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Host-Parasite Relationships in Root-Knot Disease of White Mulberry

March 2001 , Volume 85 , Number  3
Pages  277 - 281

P. Castillo , Research Nematologist, Instituto de Agricultura Sostenible, Consejo Superior de Investigaciones Cientificas (IAS-CSIC), Apdo. 4084, 14080-Córdoba, Spain ; M. Di Vito and N. Vovlas , Nematologist Research Leader, Istituto di Nematologia Agraria, Consiglio Nazionale delle Ricerche, Via G. Amendola 165/a, 70126-Bari, Italy ; and R. M. Jiménez-Díaz , Professor, IAS-CSIC and Escuela Técnica Superior de Ingenieros Agrónomos y Montes (ETSIAM), Universidad de Córdoba, Apdo. 3048, 14080 Córdoba

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Accepted for publication 12 November 2000.

Severe infections of white mulberry feeder roots and heavy soil infestations by Meloidogyne arenaria race 2 were found in southern Spain. This is the first record of M. arenaria on white mulberry in Europe. Morphometric observations, analysis of the esterase electrophoretic pattern, and artificial inoculations of race differentials were used to characterize nematodes. Nematode-induced mature galls were spherical and usually contained one or more females, males, and egg masses with eggs. Feeding sites were characterized by the development of giant cells that contained granular cytoplasm and many hypertrophied nuclei. Giant cell cytoplasm was aggregated along a thickened cell wall. Vascular tissues within galls appeared disorganized. The relationship between the initial nematode population density (Pi) in a series from 0 to 1,024 eggs and juveniles/cm3 soil and growth of white mulberry seedlings was tested in the greenhouse. A Seinhorst model was fitted to plant height and top fresh weight. Tolerance limits of white mulberry to M. arenaria race 2 for plant height and top fresh weight were, respectively, 1.1 and 1.38 eggs and juveniles/cm3 soil. The minimum relative values for plant height and top fresh weight were 0 at Pi ≥ 64 and Pi ≥ 128 eggs and juveniles/cm3 soil, respectively. Maximum nematode reproduction rate was 435-fold at the lowest Pi.

Additional keywords: histopathology, Morus alba, pathogenicity, threshold limit

© 2001 The American Phytopathological Society