VIEW ARTICLE

Etiology

Transmission of the RNA Species Associated With Cadang-Cadang of Coconut Palm, and the Insensitivity of the Disease to Antibiotics. J. W. Randles, Waite Agricultural Research Institute, University of Adelaide, South Australia 5064; G. Boccardo(2), M. L. Retuerma(3), and Erlinda P. Rillo(4). (2)Laboratorio di Fitovirologia Applicata, Via O. Vigliani, 10135 Turin, Italy; (3)(4)Bureau of Plant Industry, Guinobatan Experiment Station, Guinobatan, Albay 4908, The Philippines. Phytopathology 67:1211-1216. Accepted for publication 22 March 1977. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-1211.

Transmission to young coconut seedlings of the RNA species associated with cadang-cadang disease (ccRNA-1 and ccRNA-2) was achieved in two trials using either polyethylene glycol 6000- precipitated material, or nucleic acids extracted from this precipitate, as inoculum. Inoculation was by high pressure injection combined with either rubbing with Carborundum or slashing of petioles with a razor. The appearance of leafspotting symptoms on the young fronds of the RNA-positive inoculated palms between 19 and 22 mo after inoculation suggests that the agent may have been transmitted as a result of transferring the RNA by the inoculation procedure, and further suggests that the latent period lies between 1.5 and 2.0 yr. It has been confirmed that the cadang-cadang associated RNA species can be detected in the young fronds of palms before symptoms appear, consistent with the view that they are precursors of the disease. The failure of tetracycline and penicillin antibiotics to affect disease progress shows that prokaryotes probably have no primary role in the disease.