First report of Fusarium redolens causing root rot disease of wheat and barley in Morocco

Field surveys carried out in wheat (durum and soft) and barley fields in April-May 2017 in North-West Morocco resulted in the isolation of a large number of fungal isolates from typical necrotic lesions characterizing the root rot of these cereals. Microscopic observations, based on morphological criteria linked an isolate of Fusarium oxysporum with an isolate of F. solani . Another Fusarium isolate ZF25, showed intermediate morphological characteristics between F. solani and F. oxysporum. Molecular comparisons showed the ZF25 and F. redolens to have a similarity of 99%. The sequence from this isolate was submitted to GenBank (accession number MT758201). Koch’s postulate was verified by inoculating these three isolates into varieties of wheat (hard and soft) and barley. All isolates induced necrotic lesions on the roots. Pathogen re-isolations from these lesions were positive. The percentages of the highest severity class S4 can reach 41.6% for wheat and 16.6% for barley. The percentages of incidences and indices of root rot observed in the wheat and barley plants inoculated with the three Fusarium isolates vary between 83.6 and 100% and between 58.3 and 70% respectively. These inoculation tests have shown that F. redolens has a strong pathogenicity towards wheat and barley. This species has not been reported in Morocco among the fungi associated with roots of barley and wheat and to our knowledge; this is the first report of this pathogen among the Fusarium complex responsible for root rot of these cereals.