title: Space-Time Point Pattern Analysis of Flavescence Dorée Epidemic in a Grapevine Field: Disease Progression and Recovery.
abstract: Analyses of space-time statistical features of a flavescence dorée (FD) epidemic inVitis viniferaplants are presented. FD spread was surveyed from 2011 to 2015 in a vineyard of 17,500 m2surface area in the Piemonte region, Italy; count and position of symptomatic plants were used to test the hypothesis of epidemic Complete Spatial Randomness and isotropicity in the space-time static (year-by-year) point pattern measure. Space-time dynamic (year-to-year) point pattern analyses were applied to newly infected and recovered plants to highlight statistics of FD progression and regression over time. Results highlighted point patterns ranging from disperse (at small scales) to aggregated (at large scales) over the years, suggesting that the FD epidemic is characterized by multiscale properties that may depend on infection incidence, vector population, and flight behavior. Dynamic analyses showed moderate preferential progression and regression along rows. Nearly uniform distributions of direction and negative exponential distributions of distance of newly symptomatic and recovered plants relative to existing symptomatic plants highlighted features of vector mobility similar to Brownian motion. These evidences indicate that space-time epidemics modeling should include environmental setting (e.g., vineyard geometry and topography) to capture anisotropicity as well as statistical features of vector flight behavior, plant recovery and susceptibility, and plant mortality.
authors.affiliation: School of Civil Engineering, The University of Sydney, Sydney NSW, Australia.
authors.forename: Federico
authors.initials: F
authors.lastname: Maggi
authors.affiliation: Istituto per la Protezione Sostenibile delle Piante, Consiglio Nazionale delle RicercheTurin, Italy; Dipartimento di Scienze Agrarie, Forestali e Alimentari, Entomologia, Università degli Studi di TorinoTurin, Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: Bosco
authors.affiliation: Istituto per la Protezione Sostenibile delle Piante, Consiglio Nazionale delle Ricerche Turin, Italy.
authors.forename: Luciana
authors.initials: L
authors.lastname: Galetto
authors.affiliation: Istituto per la Protezione Sostenibile delle Piante, Consiglio Nazionale delle Ricerche Turin, Italy.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Palmano
authors.affiliation: Istituto per la Protezione Sostenibile delle Piante, Consiglio Nazionale delle Ricerche Turin, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Marzachì
keywords: Scaphoideus titanus; Vitis vinifera; flavescence dorée; pattern; randomness; space-time epidemics