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Root-Knot Nematode Damage to Dioscorea rotundata. U. G. Atu, Plant Nematologist, National Root Crops Research Institute, Umudike-Umuahia, University of Nigeria, Nsukka. S. O. Odurukwe, Biometrician, National Root Crops Research Institute, Umudike-Umuahia, and R. O. Ogbuji, Associate Professor, University of Nigeria, Nsukka. Plant Dis. 67:814-815. Accepted for publication 3 January 1983. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-814.

In pot experiments conducted in the glasshouse, white guinea yam cv. Igwe was inoculated with Meloidogyne incognita at inoculum levels ranging from 50 to 156,250 eggs per plant. At a soil temperature of 28 C, the economic threshold and economic injury level were fixed at 250 and 1,250 nematodes per plant, respectively. Tubers from pots inoculated with more than 1,250 nematodes per plant were so heavily galled that the market value was reduced by 40%.