Possible Root Transmission of the Red Ring Nematode (Rhadinaphelenchus cocophilus) to Coconut Palms. Dulce R. N. Warwick, National Center for Coconut Research Embrapa, CP 44, Aracaju, SE 49000, Brazil. A. P. T. Bezerra, National Center for Coconut Research Embrapa, CP 44, Aracaju, SE 49000, Brazil. Plant Dis. 76:809-811. Accepted for publication 12 December 1991. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1992. DOI: 10.1094/PD-76-0809.

The significance of root transmission of the red ring nematode (Rhadinaphelenchus cocophilus) to coconut palms (Cocos nucifera) was investigated in a screen-house experiment. Transmission by root contact occurred in seven of 15 plants growing around five inoculated plants. In another experiment, each plant became infected when a nematode suspension was placed on the mechanically damaged roots. Young seedlings planted in a hole where previously diseased palms were growing did not develop the typical symptoms of red ring disease. Red ring nematodes could not successfully colonize the husk tissue or the bole area. Seedlings were also artificially infected with red ring nematodes and observed for 30 wk. Nematodes could be extracted from the seed of only one plant. At the end of the 30-wk period, no nematodes could be detected. Thus, seedling tissue may not be suitable for development of red ring nematodes.