Fears over melon virus

An Ord Valley grower says more needs to be done to ensure the devastating cucumber green mottle mosaic virus does not make its way into WA.

CGMMV was confirmed in the Northern Territory on October 3, with the Department of Primary Industry and Fisheries declaring quarantine zones in areas near Katherine and Darwin.

The disease, which was discovered in NT watermelons but can affect fruit and vegetables including all melons, pumpkin, squash, cucumber and zucchini, poses no risk to human health but makes the produce unsellable.

Bothkamp Australia Farm's Christian Bloecker said the discovery in the NT was extremely worrying given its proximity to Kununurra and how easily CGMMV can spread.

"From what I understand, the affected farms are now quarantined because of something that was completely out of their control," he said.

"If, as has been suggested, the CGMMV has entered these properties via seed or seedlings, it raises the prospect that many more farms will test positive and be quarantined.

"You have to feel sorry for these farms as their businesses have been shut down through no fault of their own, and what worries us is that we could be next."

Symptoms of CGMMV infection can vary but affected melon plants can display stunted leaves and a mosaic-like mottling.

Affected fruit can display discolouration, cavities and soft, mushy areas within the flesh, while it might also appear malformed.

Mr Bloecker said he was concerned it had taken the NT's DPIF so long to act on initial reports that the virus might be present.

"According to the NT DPIF timeline of events, the first samples were collected on July 3 and it was not till September 4 that diagnosis was confirmed," he said.

"Even after this positive confirmation, it wasn't until the beginning of October that actual quarantine restrictions were put in place.

"If one were cynical, one might suggest that, intentionally or not, quarantine restrictions were not put in place until the majority of the melon growers in the NT had finished or nearly finished harvesting, so as to reduce the financial impact on the NT melon industry."

NT DPIF chief plant health manager Stephen West said CGMMV could survive for long periods on machinery and equipment.

He said it was contagious and transmitted by contact, but could be destroyed at high temperatures.

"Information about the required compliance measures has been provided to each property to ensure that CGMVV-infected plants and plant material are eradicated," he said.

All watermelon crops in the NT quarantine areas will be destroyed within two weeks by burning and deep burial.

Plastic mulch from the affected crops will also be destroyed.

Under quarantine, it is prohibited to move off the property any watermelon plants, fruit or items associated with the production of the plants, move equipment unless it has been disinfected and inspected, and propagate or plant watermelon plants.

A statement released last week by the NT DPIF said, based on overseas experience with outbreaks of CGMMV, the quarantine could be in place for up to two years to ensure eradication.

"It is likely that crops that are not hosts for the virus could be grown in the quarantine area around 12 months following the destruction and treatment of the virus - the situation will be reviewed at that time," the statement said.

Mr Bloecker said cardboard bins and pallets that the melons were transported in also needed to be assessed as a quarantine risk.

"Thousands of these bins filled with melons have left the NT, headed to the central markets or major supermarket distribution centres in Perth, Adelaide, Melbourne, Sydney and Brisbane," he said.

"We know these bins get reused - the secondhand bins are bought by growers, they get taken back to melon farms, are filled with new produce, and they are then sent to market again.

"This raises a much bigger question, in that is it possible that the apparent lack of decisive implementation of quarantine measures has put the whole Australian melon industry at risk?"

Mr Bloecker said growers had been in close communication with the local Department of Agriculture and Food and the Ord River District Co-operative to minimise the risk.

DAFWA issued a warning last week for people to be extra vigilant in preventing the spread of CGMMV to WA.

Plant biosecurity director John van Schagen said they were working with the NT and other jurisdictions on a co-ordinated response and were awaiting further tracing and surveillance information.

"We ask growers to be vigilant for exotic pests or diseases, and check their crops for signs of CGMMV," he said.

WA growers who suspect the presence of CGMMV should contact DAFWA's Pest and Disease Information Service on 1800 084 881.

"We also remind growers to follow farm biosecurity measures, which include restricting farm visitor access, using footbaths and cleaning and disinfecting tools and machinery," Mr van Schagen said.

Mr Bloecker said it would be devastating for the local melon industry if CGMMV were confirmed in Kununurra and farms were placed under quarantine for up to two years, as has happened in the NT.

"Most growers have now finished harvesting for the season, so let's hope that we are lucky and we remain CGMMV free," he said.

Information is available at www. dpif.nt.gov.au/cucumbervirus.