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Remarks (public):For a complete description including images see www.cababstractsplus.org/dfb 
Remarks (internal):It is a serious disease in India (54, 954), Zambia (43, 531), Brazil (51, 2751), Romania (54, 5035) and Tanzania (56, 3656). The pathogen has 2 collateral hosts (56, 3656). Plants are susceptible at all stages of their growth (Anilkumar et al., 1974). It is pathogenic and on inoculation with conidial suspension to one month old plants, symptoms appeared after 48 hours (Anilkumar et al., 1974). Although Tubaki & Nishihara (1969) report that conidia are not in chains, Mukewar et al. (1974) observed 2-3 conidia in chains on the host and in culture. Work on chemical control measures and a search for resistant varieties are in progress. Russian Giant variety is somewhat resistant (43, 531).
 
Description type:Non-original description 
Description:Alternaria helianthi (Hansf.) Tubaki & Nishihara, Transactions of the British Mycological Society 53: 147, 1969.
Helminthosporium helianthi Hansford, 1943.
Helminthosporium helianthi Pavgi, 1964.
Mycelium olivaceous brown, septate, smooth, branched, 2,5-5 µm wide, intercellular in mesophyll cells. Conidiophores cylindrical, solitary or in fascicles, simple, straight or slightly flexuous, sometimes geniculate, pale to mid olivaceous brown, smooth, septate, up to 120 µm long, 8-11 µm wide. Conidia mostly solitary but occasionally in chains of two, straight, sometimes curved, cylindrical or obclavate, rounded at the ends, subhyaline to mid pale olivaceous brown or golden brown, smooth, with 2-12 transverse septa and occasionally 1 or more longitudinal or oblique septa, often constricted at the septa, 45-145 x 10-30 µm. Colonies on potato dextrose agar growing slowly but sporulating well, effuse, thinly hairy and grey with entire margin.
Hosts: On Helianthus annuus, H. argophyllus, H. debilis.
Disease: Leaf spots, stem breaking, blossom blight or head blight. Spots are found on leaves, stems, petioles, sepals or petals. They are dark brown with pale margin and yellow halo and then become irregular by coalescing, leading to blight and defoliation and death of the plant (Tubaki & Nishihara, 1969; Anilkumar et al., 1974). Stem breaking is also common (43, 531).
Geographical distribution: Africa (Malawi, Rhodesia, Tanzania, Uganda, Zambia); Asia (Burma, India, Japan);
Australia (Queensland); Europe (Romania, Yugoslavia); South America (Argentina, Brazil).
Physiologic specialization: None reported.
Transmission: The fungus possibly survives in crop debris and in damp weather conidia are produced which are
disseminated by rain and wind. Seed transmission also is possible as the seeds are infected (Anilkumar et al., 1974).
Literature: Anilkumar, Urs, Seshadri and Hedge, Current Science 43: 93, 1974; Mukewar, Lambat, Nath, Majumdar, Rani & Chandra, Current Science 43: 346, 1974; Tubaki & Nishihara, Transactions of the British Mycological Society 53: 147, 1969.
 
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