Current status of sunflower leaf blight caused by alternaria helianthi in Iramba and Handeni Dstricts in Tanzania
| dc.contributor.author | Chirimi, Stella Gamaliel | |
| dc.date.accessioned | 2026-08-28T05:36:57Z | |
| dc.date.available | 2026-08-28T05:36:57Z | |
| dc.date.issued | 2013 | |
| dc.description | Dissertation | |
| dc.description.abstract | Surveys were conducted to investigate the incidence and severity of Alternaria blight disease caused by Alternaria helianthi in Iramba and Handeni districts. A total of 30 seed samples collected from farmers were tested for infection by A. helianthi and other fungi using the Blotter method. Identification of fungi was based on morphological characteristics observed under the stereo and compound microscopes and confirmed by pathogenicity tests done in the screen house. Screen house and field data were analyzed using SAS 2004 and SPSS computer package and mean separation was done by Duncan Multiple Range Test at < 0.05. Results showed that sunflower seed samples were infected by A. alternata (47.75 %), F. palidoroseuni (16.25 %), F. moniliforme (12.0 %), M. phaseolina (3.75 %), and A. helianthi (3.75 %). Seed infection by A. helianthi was lower than that of other seed-bome pathogens. However, it was associated with the highest disease incidence (22.7 %) compared to A. alternata (13.5 %) and Fusarium species (1.5 %), under field conditions. Such results implied that low seed infection by A. helianthi can result into high disease incidences under field conditions. The results also showed that A. helianthi can be categorized into two groups based on their morphology. The first group had large radial growth, gray mycelia colour and smooth margin and the second group had grayish black appearance and irregular margins on VS agar medium, implying variations of A. helianthi. The results also showed that most of the fanners (70 %) in the study areas were unaware of the disease and 76.7 % of fanners did not apply any control measure for Alternaria blight disease. Future studies should therefore, focus on factors that influence high level of disease incidences and severity in the field compared to low level of seed infection. Further studies on the genetic variation between the two groups of A. helianthi are also needed. Training of the farmers on identification of ' Alternaria blight disease is of importance for early disease management. | |
| dc.description.sponsorship | The Agricultural Sector Development programme (ASDP) | |
| dc.identifier.uri | https://www.suaire.sua.ac.tz/handle/20.500.14820/7934 | |
| dc.language.iso | en | |
| dc.publisher | Sokoine University of Agriculture | |
| dc.subject | Sunflower | |
| dc.subject | Tanzania | |
| dc.subject | Iramba Dstricts | |
| dc.subject | Alternaria blight disease | |
| dc.subject | Alternaria helianthi | |
| dc.title | Current status of sunflower leaf blight caused by alternaria helianthi in Iramba and Handeni Dstricts in Tanzania | |
| dc.type | Thesis |