A disease survey carried out in 1998, 1999, and 2000 in the states of Aguascalientes, San Luis Potosí, and Zacatecas revealed the dispersal of Meloidogyne spp in this region of Mexico. Pepper (Capsicum annuum L.) Mirasol type plants showing general chlorosis, root rot, and galls were observed in central Zacatecas and western San Luis Potosí. Dry bean (Phaseolus vulgaris L.) plants (Landrace Flor de Mayo) collected in western San Luis Potosí and Aguascalientes also showed root galls. Roots of squash (Cucurbita spp) and sunflower (Helianthus annuus L.) plants that showed galled roots were found under dryland conditions in northern Zacatecas. Nursery peach (Prunus persica L.) plantlets with no foliar symptoms but showing severe root galling were detected in Zacatecas. Perineal patterns of Meloidogyne females obtained from those galled roots were coincident with those of M. incognita according to pictoral keys (1). This is the first report of M. incognita affecting these hosts in that region of the country. Alfalfa (Medicago sativa) plants collected in Aguascalientes showed galls caused by Meloidogyne spp; this is the first report of this nematode affecting alfalfa in the state. Volunteer onion (Allium cepa L., ‘Grano Blanco’) plants growing in a squash field in eastern Zacatecas had galled roots; a few Meloidogyne spp. females were obtained from small galls. This is the first report of the root-knot nematode affecting onion plants in north central México. Onion is known to be a host for several species of this nematode (2). Stunted, chlorotic squash plants had roots severely galled by Meloidogyne spp, but pepper crops growing in the same field in previous years showed general chlorosis, reduced size, and poor yield did not have root galls.
References: (1) Eisenback, J. D., et al. 1983. Guia para la identificación de las cuatro especiales más comunes del nematodo agallador (Meloidogyne spp.) con una clave pictorica. International Meloidogyne Project, Raleigh, NC. (2) Schwartz, H. F., and Mohan, S. K. 1995. Compendium of onion and garlic diseases. American Phytopathological Society. St. Paul. MN.