A Spatiotemporal Analysis and Dispersal Patterns of the Potato Cyst Nematode, Globodera pallida , in Idaho.

The potato cyst nematode, Globodera pallida, is a globally regulated potato pest. Detected in the U.S. in the state of Idaho in 2006, the infestation, as of February 2019, is limited to 1,326 hectares. Globodera pallida is an obligate sedentary endoparasite that reduces yields up to 80% and is spread through movement of soil, tubers or equipment. The objectives of this study were to describe the spatiotemporal pattern of G. pallida in infested fields and to model its dispersal patterns in Idaho. We used geostatistical tools and simulation models for mapping and description of the relationships between G. pallida incidence and spatial configurations. We found that the nematode is spatially clustered, prevalent around field edges, and its dispersal pattern followed the direction of cultivation. The absence of potato in an infested field significantly reduced the number of cysts sampled each year subsequent to the initial delimitation sampling in 2007. Phytosanitary measures prohibiting potato contributed in stopping nematode reproduction, and the use of chemical fumigants and biofumigant cover crops contributed to a significant reduction in egg viability. We observed a process of a non-linear decline in the prevalence of cysts as the distance separation from the primary infestation focus increased. A power-law model was used to fit G. pallida dispersal capabilities. This study contributed in describing G. pallida infestation for Idaho and provided information on the spatial pattern and landscape ecology of G. pallida in Idaho to facilitate common understandings on the challenges and opportunities for controlling this pest in Idaho.