Early detection of 'olive tree leprosy' with drones

This file photo taken on February 11, 2016 shows olive trees infected by the bacteria "Xylella fastidiosa" in Gallipoli near Lecce, in the Puglia region. (AFP)
Updated 26 June 2018
0

Early detection of 'olive tree leprosy' with drones

  • The bug has also attacked orchards in Spain and France, and both Greece and Portugal are bracing for its likely arrival
  • The only way to fight the spread of what is known as "olive tree leprosy" is to destroy diseased trees

PARIS: A bacterial infection ravaging olive orchards in southern Europe can be detected from small planes or drones well before symptoms appear, offering panicky growers the prospect of an early warning system, scientists said Monday.
Using high-tech cameras that detect heat and the electromagnetic spectrum from X-ray to radio waves, researchers were able to spot diseased trees that, on the ground, still seemed healthy, they reported in the journal Nature Plants.
"After infection, it takes four to 14 months before visual symptoms are observable by plant pathologists in the field," lead author Pablo Zarco-Tejada, an agricultural engineer at the European Commission's Joint Research Centre in Ispra, Italy, told AFP.
"The problem is that during this entire time the tree remains a potential source of infection."
Once Xylella fastidiosa bacteria -- carried by tiny sap-sucking insects known as leafhoppers -- take hold, there is no cure and the plant is doomed.
The only way to fight the spread of what is known as "olive tree leprosy" is to destroy diseased trees.
"Early detection is critical for the eradication of the bacteria," Zarco-Tejada said.
Since it hit the Apulia region in 2013, the microscopic pathogen has killed more than a million olive trees in Italy, and 10 million more are currently affected.
The bug has also attacked orchards in Spain and France, and both Greece and Portugal are bracing for its likely arrival.
Some 350 plants are vulnerable, including grape vines, citrus and almond trees.
Known in the United States as Pierce's disease, it devastated California vineyards in the late 19th century.
To test their approach, Zarco-Tejada and international team of researchers fitted thermal and hyperspectral cameras on a small plane, and then analysed images of orchards.
At the same time, they tested olive trees on the ground for infection.
They found that the bacterial infection can be remotely detected three to six months before visible symptoms appear.
"We extracted the spectral signature and the temperature from each single tree crown," Zarco-Tejada said.
The data were then fed into a model built with machine-learning methods.
The cameras can be easily installed on planes or drones, similar to ones used for aerial photography and surveillance. The cost would depend in part on the size of the area covered.
The insect-borne pathogen has likely spread more quickly as global warming takes hold, according to a study published earlier this year in the journal Biorxiv.
But a more immediate factor in its expansion is probably global trade, the study said.
The authors are currently measuring for Xylella fastidiosa in almond orchards in central Spain.
Italy and Spain together account for nearly 70 percent of global olive oil output, according to the International Olive Council (IOC).


Crater bigger than Paris is discovered under Greenland ice

Videographic looking at the importance of ice shelves. A study shows that Greenland and Antarctic ice sheets will continue to shrink this century, even if warming is limited to less than 2 degrees Celsius above pre-industrial levels. (AFP)
Updated 15 November 2018
0

Crater bigger than Paris is discovered under Greenland ice

  • The discovery was initially made in the 2015 but an international team of researchers has been working to verify the findings ever since
  • There would have been debris projected into the atmosphere that would affect the climate and the potential for melting a lot of ice

TAMPA: A massive iron meteorite smashed into Greenland as recently as 12,000 years ago, leaving a crater bigger than Paris that was recently discovered beneath the ice with sophisticated radar, researchers said Wednesday.
The crater is the first of its kind ever found on Greenland — or under any of the Earth’s ice sheets — and is among the 25 largest known on Earth, said the report in the journal Science Advances.
The impact of the 19-mile (31 kilometers) wide crater under the Hiawatha Glacier would have had significant ripple effects in the region, possible even globally, researchers said.
But its story is just beginning to be told.
“There would have been debris projected into the atmosphere that would affect the climate and the potential for melting a lot of ice, so there could have been a sudden freshwater influx into the Nares Strait between Canada and Greenland that would have affected the ocean flow in that whole region,” said co-author John Paden, courtesy associate professor of electrical engineering and computer science at Kansas University.
“The evidence indicates that the impact probably happened after the Greenland Ice Sheet formed, but the research team is still working on the precise dating.”
The discovery was initially made in the 2015 but an international team of researchers has been working to verify the findings ever since.
The initial finding was made with data from NASA’s Program for Arctic Regional Climate Assessment and Operation IceBridge.
More data was collected since then, using more advanced radar technology.
“So far, it has not been possible to date the crater directly, but its condition strongly suggests that it formed after ice began to cover Greenland, so younger than three million years old and possibly as recently as 12,000 years ago — toward the end of the last ice age” said co-author professor Kurt Kjaer from the Center for GeoGenetics at the Natural History Museum of Denmark.
Researchers plan to try and recover material that melted from the bottom of the glacier to learn more about its timing and effects on life on Earth at the time.