Red ring disease of coconuts in Trinidad and Tobago

Abstract

A short account is given of the origin of red ring disease of coconuts in Trinidad, its distribution elsewhere, and early investigations of the disease. Reference is made to serious losses caused in recent years. The symptoms of the disease are described and shown to be associated with the production of a strongly reducing substance in the periphery of the cortex of
young palms invaded by the nematode Aphelenchoides cocophilus.

Experiments on the inoculation of stems and roots are described. These showed penetration via the leaf axils to be the normal means of entry of the parasite, root infections, though successfully carried out artificially, being of no account under natural conditions. The coconut weevil, Rhynehophorus palmarum, and by inference Rhina barbirostris, also was shown to
be able to transmit the disease by burrowing in diseased debris in the cortex of affected palms, emerging with legs and body covered with this debris, and transferring it to wounds or to leaf axils in adjacent palms.

Reference is made to reports of natural and artificial alternative hosts of the parasite, and it is concluded that under natural conditions the disease is confined to the coconut palm, at least in the Lesser Antilles.

Control of the disease is shown to be possible by the removal of all infected palms and complete destruction of diseased tissues by fire.