Image caption Fraxinus: Playing to uncover science of a deadly disease

The public are being asked to help in the fight against ash dieback by playing a computer game that analyses genetic data on the disease.

The Facebook game aims to use the power of social media to find a scientific solution to protecting ash trees from the Chalara fraxinea fungus.

Many of the UK's 80m ash trees are threatened by ash dieback.

Scientists believe some trees may have natural immunity to Chalara and could be used to grow resistant forests.

They hope to identify potential woodland survivors by studying the genetics of British ash trees.

They are also looking at the genetics of the fungus to find out more about how it spreads.

'Fun and engrossing'

Dr Joan Webber is principal pathologist and head of the tree health research group at the government agency Forest Research.

We can get a fast start on evolution rather than leaving these trees out there finding a way to fight the pathogen over decades or even centuries Dr Joan Webber, Forest Research

"The game itself is really helping with building our picture of what the genome is of ash," she said.

"And the reason we want to have more information about that is simply looking for resistance - looking for resistant individuals or the genes around resistance to Chalara in our ash trees."

The Fraxinus game, launched to the public on Tuesday, challenges players to match sequences of genetic "letters" represented by coloured leaf shapes.

This sorts genetic information into matching sequences and pinpoints genetic variation in the tree or the fungus.

Experts hope it will give clues to the origins of the disease, and help identify the best ash trees to grow in the future.

Dr Dan MacLean, of the John Innes Centre in Norwich, is the scientist who came up with the idea.

He told BBC News: "Primarily we designed the game to be fun and engrossing in and of itself.

"That's where the basic value is for the player - how we get the most out of it is if people want to come back to it and play it with their friends. That it's for a good cause is a bonus."

Prof Allan Downie, also of the John Innes Centre, said the aim was to harness "people power" to get cumulative information.

"By getting people in, by matching patterns, we might be able to identify what the diversity is of the different individual fungi that are causing this disease," he said.

Widespread damage

Ash dieback has caused widespread damage to ash populations in continental Europe, with losses in Denmark estimated at 60% to 90% of all ash trees.

However, some trees appear to have survived attack, raising hopes that these could populate future woodlands.

UK scientists have sequenced the genome of a resistant ash tree, as well as a native ash from England and samples of fungus from infected trees.

"We can get a fast start on evolution rather than leaving these trees out there finding a way to fight the pathogen over decades or even centuries," said Dr Webber.

The scientists say top gamers may have their names published in scientific articles for their role in helping analyse the genetic information.