Review of Studies on the Cadang-Cadang Disease of Coconut

Abstract

The cadang-cadang of coconut is a blight characterized by die-off of trees until the patch is laid bare The symptoms are as follows. Water-soaked spots are produced on leaflets, and the leaves become small as the disease grows severe; the crown of leaves is parted into two groups (a tuft of young leaves and a group of old, horizontal or drooping leaves), and the stipules are profuse and persistent. On the trunk, the leafscars are far apart in the mild stage but very close together in the severe stage. The fruits are big and profuse in the mild stage; in the severe stage of the disease, the fruits are few, small, misshapen, and scarified. To explore the likelihood that the disease is pathogenic, field surveys were undertaken designed to follow its spread. The researchers hypothesized that the disease originated in San Miguel Island, Tabaco, Albay, and fanned out to outlying areas including the provinces of Sorsogon, Camarines Sur, Camarines None, and Catanduanes. This pattern of spread may be mooted. Complementarity, there were extensive attempts to transmit the disease mechanically and biologically using insect vectors. The rare claims of having successfully transmitted the virus (gauged by the production of water-soaked spots on leaflets) have not been verified. More recently, extensive studies were conducted to prove the viroid nature of the disease. The viroid (ccRNA) was characterized biochemically as regards reaction to solvents, behavior in electrophoretic separation, and size of molecule and its structure. On the other hand, the search for a soil constituent as causative factor of the disease became focused on the rare earth especially lanthanum. Given in low concentration, lanthanum was beneficial to short-lived plants or to young perennials; however, in the long run, perennials got killed late in life by dilute solution of lanthanum.

Source or Periodical Title

Botanical Review

ISSN

68101

Page

182-196

Document Type

Article

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