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Research Project: Biology, Ecology, and Genomics of Pathogenic and Beneficial Microorganisms of Wheat, Barley, and Biofuel Brassicas

Location: Wheat Health, Genetics, and Quality Research

Title: Population dynamics of root pathogens of wheat under different tillage systems in NE Oregon

item YIN, CHUNTAO - Washington State University
item MCLAUGHLIN, KATHERINE - Oregon State University
item Paulitz, Timothy
item KROESE, DUNCAN - Oregon State University
item HAGERTY, CHRISTINA - Oregon State University

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/2020
Publication Date: 7/1/2020
Publication URL:
Citation: Yin, C., McLaughlin, K., Paulitz, T.C., Kroese, D.R., Hagerty, C.H. 2020. Population dynamics of root pathogens of wheat under different tillage systems in NE Oregon. Plant Disease.

Interpretive Summary: Soilborne root pathogens of dryland wheat are a major constraint to yield in NE Oregon. Many growers are adopting reduced tillage or no-till to improve soil health. In this study, we surveyed the populations of 3 of the major fungal pathogens- Fusarium, Pythium and Rhizoctonia across NE Oregon. The first year, we used traditional soil dilution plating, and the 2nd year quantitative PCR techniques, which can quantify individual species based on the DNA. There was not a strong effect of tillage, but some pathogens such as Pythium ultimum were more abundant in areas with higher precipitation, and some like Rhizoctonia solani AG8 were more predominant in drier areas.

Technical Abstract: No-till or direct-seeding can be described as seeding directly into the crop stubble from the previous season without use of tillage. A reduction in tillage can result in many benefits, including increased soil organic matter, increased water holding capacity, and reduced fuel costs. However, the effect of no-till and reduced tillage on crop root disease profiles is poorly understood. To study the effect of tillage on disease dynamics, soil samples were collected from commercial wheat fields representing a wide range of tillage strategies in fall 2016 and fall 2017. Because precipitation might affect soil-borne diseases, wheat fields located across a diverse gradient of precipitation zones of the dryland Pacific Northwest were selected. Fusarium spp., Pythium spp., and Rhizoctonia spp. were quantified from soil samples using soil dilution plating and quantitative PCR (qPCR) assays. Results of dilution plating showed that the colony counts of Fusarium, Pythium, and Rhizoctonia at the genus level were negatively associated with tillage. However, the same patterns were not observed when specific causal agents of Fusarium, Pythium, and Rhizoctonia that are known to be pathogenic on wheat were quantified with qPCR. Furthermore, precipitation affected the population density of some fungal pathogens (F. culmorum, P. ultimum, and R. solani AG-8). Results of this study indicate that the benefits of adopting reduced tillage likely outweigh potential risk for increased root disease.