Incidence of seed infection in finger millet and sunflower collected from Dodoma, Iringa and Morogoro regions

Abstract

Surveys were conducted to assess the incidence of seed borne pathogens on fingermillet (Eleusine coracana (L.) Gaetrn) and sunflower (Helianthus annus L.) in seeds produced by farmers in Morogoro Rural, Kilosa districts (Morogoro Region), Kondoa, Dodoma Rural districts (Dodoma Region), and Njombe and Iringa Rural districts (Iringa Region), in Tanzania. A total of 72 seed samples were collected and taken to the laboratory for assay of seed-borne pathogens. The blotter method was used to detect fungal pathogens and identification was done based on colony morphology, characteristics of fruiting bodies and spores observed under the stereo and compound microscopes. Seed-borne bacterial pathogens were detected using the direct plating method and identified based on pigmentation, biochemical tests, carbon source utilization, and hypersensitive reaction (HR), as well as pathogenicity tests. Three fungal pathogens (Pyricularia grisea, Bipolaris setariae and B. nodulosa) were detected in fingermillet seed samples. The level of seed infection ranged from 10 to 50%. Pyricularia grisea was more prevalent in most fingermillet seed samples tested. Only two fungal pathogens (Altenaria altenata and Verticillium albo-artum) were detected on most of the sunflower seed samples tested. Bacterial pathogens detected on fingermillet seed included Pseudomonas eleusines, Xanthomonas campestris pv corocanae, Pseudomonas syringae pv syringae and P. andropogonis. The pathogens Erwinia caratovora subsp caratovora, P. marginalis pv marginalis, P. syringae pv tagetis, P. syringae pv helianthi and P. syringae pv aptata were detected on sunflower seed samples. Pseudomonas andropogonis (causing bacterial stripe), was detected on fingermillet in samples collected from Ilonga Kilosa, Zanka Dodoma Rural district, Kinonko and Mikese Market in Morogoro Rural district. The result of this study hasiii also established very important information on the occurrence of fingermillet blast (P. grisea) and bacterial stripe (P. andropogonis) across the surveyed regions. This is the first report of P. andropogonis on fingermillet in Tanzania.