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Sclerotinia Root Rot: A New Threat to Buckwheat Seedlings in India

In the temperate regions of India, buckwheat (Fagopyrum esculentum Moench and F. tataricum Gaertn.) is produced extensively. During the first week of June in 2001 and 2002, a severe incidence of root rot (35% seedling mortality) was observed in the Sangla Valley of Himachal Pradesh when the crop was at the seedling stage. The disease was more severe on F. tataricum, resulting in a poor crop stand. The disease appeared as water-soaked areas on the upper portion of the root, which turned brown. The brown patches gradually proceeded downward covering the whole root system. The above ground foliage wilted and died. The disease spread rapidly with cloudy, humid weather and day temperatures ranging from 15 to 20°C. Mycelium of the causal fungus was inter- and intracellular type with hyaline, branched, and septate hyphae. Sclerotia were pink but later turned black, measuring 3.0 to 3.5 mm in diameter. The pathogenicity of the causal fungus was proved following Koch's postulates. The pathogen was identified as Sclerotinia sclerotiorum (Lib.) de Bary (2). In Japan, the association of S. libertiana on buckwheat has been reported (1). To our knowledge, this is the first report of Sclerotinia root rot on buckwheat from India.

References: (1) H. Singh and T. A. Thomas. Indian Counc. Agric. Res. New Delhi, India, 1978. (2) H. J. Willets and J. A. L. Wong, Bot. Rev. 46:101,1980.