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POSTERS: Population biology and genetics

Pythium Pathogens of Common Bean in North Dakota and Minnesota
Rachael Poore - North Dakota State University. Julie Pasche- Dept of Plant Pathology, North Dakota State University, Kim Zitnick-Anderson- North Dakota State University

North Dakota and Minnesota rank number one and four in US common bean (Phaseolus vulgaris L.) production, respectively. Root rot is a destructive disease to common bean production worldwide. To effectively manage root rot, it is vital to know what pathogens are most damaging. Pythium spp., Fusarium spp., and Rhizoctonia solani Kühn are known to cause devastating root rot in common beans. A root rot survey conducted a decade ago established Fusarium and Rhizoctonia pathogen populations in the region. However, Pythium spp. were not included in the survey. Metalaxyl (mefenoxam) is commonly used as seed treatments to manage Pythium spp. in many crops. Metalaxyl resistance has been observed in some Pythium populations in the US in numerous crops. To date, metalaxyl resistant Pythium spp. have not been observed associated with common beans. The objectives of this research are to establish which Pythium species are important pathogens in common beans in this region by determining the pathogenicity and aggressiveness of isolates collected and to evaluate metalaxyl sensitivity in the Pythium population. To date, 16 Pythium spp. have been morphologically identified from 13 of 33 fields sampled in 2018. Preliminary results indicate that varying levels of aggressiveness exist among the Pythium spp. isolated. Metalaxyl sensitivity levels for the Pythium spp. identified also will be reported.