Incidence of Common Bunt (Tilletia spp.) in Syria

Field surveys were carried out in main wheat growing governorates during 2005 and 2006, covering major wheat growing areas in several Syrian provinces. Wheat fields were randomly observed and data relative to disease incidence recorded. Results showed that common bunt (Tilletia spp.) occurred in all wheat fields surveyed, but low variations in disease incidence were recorded. The highest rate was shown in the first year in Idleb province, while the lowest rate appeared in Daraa province. In the second year, the incidence was recorded in Aleppo and Hassakeh provinces. Results showed that causal agents of common bunt disease were both T .carries and T. foetida, with different proportions depending upon crop species and field geographical site. The frequencies of T. caries: T. foetida teliospores were 89.6: 10.4 in durum wheat and 6.3: 93.7 in bread wheat. Pathogenicity of 29 combinations (1:1w) of different Syrian isolates of pathogen species was tested against four durum wheat (Triticum durum) and four bread wheat (Triticum aestivum) lines which differ in reaction to the disease. A slight difference in spikes infection rate (SIR) was observed among the tested combinations, where SIR varied between 0 and 56% in durum and between 0 and 80% in bread wheat lines. The collected combinations during 2005 are divided according to their pathogenicity into three groups: Group I= weakly virulent: includes 9 combinations, Group II= moderately virulent: includes 13 combinations and Group III= highly virulent: includes 7 combinations