Methodologies for Particle Dispersion Experiments in Plant Canopies

As part of our ongoing work to study the mechanisms of fungal epidemiology in vineyards, the investigation of the transport physics of fungal spores has led to the development of new equipment and methodologies for use in performing and analyzing particle plume experiments. Although these techniques have been used specifically for spore and microsphere transport experiments, they could be tapped for use in a variety of different studies both in vineyards and in other canopy types. Between the years of 2009 and 2014, five field campaigns were performed by our team in commercial vineyards in Oregon's Willamette Valley. Over the course of those years, many ideas on how to disperse, collect, quantify, and analyze the mircrospheres used to study plume dispersion in the vineyard were tried and developed. This included the design of new equipment, the novel use of existing technologies, the improvement of ideas utilized by others, and the incremental improvement of all of these from year to year as campaigns continued. Among the methodologies was the use of inert, fluorescent mircospheres as a fungal spore analog, the invention of simple rotating-arm impaction traps mounted on low-profile aluminum masts that were deployed in large arrays, and the use of a fluorescence stereo microscope with specific excitation filters and imaging software for use in quantifying the microsphere concentrations. The impaction trap arrays and an array of microsphere release devices were operated using a wireless network, thus allowing for reconfiguration and simple redeployment. This also allowed for independent control for plumes emitted in different directions based on the wind direction. These techniques have enabled for incredibly detailed research into particle plume dynamics in a vineyard.