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Remarks (public):For a complete description including images see 
Remarks (internal):Septoria tritici attacks leaves, stems, leaf sheaths and internodes, ears being unaffected or rarely slightly infected (57, 3416, 65, 2273). Symptoms include hastened senescence of leaves, delayed expansion of leaves during spring and reduction of leaf size in some later formed leaves (65, 4856). The disease is favoured by cool weather with prolonged precipitation. These conditions may lead to localized epiphytotics in winter wheat in Argentina, New Zealand and the USA (38, 687; 44, 1837d). Severe attacks in Denmark even in flag leaf were related to high rainfall in April-May (64, 2459). In winter wheat it is known to reduce yields by 18% (65, 4857). The disease develops from lower to upper leaves with pycnidia forming on both surfaces of the leaf. On seedlings leaf spots are usually wide and oval, but on the mature plant they are elongated (57, 3416). The disease may disappear on the arrival of warm drier weather in summer (27, 349). The fungus is present in wheat stubble and ascospores are discharged following periods of wetness caused by rain or dew. The main ascospore discharge occurs in late autumn to early spring in Australia (58, 3242). Conidia germinate most frequently near or on stomata! cells and the germ tubes penetrate through the stomata (61, 1130). Conidial sporulation and inoculum production from wheat are best in Czapek agar; mycelial growth on oat meal agar. Cardinal temps for growth are: min. 1°C, opt. 24°C and max. 33°C (59, 5080). Ascospores are the main source of primary inoculum in Australia and New Zealand (58, 3242), while primary mycelium has been reported as the main source of inoculum in Tunisia (57, 2486). Infected plant debris may also act as a source of inoculum (55, 3524). Septoria tritici can also infect other grasses, which may serve as alternate hosts for the fungus (54, 5391; 55, 4021; 58, 3242). Varietal differences in susceptibility have been recorded, and selection undertaken (38, 687; 41, 298; 43, 2590; 44, 672; 51, 3941; 60, 4388). Late-maturing cultivars are attacked less than early-maturing ones, and yield is positively correlated with the length of the growing period (60, 4388). Cultural methods of control include the removal of volunteer wheat, and destruction of straw and stubble of infected crops, deep ploughing or burning (38, 687), and the use of balanced fertilizers to counter-act excessive N, which favours infection (43, 1610; 44, 672). Seed treatments and fungicidal applications have also been effective in controlling the disease (61, 4793, 4804; 62, 618; 63, 533, 2827; 65, 1196, 1816).
Description type:Non-original description 
Description:Mycosphaerella graminicola (Fuckel) Schroeter, in Cohn, Krypt.-Fl. Schles. 3: 340, 1894.
Sphaerella graminicola Fuckel, Jahrb. Nassau Ver. Nat. 23-24: 101, 1870.
Anamorph: Septoria tritici Rot., in Desm., Ann. Sci. nat. Bot. ser. 2 17: 107, 1842.
Ascomata dark brown, immersed, scattered, rounded to oval in surface view, 80-150 µm diam., ostiolate with a pseudoparenchymatous wall. Asci oblong to obpyriform, bitunicate, thick-walled, 8-spored, 30-40 (-55) x 11-44 (-20) µm. Ascospores colourless, elliptical, 1-septate in the middle or below and with one cell slightly longer and broader than the other, 9-16 (-18) x 2,5-4,5 µm. Conidiomata pycnidial, globose to elliptical, brown to black, amphigenous, mostly aggregated and arranged longitudinally between veins, 90-180 µm diam., ostiolate with a hard pseudoparenchymatous wall. Conidiogenouscells colourless, simple, obpyriform, holoblastic, arising from the innermost layer of cells lining the pycnidial cavity. Conidiacolourless, straight to flexuous, obtuse at the base, gradually tapering to an acute apex, (2-) 3- septate, 30-80 x 1,5-2 µm.
Hosts: Lolium perenne, Secale vulgare, Triticale, Triticum spp.
Disease: Leaf spot or speckled leaf blotch of wheat.
Geographical distribution: Africa: Algeria, Angola, Ethiopia, Kenya, Morocco, South Africa, Tanzania. Asia: Afghanistan, China, Cyprus, India, Iran, Iraq, Israel, Japan, Korea, Lebanon, Pakistan, Saudi Arabia, ?Syria (66, 2306), Tunisia, Turkey, USSR. Australasia & Oceania: Australia, New Zealand. Europe: Austria, Belgium, Bulgaria, Czechoslovakia, Denmark, France, Germany, Great Britain, Greece, Hungary, Italy, Netherlands, Norway, Poland, Portugal, Rumania, Spain, Sweden, Switzerland, USSR, Yugoslavia. North America: Canada, Mexico, USA. Central America: El Salvador, Guatemala. South America: Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Uruguay (CMI Distribution Map 397, ed. 3, 1986).
Physiological specialization: Races have been reported from Israel (53, 1768), Morocco (66, 3747), USA (2, 211; 37, 32) and Yugoslavia (45, 1349).
Transmission: By windborne ascospores and conidia, by infected plant debris and seeds (38, 687; 42, 11; 55, 3524; 57, 2486).
Literature: Brown, Australian Plant Pathology Newsletter 4: 37, 1975; Brown, Kellock & Paddick, Australian Journal of Agricultural Research 29: 1139-1145, 1978; Brown & Rosielle, Journal of Agriculture 21: 8-11, 1980; Hilu & Bever, Phytopathology 47: 474-480, 1957; Holton, Plant Disease Reporter 49: 242-243, 1965; Sewell & Caldwell, Phytopathology 50: 654, 1960; Shaw, Proceedings of the Linnean Society, New South Wales 78: 122- 130, 1953; Shipton, Boyd, Rosielle & Shearer, Botanical Review 37: 231-262, 1971.

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