Influence of seed treatment, temperature and origin of inocula on pathogenicity of Fusarium species to wheat and barley seedlings

In presented work, the influence of host and fungicide seed treatment on pathogenicity of 4 Fusarium species and M. nivale to wheat and barley seedlings were studied in “in vitro” conditions. The effect of Fusarium and M. nivale inoculation on coleoptile growth retardation (CGR) was analysed with respect to host and the origin of the isolates. Of F. culmorum, F. graminearum and F. poae , there is no significant influence of host (barley or wheat kernels) and isolates origin on pathogenicity of the species. Of M. nivale and F. avenaceum , the pathogenicity was significantly influenced by the host and isolates origin. F. avenaceum was more pathogenic to barley than M. nivale , on wheat opposite. The pathogenicity of tested species towards barley seeds (expressed as CGR) was assessed in downward order: F. culmorum, F. graminearum, F. avenaceum, M. nivale, F. poae . Of the wheat, the order was following: F. culmorum, F. graminearum, M. nivale, F. avenaceum, F. poae . The most aggressive pathogen towards both hosts was F. culmorum and F. graminearum . The weakest pathogen of both hosts was F. poae .The fungicide efficacy (FE) of all fungicides tested was decreased towards the species with higher pathogenicity. The higher FE in wheat than in barley was observed. The significant influence of isolates origin on FE was observed by M. nivale and F. graminearum only. The average FE of difenoconazole, tebuconazole and tebuconazole + thiram against certain Fusarium and M. nivale species decreased in following order: F. poae, F. culmorum, F. avenaceum, F. graminearum, M. nivale . The FE of quazatine was decreased as follows: F. avenaceum, F. poae, F. culmorum, F. graminearum, M. nivale . The FE of iprodione + triticonazole was estimated in downward order: F. poae, F. avenaceum, F. culmorum, M. nivale, F. graminearum . The FE of carboxin + thiram decreased in following order: F. poae, F. avenaceum, M. nivale, F. culmorum, F. graminearum . The results shoved great variation of FE depending on host and tested fungal species. There is no fungicide with universal and equal FE against all Fusarium species for seed treatment. The results highlighted the importance of selection of the most effective fungicide towards the prevalent pathogen in ecosystem or in seeds, based on laboratory myco-analysis.