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ARS Home » Plains Area » Mandan, North Dakota » Northern Great Plains Research Laboratory » Research » Publications at this Location » Publication #193236
Title: PLATYSPORA LEAF SPOT

Author
item Krupinsky, Joseph
item Cline, Erica

Submitted to: American Phytopathological Society Press
Publication Type: Book / Chapter
Publication Acceptance Date: 6/20/2006
Publication Date: 1/31/2010
Citation: Krupinsky, J.M., Cline, E. 2010. Platyspora leaf spot. p. 42-43. 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: Platyspora leaf spot is a plant disease on wheat. The disease has been previously reported on the stems and leaves of numerous plants at high altitudes. Wheat and rye (but not barley, oats, triticale, or wheatgrass) are now known to be infected in the Great Plains of North America. At present, wheat infections are infrequent and not economically important. They appear as isolated, irregular, yellow-brown spots. In the greenhouse, symptoms appear four to six days after inoculation, and infection requires 24-72 hr of continuous wetness. Natural infections eventually produce diagnostic fungal structures on wheat straw. Ascospores are airborne. Controls are largely unnecessary; however, those described for leaf spots on wheat should also control Platyspora leaf spot.

Technical Abstract: Platyspora leaf spot, caused by Comoclathris pentamera (P. Karst.) S. Ahmad (= Graphyllium pentamerum (P. Karst.) M.E. Barr; = Platyspora pentamera (P. Karst.) Wehm.) was first reported as a plant disease on wheat in 1971. The fungus previously was known only at high altitudes, where it persists on the stems and leaves of numerous monocotyledonous and dicotyledonous hosts. Wheat and rye (but not barley, oats, triticale, or wheatgrass) are now known to be infected in the Great Plains of North America. At present, wheat infections are infrequent and not economically important. They appear as isolated, irregular, yellow-brown spots without internal fructifications. In the greenhouse, symptoms appear four to six days after inoculation, and infection requires 24-72 hr of continuous wetness. Natural infections eventually produce diagnostic pseudothecia on wheat straw. Ascospores (eight per ascus) are airborne, distinctly flattened, 20-30 x 10-13 x 7-9 'm, and eight-celled at maturity. Each has four transverse septa, and longitudinal septa divide the three median cells. Controls are largely unnecessary; however, those described for Stagonospora and Septoria leaf spots should also control Platyspora leaf spot.