Negative tests for plum pox

A suspected incident of Plum pox has almost certainly been ruled out in tests conducted by the Ministry of Agriculture and Forestry (MAF) and the United States Department of Agriculture (USDA).

Samples from a single non-commercial plum tree in the Waikato were extensively tested by MAF and sent to the USDA on the 18th March for further verification after initial results in New Zealand were negative.

Barney Stephenson of the Ministry of Agriculture and Forestry’s (MAF) Plant Biosecurity group is relieved by the findings and very appreciative of the manner in which industry worked alongside MAF in managing the scare.

“Potentially we were dealing with a virus that could ruin our summerfruit industry. Although at this stage we would like to confirm the cause, we know it is almost certainly not plum pox.”

“Summerfruit New Zealand were a crucial part of our response and it has been an extremely useful test of our response system,” he said.

A number of tests were used including Enzyme Linked Immuno�Sorbent Assay (ELISA), a sensitive serological test able to detect the presence of a virus in plant tissues including those that appear symptom free, and Polymerase Chain Reaction (PCR), an even more sensitive test.

Plum pox is a notifiable disease under the Biosecurity Act 1993. Four strains of the plum pox potyvirus exist. In infected countries it is commonly spread by grafting and by aphids and can devastate fruit bearing varieties from the Prunus family including peaches, apricots, plums, nectarines, almonds and cherries, causing fruit to be unmarketable and decreasing the yield.

MAF was able to respond promptly to the potential outbreak through the quick actions of a member of public who noticed the apparently diseased fruit.

“Early detection is key to the success of our exotic disease and pest response programmes. MAF is dependent upon an alert public to keep us informed, we all have a responsibility to protect New Zealand from unwanted pests,” Dr Stephenson said.

Background information on plum pox is available at http://www.maf.govt.nz/plum�pox and http://www.summerfruitnz.co.nz

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