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United States Department of Agriculture

Agricultural Research Service

Pearl Millet Diseases: Questionable and Poorly Described Diseases: Smut

Pearl Millet Diseases
Questionable and Poorly Described Diseases

Smut

Information on smut of pearl millet is quite confused in the literature. Several apparently unique species have been reported or implicated in the cause of smut diseases of pearl millet. For example, Rachie and Majmudar wrote (1980):

The fungus Tolyposporium senegalense Speng. [sic], T. bullatum Schroet., and Sorosporium bullatum Schroet. was first reported from Africa (Corbetta 1954); but Mundkur (1940) reported its occurrence in the region of Poona, India. Hirschorn (1941) suggested the name T. bullatum, as T. senegalense was only a synonym of the same species. It also attacks Echinochloa crusgalli in Germany.

Corbetta's (1954) paper is in Italian, and from what I can understand, he is attempting to clarify the nomenclature of the smut pathogen of Panicum crus-galli and P. erectum. I believe that his final conclusion is that Tolyposporium bullatum, Sphacelotheca destruens, and Sorosporium panici-miliacei should be named Sorosporium bullatum. Pearl millet, or an associated smut pathogen of pearl millet, is not mentioned.

The argument for synonymy of Tolyposporium senegalense and T. bullatum was made by Hirschorn (1941). The paper is written in Portuguese (?) and I believe that Hirschorn promoted lumping these two species based on morphologic similarities. Cross-inoculation studies were unsuccessful, but he attributed this to physiological differences. Although similar morphology may be adequate to include the fungi in the same genus, sporidial cross-compatibility should probably be examined before concluding that the fungi are identical, particularly since the two fungi are reproductively isolated from each other because of host specificity.

Vanky (1977) split several species out from Tolyposporium into a new genus, Moesziomyces. After examining the type specimens, it was concluded that T. penicillariae and T. senegalense were the same species, M. penicillariae, which differed from M. bullatus. Mordue (1995) reinforced the observation that M. penicillariae and M. bullatus are morphologically similar, but there appear to be biological differences in host specificity and possibly in germination.

Mundkur (1940) described a fungus named Ustilago penniseti. This specimen was described from infection on Pennisetum fasciculatum and has not been demonstrated to be pathogenic to pearl millet, Pennisetum glaucum. Subsequent observations of the disease have not been reported.

Likewise, Mundkur (1939) stated that he considers Tilletia pennisetina and Neovossia barclayana as synonyms. These type specimens were collected from Pennisetum alopecuroides and P. orientale, respectively, and thus cannot be considered to be pathogenic to pearl millet without completing Koch's postulates. No subsequent observations of the disease have been reported.

Mundkur's (1939) original report of Tilletia ajrekari as a pathogen of pearl millet should also be examined closely. In the description, he stated that a single infected ovary was found in greenhouse-grown plants. Examination of other plants in the greenhouse and field failed to identify any other similar sori. In this case, a new species was described based on spore characteristics of a single infected ovary. In a later publication (Mundkur and Thirumalachar 1952) the description is the same; however, here it is implied that several ovaries were infected. Because of the nonsystemic infection and other characteristics of the spores, he stated that it may be a species of Neovossia. "This can be definitely decided only after the germination of the spores has been obtained." In this reference he also states "germination unknown" regarding the spores. This leads me to believe that no inoculations were ever performed. This possibility, plus the discrepancy between a single infected sorus as described in the 1939 paper and several sori in the 1952 reference leads me to question whether this work is valid or can be reproduced.


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United States Department of Agriculture
Agricultural Research Service

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Original posting: June 5, 1999.

Last Modified: 2/6/2002
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