Distribution and abundance of Aphanomyces euteiches in agricultural soils: effect of land use type, soil properties, and crop management practices
Citation
Karppinen, E.M., Payment, J., Chatterton, S., Bainard, J.D., Hubbard, M., Gan, Y., Bainard, L.D. (2020). Distribution and abundance of Aphanomyces euteiches in agricultural soils: effect of land use type, soil properties, and crop management practices. Applied Soil Ecology, [online] 150 http://dx.doi.org/10.1016/j.apsoil.2019.103470
Plain language summary
Aphanomyces euteiches is a soil-borne pathogen that causes root rot in agronomically important pulse crops such as field pea and lentil. The soil pathogen was not reported in western Canada until 2012. However, A. euteiches has a global distribution and has been documented in regions with close proximity to western Canada. In this study, we used a large scale survey across the major agricultural regions and soil types of Saskatchewan, including native rangeland that has never been broken, to gain a better understanding of the distribution and abundance of A. euteiches. Despite its recent discovery in Saskatchewan, this study demonstrated that A. euteiches is widespread across the province, land use and soil types, and supports the hypothesis that A. euteiches was present prior to its discovery in 2012. In addition, the frequent detection in native rangeland soil indicates that A. euteiches is likely indigenous to this region. The more frequent use of field pea and lentil crops combined with higher than average levels of precipitation in the region have likely increased inoculum levels in annually cropped field soils. Overall, this study highlights that pulse crop root rot issues will persist or expand in the future due to the widespread distribution of this pathogen throughout the agricultural regions in Saskatchewan.
Abstract
Aphanomyces euteiches is a soil-borne pathogen that causes root rot in susceptible pulse crops. Although widespread across Canada, A. euteiches was not reported in Saskatchewan until 2012. The distribution of this pathogen across the Canadian prairies is unknown and it is unclear whether it is native to the region. The objective of this study was to conduct a survey of A. euteiches across the major agricultural soils of Saskatchewan, Canada to determine its distribution and to assess the relative importance of factors related to its distribution and possible spread across the province. Soil samples were collected from lentil and pea fields and their associated roadside ditches, as well as from native and tame rangelands. Soil samples were analyzed using a quantitative polymerase chain reaction (qPCR) assay to detect and quantify the presence of A. euteiches. In addition, root rot severity was assessed on affected pea and lentil plants, and the physical and chemical properties of the soils were measured. A. euteiches was present across all land use (i.e., annual cropland, roadside ditches, and rangeland) and soil types in Saskatchewan. A. euteiches abundance was highest in samples collected from annually cropped fields. Within annual cropland, A. euteiches abundance was higher in pea fields than lentil fields. Soil moisture, total and organic carbon, and total nitrogen were positively correlated to A. euteiches abundance in field and roadside soils. Based on this survey, A. euteiches is wide-spread across all the major agricultural regions of Saskatchewan and is not limited to specific soil or land use types. The frequent detection of A. euteiches in native rangeland indicates it is likely native to Saskatchewan. The significant relationship between A. euteiches gene abundance and disease severity in pea fields indicates that the qPCR assay may be a useful indicator for predicting the potential for certain agricultural soils to cause A. euteiches root rot in pea crops.