Print PagePlant virus diseases seriously impact agricultural production both in terms of yield and quality. Pulse crop production systems in the Inland Pacific Northwest region of North America are often constrained by two particular viruses: Pea enation mosaic virus and Bean leaf roll virus. These viruses require an insect vector to transmit between host plants. The optimal vector of these viruses is the pea aphid Acyrthosiphon pisum. Subsequently, the spread of virus disease is related to the population dynamics of the aphid vector. Traditional management of this crop-pathosystem has relied on efforts to control the aphid population. This strategy has been suboptimal because the disease process is variable and unpredictable.
In 2007 a project was undertaken to monitor the pea aphid population and map the prevalence of disease on the landscape. A geo-referenced network of sampling sites was established to monitor the spatial and temporal patterns of vector and disease. Spatial statistical approaches were used to map and model the disease process to generate more spatially explicit assessments of risk.
Results/Conclusions
The pattern of disease prevalence on the landscape is not stationary and inconsistent with the null hypothesis of constant risk. The location of a field appears to be a risk factor. Sub-regions in the southern latitudes of the study area exhibited higher than expected counts of disease occurrence under the null model. These regions are on average exposed to the earliest arrival of aphid vectors on the landscape. These findings are being incorporated into a decision support system being made available to pulse growers throughout the region. This study emphasizes the need to increase our understanding of the epidemiology of crop-pathosystems in order to devise effective management strategies that diminish disease impact and reduce the ecological costs of overuse of chemical controls.
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