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Modeling the spatial spread of alfalfa stem nematodes

Abstract:

The velocity of a traveling invasive front of a pest can be determined through the moment generating function associated to the so-called contact distribution of the dispersal process. This distribution captures the non-local character of the underlying spatial component in an invasion event. In this paper we present a spatial model for the spread of alfalfa stem nematodes, using a Gaussian contact distribution, parameterized by experimental data. With this we proceed to approximate the velocity of nematode invasive fronts in the absence of advection, i.e. without nematode transport through flood irrigation. The parameterized probability kernel is then used to calculate the front velocities when resistant varieties of alfalfa are introduced. We found that, unsurprisingly, invasive velocities are relatively low and cannot support the rapid dispersal of the disease among fields as seen in practice. This result leads to the conjecture that changing current irrigation practices, from flood to sprinkle irrigation, could effectively contribute to controlling the spread of alfalfa stem nematodes.