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Distribution and Grasshopper Transmission of Northern Jointvetch Anthracnose in Rice. X. B. YANG, Department of Plant Pathology, University of Arkansas, Fayetteville 72701. D. O. TeBEEST, Department of Plant Pathology, University of Arkansas, Fayetteville 72701, and R. J. SMITH, JR., USDA-ARS, University of Arkansas Rice Research and Extension Center, Stuttgart 72160. Plant Dis. 78:130-133. Accepted for publication 6 October 1993. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0130.

Surveys during 1990-1992 showed that northern jointvetch (Aeschynomene virginica) plants were distributed in patches of various sizes in rice fields. Plant density in individual patches varied from 0.5 to 8.4/m2. Incidence and severity of anthracnose caused by Colletotrichum gloeosporioides f. sp. aeschynomene varied from 0 to 100% among individual patches, indicating that disease development within individual patches was independent of disease development in other patches. High mortality of northern jointvetch plants was observed in some patches. Grasshoppers frequently were observed feeding around or on anthracnose lesions of northern jointvetch. In eight separate experiments, about 20% of the grasshoppers collected from fields with diseased northern jointvetch were infested with the pathogen and transferred the pathogen to healthy plants after feeding. After pathogen-free grasshoppers fed on anthracnose lesions, 65-75% transmitted the pathogen to healthy plants. Grasshoppers (Conocephalus fasciatus and Melanoplus differentialis) may be important vectors in the dispersal of inoculum in northern jointvetch in rice.

Keyword(s): biological control