Oil palm pest

Researchers at Britain's University of Bath say they have developed a new technique to detect a strain of a fungal disease called Fusarium oxysporum, which is specific to oil palms.

Palm oil - as used in foods and biodiesel - is a product cultivated from the oil palm tree. The tree is native to tropical Africa, where it was first grown more than 5,000 years ago.

It is now commercially grown and harvested in other regions - mainly in Southeast Asia, where Malaysia and Indonesia dominate world production of palm oil.

Africacontinues to play an important role as a producer of seed for genetic diversity.

But the fungal disease has the potential to hamper the use of African seed in Southeast Asia.

Greater diversity

"Southeast Asia needs greater diversity to breed trees with various characteristics and imports seed from Africa - the home of the oil palm - for that very reason," says Professor Richard Cooper from the Department of Biology and Biochemistry at the University of Bath. "But the problem is that the pathogen Fusarium oxysporum is endemic in Africa and is not found in Southeast Asia."

The problem is made more complex by the fact that the fungus Fusarium oxysporum is common in various soils.

"It affects many different hosts, like potatoes and tomatoes in addition to oil palm trees, but each in a specific way," says Cooper. "While most forms of Fusarium are harmless for oil palms, one clearly isn't, so we need a specific probe to detect the oil palm form of the pathogen."

Finding a tool to detect the Fusarium oxysporum that affects oil palm trees has been a difficult task.

Cooper and his team studied the fungus' molecular capability to cause disease, known as its "virulence." Over time, these capabilities have adapted to the tree.

But above all, the researchers applied genetic fingerprinting techniques.

Zooming in on a gene

"We zoomed in on a gene in the fungal pathogen," says Cooper. "And we found one that appears to be unique to the oil palm form of the fungus Fusarium oxysporum."

The discovery is significant because it essentially pinpoints the specific strain that causes disease in oil palm trees. As a result, seeds that contain harmless strains of the fungus don't have to be destroyed.

Today, seeds from Africa are checked for fungus at a center near London before they can be exported. If any form of Fusarium oxysporum is found on the seeds, they are destroyed.

The new research will help save some seeds from destruction. But Cooper and his team are still currently fine-tuning their technique.

"We need to devise a test process that works not just in our lab but can be handled routinely in other labs by technicians," says Cooper. "It has to be easy to use."

Big exporters

The team has also researched Ganoderma, a fungus that causes extensive oil palm yield losses in Malaysia and Indonesia. 

Diseases like Ganoderma and Fusarium frequently occur in agricultural crops because they are grown on a large scale as monocultures of genetically identical plants.

Palm oil is a key export for Malaysia and Indonesia. Such diseases are a major threat to the livelihoods of growers. "Palm oil has helped lift many small growers out of poverty," says Cooper. 

Malaysiaand Indonesia are responsible for 86 percent of world production of palm oil - about 48 million tons a year, worth more than $46 billion (37.6 billion euros).

But the industry is also often accused of unsustainable land-clearing practices to enable larger scale cultivation of palm oil.

Author: John Blau
Editor: Zulfikar Abbany