Rainfall suspected culprit in leaf disease transmission

Nov 21, 2011

Rainfalls are suspected to trigger the spread of a multitude of foliar (leaf) diseases, which could be devastating for agriculture and forestry. Instead of focusing on the large-scale, ecological impact of this problem, researchers from the Massachusetts Institute of Technology (MIT) in Cambridge and the University of Liege in Belgium are studying the phenomenon from a novel perspective: that of a single rain droplet.

"One may easily picture that a raindrop impacting a contaminated leaf grabs some of the pathogens there before being ejected and flying towards some healthy plant in the neighborhood," says University of Liege assistant professor of engineering Tristan Gilet, who will present the team's research at the upcoming meeting of the American Physical Society (APS) Division of (DFD) in Baltimore, Md., along with MIT colleagues Lydia Bourouiba, a postdoctoral associate, and John Bush, professor of applied mathematics. But a more plausible scenario, Gilet continues, is that bacteria, viruses, and fungi dissolve into rainwater sitting on the surface of a leaf, and that this disease-carrying rainwater is then pushed off the leaf by other raindrops.

Using a high-speed camera to film artificial rainfall on a series of plants, the team identified two patterns of droplet ejection. The first is direct: a raindrop hits pathogen-infested water on a leaf and splashes some of it off.

The second is indirect: a hits the , whose violent movement ejects some of the disease-carrying water that had been sitting on it. From their modeling and experiments, the team concludes that the direct splashing method is a more efficient disease spreader for relatively large and rigid leaves, while smaller and more pliant leaves are more likely to be affected by the indirect method.

The cost of is estimated at three billion dollars a year in the United States alone, the researchers write. They say they hope their work will provide some guidance for farmers, by providing suggestions for the optimal spacing between plants, for example.

Explore further: First in-situ images of void collapse in explosives

More information: The talk, "Foliar disease transmission: insights from fluid dynamics," is on Monday, Nov. 21. Abstract: meeting.aps.org/Meeting/DFD11/Event/155026

Provided by American Institute of Physics

not rated yet
add to favorites email to friend print save as pdf

Related Stories

Can a drop of water cause sunburn or fire?

Jan 11, 2010

To the gardening world it may have always been considered a fact, but science has never proved the widely held belief that watering your garden in the midday sun can lead to burnt plants. Now a study into sunlit water droplets, ...

Can a single layer of cells control a leaf's size?

Feb 25, 2010

Ever looked carefully at the leaves on a plant and noticed their various sizes and shapes? Why are they different? What controls the size and shape of each individual leaf? Very little is known about the developmental ...

Debut of the first practical 'artificial leaf'

Mar 27, 2011

Scientists today claimed one of the milestones in the drive for sustainable energy — development of the first practical artificial leaf. Speaking here at the 241st National Meeting of the American Chemical Society, they ...

Recommended for you

First in-situ images of void collapse in explosives

14 hours ago

While creating the first-ever images of explosives using an x-ray free electron laser in California, Los Alamos researchers and collaborators demonstrated a crucial diagnostic for studying how voids affect ...

New approach to form non-equilibrium structures

Jul 24, 2014

Although most natural and synthetic processes prefer to settle into equilibrium—a state of unchanging balance without potential or energy—it is within the realm of non-equilibrium conditions where new possibilities lie. ...

Nike krypton laser achieves spot in Guinness World Records

Jul 24, 2014

A set of experiments conducted on the Nike krypton fluoride (KrF) laser at the U.S. Naval Research Laboratory (NRL) nearly five years ago has, at long last, earned the coveted Guinness World Records title for achieving "Highest ...

User comments : 0