New Frontiers in the Study of Dispersal and Spatial Analysis of Epidemics Caused by Species in the GenusPhytophthora

Abstract

Diseases caused by species in the genus Phytophthora are responsible for significant economic losses on a wide range of host plants. Spatial pattern is one of the most characteristic ecological properties of a species, and reflects environmental and genetic heterogeneity and reproductive population growth acting on the processes of reproduction, dispersal, and mortality. Species of Phytophthora can be dispersed either in soil, via surface water movement down rows, from rain splash dispersal, by air, or via movement by humans or invertebrate activity. Dispersal results in patchiness in patterns of disease or inoculum in soil. In this chapter we discuss the mechanisms of dispersal of members of this important genus and describe several methods that can be used to statistically analyze data for which spatial coordinates are known. The methods include testing spatial autocorrelation for binary data or continuous data, semivariograms, and regression models for spatial data. The goal of spatial pattern analysis is to gain an understanding of the mechanisms of dispersal of propagules and to sort out the physical and biological factors that are important for spread of plant pathogens and ultimately, for disease management.

Characterizing spatial–temporal tree mortality patterns associated with a new forest disease

“…In studying plant disease epidemics, quantifying and understanding the spatial pattern of disease establishment and spread is fundamental to understand disease dynamics because spatial pattern reflects the environmental forces acting on the dispersal and life cycles of a pathogen (Ristaino and Gumpertz, 2000;Suzuki et al, 2003). For this reason, and because plant diseases can operate at large spatial scales, researchers are increasingly using landscape approaches (e.g.…”

Effect of prior tillage and soil fertility amendments on dispersal of Phytophthora capsici and infection of pepper

“…A variety of cultural practices are recommended to reduce the incidence of disease (Hausbeck and Lamour 2004;Ristaino and Johnston 1999). Disease spread within a cropping season can be greatly reduced by planting into stubble from a no-till wheat or rye-vetch cover crop Ristaino and Gumpertz 2000). However, yield is often compromised in the no-till planting of pepper .…”

Spatial and temporal analysis of coffee wilt disease caused by Fusarium xylarioides in Coffea canephora

“…The study of spatial and temporal patterns can provide quantitative information on population dynamics, aid in the design of epidemiological studies, sampling programmes for disease or pathogen monitoring, and be used to generate hypotheses about underlying ecological processes (Ristaino and Gumpertz 2000). Among others, semi-variance (variogram) analyses are used in the study of spatial-temporal dynamics of different plant diseases (Rekah et al 1999;Van de Lande and Zadoks 1999;Jaime-Garcia et al 2001).…”