Defining Soilborne Pathogen Complexes Provides a New Foundation for the Effective Management of Faba Bean Root Diseases in Ethiopia.

Soilborne diseases cause losses of 45-70% in faba bean in Ethiopia. Studies were undertaken to define soilborne pathogens and their complexes in Ethiopia. First, the severity of root rot was assessed in 150 field sites across seven Ethiopian regions. Soil samples were collected, and the DNA of 29 pests and pathogens was quantified using a commercial quantitative PCR (qPCR) soil testing service. There was a very high incidence rate of , as well as clades F and I. The other detected species in order of incidence included , , , , and , and as well as low levels of Five anastomosis groups (AG) of , namely AG2.1, AG2.2, AG3, AG4, and AG5, were detected, of which AG2.2 and AG4 were most prevalent. We believe this is the first report of occurrence for Ethiopia of , , and the five AGs for . There were very high incidence rates of the foliar pathogens , , and and of the nematode followed by and . The root rot severity and distribution varied significantly across regions, as well as with soil types, soil pH, and soil drainage. Subsequently, metabarcoding of the soil DNA was undertaken using three primer pairs targeting fungi (ITS2), species (TEF1 α), and Oomycetes (ITS1Oo). The ITS2 and TEF1α primers emphasized as the most abundant soilborne fungal pathogen and highlighted , , , , , , , , , , and as first reports of occurrence for Ethiopia. The ITS1Oo primer confirmed spp. as the most prevalent of all Oomycetes.