Septoria lycopersici. [Descriptions of Fungi and Bacteria].
Abstract A description is provided for Septoria lycopersici. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Lycopersicon esculentum. Also on Datura stramonium, Solanum carolinense, S. nigrum and S. melongena. Other species of Lycopersicon and Solanum tuberosum have been reported susceptible on inoculation (MacNeill, 1950). DISEASE: Leaf spot of tomato. Lesions abundant, amphigenous, circular to irregular, rarely confluent, often vein-limited and depressed, water-soaked, becoming pale brown and later grey with dark margins, up to 2 mm. diam. All stages of growth of the plant may be attacked. Severe infection causes leaves to shrivel and produces premature defoliation, exposing the fruit to sun-scald. GEOGRAPHICAL DISTRIBUTION: World-wide on tomato (CMI Map 108, ed. 3, 1959). TRANSMISSION: Spores are disseminated by rain-splash and wind-blown water, and may also be carried on the hands and clothing of fruit-pickers or by insects (chiefly beetles) (Martin, 1918; 20: 183). The fungus is not a soil inhabitant but may persist in a viable condition from one season to the next on debris of diseased plants incorporated in the soil (3: 615; 20: 181). Solanaceous weeds also serve as one of the main means of overwintering the pathogen (3: 615). Seed contaminated with spores can produce infected seedlings (20: 183) but there is some doubt whether the pathogen is truly seed-borne (32: 154; 43, 3324; Noble et al, 1958).