New import controls on Australian curcurbits
The Ministry for Primary Industries (MPI) suspended Australian imports on fruit and vegetables of the cucurbit family, after the CGMMV was detected on Australian watermelon in midAugust.
The virus is a destructive disease of cucurbits, such as squash, pumpkin, cucumber and melon, and can cause severe yield losses. It only infects plants, so is not a concern for animal or human health.
That suspension was lifted on August 27, when new import requirements were put in place by Australia to manage the risk of GCMMV on host fruit arriving at the New Zealand border. An Industry Advice Notice (IAN) was issued in Australia to advise industry that NZ has revised the import conditions of CGMMV or host commodities.
MPI advised that from August 22, fresh cucurbit produce from Australia can only be imported after complying with the new additional conditions required for fresh watermelon (Citrullus lanatus) and pumpkin (Cucurbita pepo) fruit must be sourced from an area free from CGMMV; and that fresh honeydew melon/rockmelon (Cucumis melo), cucumber (Cucumis sativus), scallopini (Cucurbita pepo) and zucchini (Cucurbita pepo) must be produced in a pest- free place of production for CGMMV. The Manual of Importing Country Requirements (MICoR) in Australia has been updated to reflect the changed conditions. Approval for export to NZ is subject to an assessment against Area Freedom certification issued by the state and territory departments confirming the area’s freedom from CGMMV. Exporters sourcing produce from growers and suppliers to export to NZ will need to ensure that the property of production is registered with the department and approved for export. This is an additional measure and all other requirements in the Australia-NZ
Bilateral Quarantine Arrangement and on MICoR must be adhered to. CGMMV is a soil-borne plant virus which affects cucurbit crops such as watermelons, pumpkins, zucchinis and cucumbers, but is not harmful to humans.
The plant virus was first detected in the Northern Territory’s Katherine region in 2014 and at that time caused severe damage to the $60 million watermelon industry nearly decimating it, and has since been found on farms in Queensland and Western Australia. A spokesperson from the Australian Melon Association said the infected fruit found in NZ came from a Northern Territory farm found to have CGMMV, and the virus is extremely difficult to eradicate from soil once it is present on a farm.
Australian melon exports to NZ were worth $9 million in 2017, and melons were Australia’s fifth largest fruit export across all markets with NZ being their third largest market for melons. In Europe this virus disease was originally detected in 1975 in watermelon and melon with symptoms showing that the virus affects the young leaves with green and light green spots or yellow-green spots. These spots have a slower development rate than the rest of the leaf and where there is heavy infection young leaves are often deformed. The activity of the virus is reduced when the leaf ages and fruit drop (abortion) is common. The rest of the fruit are small and overall yield can be reduced by 25 percent or more if no control actions are taken into account. In the epidermis of the sick plants characteristic structures can be seen easily with a microscope. Temperature inactivation in juice occurs at 90 °C. Seed transition of eight to 10 percent from the beginning, which is enough to start the silent infection. Aphids and other sucking insects do not transmit the virus but with hydroponic the virus could spread out to up to 80 percent of the crop because the roots are touching.
Credit to University of California Credit to University of California Wikimedia Commons Wikimedia Commons ▴ Examples of GCMMV damage to leaf crops.