A push for pineapples to be imported into Australia from Malaysia could leave the Queensland pineapple industry at risk.
The two main pineapple industries in Australia concern the processing of pineapples, such as canning, and the ‘fresh’ industry, a market which has shown huge growth over the past decade. The Queensland pineapple industry as a whole is worth $80 million.
Yet, there is currently a push to import fresh de-crowned pineapples into the country from Malaysia. Ms Michelle Landry, a politician representing Capricornia in Australia, is opposing this because of the potential spread of a disease from Malaysia into Australia.
This disease is caused by the bacterial pathogen Erwinia chysanthemi and has been known to infect up to 40% of a plantation in Malaysia. On a side note, the taxonomic position of this species is currently being disputed, but will be referred to as E. chysanthemi for the purposes of this article.
E. chysanthemi is responsible for two diseases in pineapple, fruit collapse and bacterial heart rot (which affects the stem and leaves). Bacterial heat rot is usually seen in young plants and can cause the formation of lesions of leaves.
Fruit collapse is the more serious of the two disease and occurs when the bacteria enters through the flower, the bacteria then waits until the fruit matures. This inactive period can last around two months, and it is this initial lack of disease symptoms has led to the disease being nicknamed the ‘ghost disease’ by farmers. Symptoms will begin to appear two or three weeks prior to ripening. These symptoms include exudation of liquid, change in colour of the fruit and production of gas within the fruit. If the gases produced in the fruit do not escape they can build up and cause the pineapple to explode.
The pineapples imported from Malaysia would be de-crowned, meaning the leaves on top would have been removed, therefore the pathogen cannot be carried on the leaves but could be present in the fruit, but undetected due to lack of symptoms.
An assessment by the Department of Agriculture, Forestry and Fisheries (DAAF) concluded that fruit collapse is unlikely to be a problem in Australia. In their report, DAAF point out that only a small number of pineapples will be imported into Australia and it is unlikely these will be disposed of near sites where pineapples are grown. Proper disposal of infected pineapples would further limit transmission.
Opponents, such as Ms Landry, claim that the DAAF is wrong and this bacterial heart rot poses a serious threat to the pineapple industry. They claim the risk assessment performed by DAAF is biased to produce low-risk outcomes.
Most public opposition is coming from pineapple companies based in Queensland. These companies have been accused of opposing the import of pineapples because they fear the competition. They have denied this and say they are concerned of the threat the disease poses.
Ms Landry speaking about the threat that exploding pineapples could have
And a news report
There is currently no known way to treat infected pineapples or eradicate the disease, the only way to manage it is to remove infected pineapples. It has been estimated that around 2% of fruit have the infection but do not show infection, though this figure is disputed.
Therefore, if the disease does get into the Australia, there will be no way to control it. The report by the DAAF found that if the bacterium does manage to establish itself in Australia, it will be able to quickly spread between plants. Despite this DAAF summarised that overall there is little risk associated with importing pineapples from Malaysia.
Fruit collapse is a serious disease, particularly because there is no way to treat it at present. What matters here is the likelihood of the pathogen entering Australia and successfully establishing itself, because once established this disease could prove highly destructive to the companies growing pineapples.
Let’s hope 2015 will be a good year with a distinct lack of exploding pineapples in Australia.
And it’s always best to finish on a bang (even one that was not caused by a build up of gases due to a pathogen).
Kaneshiro, W. S., Burger, M., Vine, B. G., de Silva, A. S., and Alvarez, A. M. 2008 Characterization of Erwinia chrysanthemi from a Bacterial Heart Rot of Pineapple in Hawaii. Plant Disease 92, 1444-1450.
Header from ‘Psych’ tv series, series 1 episode 15.