Using capillary forces to estimate the adhesion strength of Magnaporthe grisea spores on glass

The Magnaporthe grisea is a fungus whose spores strongly adhere to plant leaves, and to solid surfaces in general. In this note, we give an estimate of the adhesion force, F_det, of a spore on a glass surface, in water. F_det is defined as the force to be applied to a spore to pull it out from the surface. In our experiments, spores are detached from the glass in a few milliseconds by means of a capillary force. The latter is provided by a water/air or a water/oil interface, in contact with the spore body. We thus find F_det of the order of 10⁻⁶ N.