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Remarks (internal):Helminthosporium solani is the cause of silver-scurf (tache argentée) of potato tubers. Ellis (Mycol. Papers 82: 1-55. 1961) showed that H. solani, described originally on stems of Solanum nigrum from Algeria provided the earliest epithet for the silver-scurf fungus which had been known for many years as Spondylocladium atrovirens. Ellis (op. cit.) redescribed and illustrated the fungus and recorded it not only on S. tuberosum but also on S. dulcamara, Citrus limetta and Leucaena glauca.
Conners (Annotated Index of Plant Diseases in Canada. Canada Dept. Agric. Publ. 1251. 1967) recorded this fungus from coast to coast; a record of the fungus from Newfoundland was published in Canadian Plant Disease Survey 44(1): 34. 1964. An annotated account of H. solani is given in C.M.I. Descriptions of Pathogenic Fungi and Bacteria, No. 166 and its global distribution is documented in C.M.I. Map No. 233 (Ed.2).
Description type:Non-original description 
Description:Helminthosporium solani Durieu & Montagne in Durieu, Fiore d'Algérie, Cryptogamie, p. 356. 1849.
= Brachysporium solani (Dur. & Mont.) Sacc., Syll. Fung., 4: 428. 1886.
= Dematium atrovirens Harz, Bull. Soc. Nat. Moscow, 44: 129. 1871.
= Spondylocladium atrovirens (Harz) Harz in Sacc., Syll. Fung., 4: 483. 1886.
= Helminthosporium atrovirens (Harz) Mason & Hughes in Hughes, Can. J. Bot., 31: 631. 1953.
= Cladosporium abietinum Zukal, Verh. der K.K. zool.-bot. Ges. Wien, 37: 44. 1887.
Colonies dark brown to black, hairy. Mycelium mostly immersed, partly superficial, composed of branched, septate, subhyaline to brown, mostly smooth, sometimes roughened hyphae 1.5-5.4 µm wide. Stromata absent or rudimentary and mostly immersed or partly superficial and up to 80 µm wide. Conidiophores scattered and produced singly, terminally and laterally on the hyphae or in groups of up to 10 on stromata. They are simple, straight or flexuous, 135-700 µm long and 6.3-9 µm wide above the basal cell which may be swollen up to 10-12 µm: conidiophores are more or less cylindrical, tapering gradually toward the rounded apex which is 5.7-7.2 µm wide. They are septate at 15-45 µm intervals, brown to dark brown and thick-walled at the base, pale brown and slightly thinner-walled at the apex. `Pores' in the wall toward the distal end of the conidiophore indicate the position at which solitary, readily seceding conidia have developed. The apical cell of the conidiophore bears up to six pores and (1-)2 to 4 similar pores below the septa or distally scattered in the wall of 4 to 19 cells below the apical one. Conidia obclavate, straight or curved, smooth, subhyaline to brown, paler toward the apex and brown to dark brown at the basal scar. The lateral wall is up to 2.8 µm thick in the broader part of the conidium but thinner toward the apex. They are 3- to 9-pseudoseptate with the lumen usually angular in outline. Conidia measure 25-61(-90) x 7.4-10.8 µm and 3-4 µm wide at the apex.
Substrate: Tubers of Solanum tuberosum.
Distribution: Newfoundland, Nova Scotia, Ontario, Manitoba
Taxon name: