UV Fluorescent Powders as a Tool for Plant Epidemiological Studies

Some basic aspects of plant disease epidemiology remain largely unknown due to a lack of empirical study methods to experimentally manipulate the position of infections within a single plant or within a plant canopy and the dispersal behaviors of small insects that vector important plant diseases, for example. We present two methods using UV fluorescent particles that, when mixed in a 10% ethanol solution, can be used to create surrogate fungal infections on plant leaves and to field mark whiteflies in situ. When we used a custom-made experimental chamber to measure the velocity of falling particles, we found that the UV fluorescent particles had settlement velocities that overlapped with known fungal plant pathogen spores. In a separate experiment, field applied marks to whiteflies, Bemisia tabaci, were used to estimate straight-line insect vector displacement from source plants as a simple dispersal gradient over a limited distance in a 48 h period. The UV fluorescent particles and airbrushes were relatively inexpensive (USD < 100 total), easily sourced, and usable in a field setting. We believe that the approaches and methods shared in this manuscript can be used to design specific experiments that will fill important plant epidemiological knowledge gaps in future studies.