P-178 - Root rot pathogens of pulse crops in Montana and associations with soil properties

Root disease is a major limitation to the yield and sustainability of Montana dry pea and lentil production. Issues have only worsened with time, as the soilborne pathogen structures that lead to root disease are able to build up in the rhizosphere. A complex of species can contribute to pulse crop root rot. These include Aphanomyces euteiches, Fusarium redolens, F. solani, F. avenaceum, F. oxysporum, Pythium spp., and nematodes. The difficulty with management is due to long-term pathogen survival, limited or no fungicide options, and broad host ranges for some pathogen species. Fifty-five dry pea and lentil fields were soil sampled from three to five sites. One site was a healthy control, with no root rot symptoms, and the rest showed evidence of root disease such as root browning, root thinning, lesions at the seed attachment, water-soaked roots, above-ground yellowing, stunting, and dying or dead plants. Soil was used for greenhouse bioassays, qPCR analysis, and testing of soil chemical and physical properties. Thirty percent of fields sampled had at least one site with severe root rot on dry pea and lentil in the greenhouse bioassays. Molecular analysis revealed that pathogen fungal and oomycete DNA was not limited to field sites displaying root rot symptoms. Soil factors associated with root rot severity include soil pH, organic matter, soil texture, and soil moisture of collected samples. This work contributes to the prediction of pulse crop root rots and provides information to help inform future management strategies and disease resistance breeding goals.