VIEW ARTICLE

Physiology and Biochemistry

Collection and Properties of Phloem Sap from Healthy and Lethal Yellowing-Diseased Coconut Palms in Jamaica. S. J. Eden-Green, Formerly Coconut Industry Board, P.O. Box 204, Kingston 10, Jamaica, Present address: Plant Pathology Department, Rothamsted Experimental Station, Harpenden, Herts. AL5 2JQ, England; H. Waters, Formerly Coconut Industry Board, P.O. Box 204, Kingston 10, Jamaica, Present address: Botany Department, University of the West Indies, Mona, Kingston 7, Jamaica. Phytopathology 72:667-672. Accepted for publication 3 September 1981. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-667.

Techniques were devised for collecting phloem sap (coconut toddy) from inflorescences and cut trunks of coconut palms under field and laboratory conditions. Although inflorescence sap was obtained from cultivars showing both high and low susceptibility to lethal yellowing (LY) disease, it could not be obtained from the widely grown susceptible cultivar Jamaica Tall. Inflorescence sap had dry weights of 120–190 mg/ml and osmotic pressures (OPs) of 500–900 mosmol/kg; samples of trunk sap from healthy palms were more dilute (60–90 mg/ml), but had proportionately higher Ops (400–550 mosmol/kg). Volumes of trunk sap obtained from LY-diseased palms decreased as symptoms became more advanced, and the samples were more concentrated. Sap was not obtained from palms beyond the mid to late yellowing stages of the disease. No conclusive evidence was obtained for the presence or growth of mycoplasmalike organisms in sap from diseased palms, but samples from inflorescences and trunks of both susceptible and resistant cultivars were suitable as basal media for the growth of representative species of three genera of mycoplasmas.