Identification and Pathogenicity of Fungal Pathogens Causing Black Point in Wheat on the North China Plain

Fungi associated with black point were isolated from three highly susceptible wheat genotypes in the North China Plain. The 21 isolates represented 11 fungal genera. The most prevalent genera were Alternaria (isolation frequency of 56.7%), Bipolaris (16.1%), and Fusarium (6.0%). The other eight genera were Curvularia, Aspergillus, Cladosporium, Exserohilum, Epicoccum, Nigrospora, Penicillium, and Ulocladium; their isolation frequencies ranged from 0.8 to 4.8%. The pathogenicity of the isolates was individually assessed in the greenhouse by inoculating wheat plants with spore suspensions. Ten of the 21 isolates caused significantly higher incidences of black point than that the controls. These isolates belonged to eight fungal species (A. alternata, B. sorokiniana, B. crotonis, B. cynodontis, C. spicifera, F. equiseti, E. rostratum, and E. sorghinum) based on morphological traits and phylogenetic analysis. The average incidences of black point in the eight fungal species were 32.4, 54.3, 43.0, 41.9, 37.2, 38.8, 50.1, and 34.1%, respectively. B. sorokiniana and A. alternata were determined to be the most important pathogens in the North China Plain based on fungal prevalence and symptom severity. This study is the first to identify E. rostratum as a major pathogen causing black point in wheat.