Posted by: Mahdi Ebrahimi | September 12, 2007

Iranain scientist find new way for organic agriculture

saber miresmaili

A University of British Columbia researcher has discovered a new way to fight pests in vegetable crops: By listening for the plants’ own distress call.

Every year, insects such as aphids and mites wipe out as much as 10 per cent of vegetable crops in B.C. — costing the industry tens of millions of dollars.

At the moment, greenhouses rely on their staff to spot such outbreaks — by checking sticky traps for insects and inspecting plants for signs of trouble.

The problem is many pests are so small that, by the time they can be seen, it’s too late to do anything.

Saber Miresmailli, a PhD student in UBC’s Land and Food Systems program, thinks he has a better idea.

It turns out many vegetables have a kind of built-in distress call — releasing chemicals into the air when they’re in trouble.

The warning system is so sensitive, Miresmailli said, that some plants sound the alarm even before an infestation begins — when insects first begin laying eggs on their leaves.

Exactly why plants do this is unclear, said Miresmailli.

One theory is the chemicals serve as a kind of natural insect repellent.

Another is that they attract even bigger insects, which then feed on the invading pests.

There is even some evidence the chemicals are a way for plants to warn their neighbours of impending attack — so they can take steps, like emitting toxins, to save themselves.

Whatever the reason, it’s clear plants have a way of letting the world know they’re in trouble.

The challenge is to figure out what they’re saying.

Plants “can communicate with the environment,” said Miresmailli. “It’s just a matter of us learning the language.”

Over the past 21/2 years, Miresmailli has been trying to translate that language — building a database of the types of chemicals tomato, cucumber and pepper plants release when they’re in distress.

Once the database is complete, he plans to build a device that can sniff out a plant’s chemical warning signals using the same basic technology as bomb-detecting machines at airports. Miresmailli said that device, which is still at least five years away, could sniff around a big greenhouse and pinpoint trouble spots on a map.

By identifying infestations early on, he said, growers could save more of their crops — and use harsh pesticides less.

In some cases, said Miresmailli, they may even be able to pluck off insect larvae by hand before an outbreak occurs.

Jonathan Bos is director of special projects with Village Farms Canada, one of the largest greenhouse growers in B.C.

He said he’s excited by Miresmailli’s research, which is partly funded by the B.C. Greenhouse Growers’ Association.

“It looks like he could almost have an early warning system for pests and disease,” he said.

Some of the chemicals plants release can actually be detected with the human nose — including limeonene, which has a citrus smell.

Indeed, in a series of blindfolded tests Miresmailli conducted with experienced farmers, the vast majority were able to tell which plant was infested with pests and which one was healthy — just from the smell.

“It was amazing,” he said. “They say a good grower should be able to read his plants.”

Miresmailli said he hopes his device will be able to do the same — only on a much larger scale.



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