial action
  
• 
  topping of corms of large corm taro to remove the petiole bases that may carry eggs, nymphs and adults of Tarophagus proserpina.
  

The objective of these measures is to reduce the likelihood of importation for Tarophagus proserpina to at least ‘low’. The restricted risk would then be reduced to ‘very low’, which would achieve Australia’s ALOP.