Pineapples: same story, same risk, other diseases

We know that the banana is under serious threat. Worldwide, the most cultivated cultivar of the banana is the ‘Cavendish’. It replaced the ‘Gros Michel’, which succumbed to the Panama Disease in the 1950s. The ‘Cavendish’ was chosen because it was able to resist the fungus that killed the ‘Gros Michel’. But the fungus has mutated and the new version, called Fusarium tropical race 4 (TR4), originated in Taiwan and is quickly creating havoc in plantations in Asia, the Middle East and – recently – Africa.

Because all commercially grown bananas were identical cultivars of the ‘Cavendish’, they are at risk of worldwide extinction, creating mass unemployment which will be quickly followed by starvation of the population of banana producing countries.

[Scarlet pineapple]

What about pineapples, you might ask. Like bananas, pineapples suffer from the same problem because one cultivar, the ‘Smooth Cayenne’, is grown around the world. It does not have the spiny edges of other types do have, it has a high yield, adapts well and has good characteristics for canning. The pineapple industry of the world is therefore dominated by the ‘Smooth Cayenne’, which is used both for fresh fruit and for processing.

Such a near-total reliance in crop cultivation is uncommon and is made even more unbelievable by the fact that the ‘Smooth Cayenne’ has been the backbone of the global pineapple industry for more than a century. First collected by Samuel Perrotet in 1919 in French Guiana, it was rapidly distributed and planted in other geographical regions.

A virtual mono-culture also means that diseases may appear in far-away corners of the globe and these can spread like wildfire because of the fact that all these pineapples are genetically the same. Which is exactly what is happening now: diseases like (bacterial) heart rot or (fungal) pineapple black rot are already widespread and are now common and destructive pineapple diseases in the world. In Malaysia, both bacterial heart rot and fruit collapse caused by Dickeya spp. are endemic, with field crop losses recorded of up to 40 per cent. It is feared that the disease may spread to Australia’s Queensland, that has a pineapple industry worth A$80 million a year and underpins more than 1,000 jobs. Hawaii has the only commercial pineapple crop in the USA and thus represents the entire U.S. industry but when bacterial heart rot of pineapple was reported in Hawaii in 2003 and reoccurred in 2006, it was a serious blow to the industry.