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Effect of Root-knot Nematode-Fungi Combinations on Cotton Seedling Disease. Jean Cauquil, Plant Pathologist, Institut de Recherches du Coton et des Textiles Exotiques, 34 rue des Resnaudes, Paris 17°, France; Raymond L. Shepherd, Research Agronomist, Crops Research Division, ARS, USDA, Alabama Agricultural Experiment Station, Auburn University, Auburn 36830. Phytopathology 60:448-451. Accepted for publication 2 October 1969. DOI: 10.1094/Phyto-60-448.

Synergistic effects on the severity of cotton (Gossypium hirsutum) seedling diseases were found between root-knot nematodes (Meloidogyne incognita acrita) and Alternaria tenuis, Fusarium oxysporum f. sp. vasinfectum, Glomerella gossypii, and Rhizoctonia solani. Cotton seedling disease was severe in the presence of high inoculum levels of G. gossypii and R. solani without nematodes. At these inoculum levels, nematode effects were masked. A. tenuis and F. oxysporum f. sp. vasinfectum alone caused slight or no disease, but when combined with nematodes, disease was severe. Chaetomium spp., Cladosporium spp., Fusarium moniliforme, and Xanthomonas malvacearum caused little or no seedling damage, either alone or combined with nematodes.