- AUCKLAND (AFP) - Unknown to lovers of ice cream, milk shakes, coffee and
countless other taste-bud delights, the worlds second most lucrative spice
has been in serious trouble -- but fortunately some New Zealand biologists
have saved it.
Vanilla (vanilla planifolia), after saffron the most sought after spice,
has lately been hit by viruses but the University of Auckland School of
Biological Sciences has nailed the problem and in the process become an
unlikely authority.
"It's turned out to be a classic problem of mono-cultures," biologist
Michael Pearson of the university told AFP.
"People are starting to grow it intensively and so you get these problems."
Vanilla is the bequest of Aztec emperor Montezuma, he of "Montezumas
revenge" fame in Mexico. When Hernan Cortes and his conquistadors
showed up in 1520 Montezuma was drinking a beverage made up of powdered
cocoa beans, ground corn and flavoured with ground black vanilla pods and
honey. Chocolate.
The vanilla vine grows wild in Mexico, carefully pollinated by a particular
bee. Outside Mexico it would grow happily enough but lacking pollination
its flowers never set seed, and without the seedpods, there was no spice.
The French had taken the plant to their Indian Ocean territory of Reunion
in 1819 but it was not until 1841 that a slave discovered a method of hand-pollinating.
Today Reunion produces around 20 tonnes of vanilla a year, making it the
sixth largest producer in the world.
Unhappily in 1858 scientists discovered a way of synthesising vanilla which
threatened the natural industry. The synthetic version remains a major
player today but Pearson says while it is 90 percent similar to real vanilla,
the 10 percent that exists only in natural vanilla contains up to 100 unique
compounds.
Madagascar, the French Indian Ocean territories of Comoros and Reunion,
French Polynesia, Fiji, the Cook Islands and Tonga are among the major
producers now while rumour in the industry says the biggest end user of
processed vanilla is Coca-Cola, whose recipe is a closely guarded secret.
Attracted by good financial returns, producers have taken the vine out
of the wild and now grow it plantation style.
It is a particularly labour intensive operation: hand pollination with
toothpick like slivers of wood and regular pruning to reduce vegetative
growth and force the vine, which has a life of around 15 years, to flower.
All seemed well but then plants started to be attacked by diseases which
stunted growth and rendered them sterile.
Initially aphids were blamed, but the plant has a tough skin and Pearson
said they never found any of them on diseased plants.
He had worked previously at the University of Papua New Guinea, studying
orchids and their problems. Vanilla is an orchid, and so when problems
began occurring in Pacific plants he was a natural choice.
When word of the Pacific problem got around, Reunion authorities invited
him there when increasingly serious problems were encountered with diseases
in vanilla grown intensively in shade-houses.
"Vanilla is historically very important to Reunion and is almost part
of its national identity," he says, adding that the locals seem to
add it to everything they eat and drink.
He joined up with Reunion student Karin Farreyrol, now doing a doctorate
here, and isolated at least six different viruses.
The specialist journal New Agriculture says the two have most recently
isolated the cucumber mosaic virus, which can do serious damage. Other
viruses show no symptoms.
In French Polynesian plantations 23 percent of vanilla plants (of the variety
Vanilla tahitensis) showed virus-like symptoms contained the cucumber mosaic
virus. These plants were severely stunted and distorted and any flowers
that developed were sterile.
Vanilla around the world shows other viruses common to all, although on
Reunion the New Zealanders found a previously unknown rhabdo (or "bullet-shaped")
virus in their vanilla leaf samples.
Pearson said some of the viruses were producing total mortality on plantations.
The plantation approach and the involvement of so many human hands guaranteed
the viruses would be spread among the plants.
He says the best way to fight it will be to develop simple diagnostic tests
in the field that can assist in the detection and control of viruses.
"We are confident we will be able to do this," he said.
It was important too, he said, to ensure that only clean planting, with
virus-tested material being used. Any vanilla with viruses has to be removed
and destroyed.
Growers are following his advice.
"We are the world experts on vanilla virus, but that is because we
are the only ones doing it," Pearson said.
- Copyright © 2001 AFP
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