Alternaria leaf spot of Safflower

The fungus Alternaria carthami, which causes leaf blight of safflower, was found to be seed borne. Although some seeds from which A. carthami was isolated were visually discoloured, it was also possible to isolate A. carthami from non-discoloured seeds. A. carthami isolated from seed produced typical leaf blight symptoms in glasshouse inoculations. The fungus reduced seed quality and caused pre-emergence death, seedling death and diseased seedlings. The importance of seedling infection by seed-borne A. carthami was demonstrated by the rapid build up of the disease in the field following the planting of infected seed. Relatively poor levels of control of seed-borne infection were achieved with fungicides when applied as a dust to the seed coat.