QUARANTINE: by Patrick J. ByrneNews Weekly
AQIS caught out in apple documents
, December 16, 2000
Important documents have come to light on how the Australian Quarantine and Inspection Service (AQIS) came to its draft recommendation to allow into Australia New Zealand apples, despite the risk to Australia of fire blight, the "foot and mouth disease" of horticulture.
The documents reveal that 29 questions were put to 15 fire blight experts around the world. While the AQIS Import Risk Assessment (IRA) gives the impression that all 15 scientists responded, in fact only six replied to the questionnaire.
Given the number of scientific studies cited in the 214 page report, up to 70 scientists could have been asked for a scientific assessment of the risk of apple imports, but were not asked.
The focus of the questions was narrow. The questions lacked statistical rigor. There were no numerical scales given by which scientists could rate various risks. They were left to make up their own risk descriptions. Several of the scientists complained that some of the questions were poorly constructed.Varying responses
Despite the widely varying responses of the experts on critical questions, selective quoting allowed AQIS to conclude that the probability of imported NZ apples establishing fire blight in Australia was "low."
The AQIS report assumes that the only scenario by which fire blight could be established in Australia would be through discarded apple cores.
Other possibilities like the following were not considered - the discarding of infected apple tree leaf/branch litter that could be transported with the apples; or supermarkets throwing out spoiled apples; or waste apples, branch/leaf litter being left in a NZ container which is then transported to an Australian apple orchard where the waste is thrown out to compost in the orchard.
The AQIS report also refers to fire blight being a fragile, or relatively fragile, bacterium. Yet none of the six scientists who responded referred to it as being fragile. In fact, one said it could live up to six weeks in the calyx, the indented underside, of apples in favourable conditions.
Many responses by the scientists give a different picture as to the risk of fire blight than what was conveyed in the AQIS report.
Asked if fire blight in discarded discaapple cores could lead to its establishment in favourable times like in spring, the replies varied from "no," to "it should be possible" although not documented in the literature.
Asked how long the bacterium remains viable in the calyx of discarded apple cores, responses varied. One said the bacterium would decline rapidly to zero. Another said it would take days or weeks to die off. Another said it could survive up to six weeks.
Asked how long fire blight could remain viable on an insect that had visited an apple core discarded into the Australian environment, most said they didn't know. One said the bacterium could remain viable on an insect for two weeks.
AQIS recommended NZ orchards have a 50 meter buffer zone around orchards wanting to export to Australia. When asked what would be a good sized buffer zone, answers from the scientists varied from 20-30 meters, to 100 meters, to 500 meters, to 5-10 kilometers. One said that the protection would be proportional to the size of the buffer zone.
While AQIS has claimed that dipping apples in chlorine would kill any fire blight present on imported apples, including in the calyx of the apple, the responses of the scientists were quite different. One said it would work, if the chlorine penetrated the calyx. Others were "unclear" or "doubtful" if chlorine dipping would be effective.
On the critical question 24, "What is the risk of introducing fire blight via trade in apples to countries free from it?" the AQIS report concluded that the probability was "low". Yet consider this. Dr Satish Wimalajeewa, did not have his response to this question reported by AQIS. He said that the degree of risk "will depend upon the volume of fruit imported. He warned "[t]hus, whether the Ea bacteria enter Australia in low numbers or in high numbers, in or on apples or propagating material there will be a certain amount of risk. It is for this reason too that AQIS does not permit the importation of viable virulent cultures of Ea for research purposes to be conducted even in high security containment facilities."
When another scientist, Dr Larry Pusey, was asked question 24, he said, the probability is near to zero." What AQIS did not report was his reply to an earlier question, "Where low numbers of fire blight bacteria are present on apple fruit, how would you describe the risk for the importing country?" To that question Dr Pusey said, "The risk should not be taken by a country free of the disease."