Foliar disease transmission : drop impacts and interactions
Orateur : Lydia Bourouiba
The Fluid Dynamics of Disease Transmission Laboratory, MIT, USA
Résumé : Statistical correlations were reported between rainfall and crop disease outbreaks, suggesting that rain is a culprit in the dispersal of foliar pathogens. The mechanisms involved remain however poorly understood. In this combined experimental and theoretical study, we unveil the mechanisms at play when raindrops impact infected plant leaves. We discuss how fluid fragmentation is critical in shaping the patterns of contamination resulting from emission of pathogen-bearing droplets driving rain-induced epidemics. In particular, we identify and discuss two main fragmentation processes that shape rain-induced dispersal mechanisms and introduce and characterize new modes of drop-drop interactions on surfaces of average wetting that can shape pathogen transmission for a range of crops. Finally, we revisit the radially expanding sheet in the air formed from some of these impacts. We show results that allow to unify the thickness profile of unsteady expanding sheets in the air and quantify the effect of the surface on the dynamics of such sheet. These results are important to improve understanding of transmission in the field and so guide risk assessment and intervention strategies to mitigate crop contamination.
Date et lieu : le Vendredi 23 Juin 2017 à 11h00, salle de séminaire IRPHE