Pathogenicity of nine Fusarium species causing head blight and crown rot in Iraqi wheat cropping system, Basra province

Abstract

This experiment was conducted to determine pathogenicity of 32 isolates of nine Fusarium spp. (F. chlamydosorum, F. equiseti, F. graminearum, F. pseudograminearum, F. solani, F. avenaceum, F. culmorum, F. cerealis and F. nygamai) on the heads, stems and seeds of soft winter wheat cultivar, Abu Ghraib 3 (AG 3). For pathogenicity test on head bleaching, the effects of disease severity and percent Fusarium head blight (FHB) were significant (P ≤ 0.05) for each of Fusarium species and isolates as well as time were analyzed individually. Analysis by Fusarium species displayed that F. culmorum, F. cerealis and F. graminearum caused the highest percent FHB at 21 days after inoculation, while F. chlamydosporum and F. nygamai were the least pathogenic. F. Pseudograminearum had the greatest effect on seed germination (40-48%), followed by F. culmorum (53-60%). The effects of most examined Fusarium species and isolates were significant (P ≤ 0.05) for discoloration rating of basal stem as indications of Fusarium crown rot (FCR). F. pseudograminearum had the highest average percent disease severity of FCR (60.58%), followed by F. cerealis (51.13%), F. culmorum (49.58%), F. avenaceum (48.61%) and F. graminearum (43.92%). Infected heads and seeds might be resulted in basal stem infections, consequently serving Fusarium inoculum to be survived over time. Infected ground and underground plant parts could then become an inoculum sources for head infection in the next seasons.