Rhadinaphelenchus cocophilus (Cobb, 1919) Goodey, 1960 as a Root Parasite of Coconuts

Abstract

While investigating Red Ring Disease of coconuts, the authors detected Rhadinaphelenchus cocophilus (Cobb, 1919) Goodey, 1960 in the root systems of three otherwise healthy coconut trees. One of these was about seven years old; the roots and the stem were sampled five times weekly but no stem or petiole infection was detected. A similar state of affairs was detected in the second tree. In neither case over a period of several weeks was there evidence of upward movement of the worm into the stem. The third tree was more interesting: the first sampling disclosed the presence of the nematodes in only one sample of roots out of four taken equidistantly around the stem; subsequent examination showed that the infection spread through the root system in the neighbourhood of the base of the tree until at the end of one month, worms were recovered from all parts of the proximal root system and the population had increased to 100–150 worms per gm. of root: many of these were sexually mature; after a further two weeks, there was still no upward movement into the stem.