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United States Department of Agriculture

Agricultural Research Service

Title: Tar Spot

Author
item Krupinsky, Joseph

Submitted to: American Phytopathological Society Press
Publication Type: Book / Chapter
Publication Acceptance Date: June 20, 2006
Publication Date: January 31, 2010
Citation: Krupinsky, J.M. 2010. Tar spot. p. 84. IN: Compendium of Wheat Diseases and Pests, 3rd Edition. Edited by W.W. Bockus, R.L. Bowden, R.M. Hunger, W.L. Morrill, T.D. Murray, and R.W. Smiley. American Phytopathological Society Press, St. Paul.

Interpretive Summary: Tar spot, also known as black leaf spot, is a plant disease found on many grasses. Tar spot appears principally on perennial grasses in moist, shaded areas and is rare on wheat and other annuals. It is found primarily in temperate regions. The disease is readily recognized by its glossy black spots on leaf blades and sheaths. Fungal structures overseason on host plants and their residues. Grasses are the usual sources of primary inoculum for wheat infection. Images of symptoms on grass: http://www.bioimages.org.uk/html/r150287.htm . Tar spot on wheat is not economically important, and controls are not specified.

Technical Abstract: Tar spot of grasses, also known as black leaf spot, is found on most members of the Poaceae. Tar spot appears principally on perennial grasses in moist, shaded areas and is rare on wheat and other annuals. It is found primarily in temperate regions. The disease is readily recognized by its glossy black spots (c1ypei) on leaf blades and sheaths. The distinct, somewhat sunken c1ypei, 0.1-1 X 0.2-5 mm are crusty stromata of the causal fungus, Phyllachora graminis (Pers.:Fr.) Fuckel, with embedded perithecia. Ascospores are hyaline, ovoid to elliptical, unicellular, and 4-7 X 9-14 'm. Linochora graminis (Grove) Parbery is the anamorph. Stromata overseason on host plants and their residues. Grasses are the usual sources of primary inoculum for wheat infection. Images of asci and symptoms on grass: http://www.bioimages.org.uk/html/r150287.htm . Tar spot on wheat is not economically important, and controls are not specified.

Last Modified: 10/23/2014
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