Galls of Cacoa in Papua and New Guinea.

Abstract

Fan and knob galls of cacao, previously recorded in Central America, are now recorded in Papua and New Guinea. Neither of these galls, the causes of which have not been determined, are of economic importance in the Territory at present. Studies carried out on knob gall include microscopic examination of the tissues, isolation in nutrient agar of fungi present in the galls, inoculations with gall tissue (which did not result in galls), excision of galls in the field and the production of new galls from some old excision scars. The presence of knob galls could not be correlated with any nutritive state of the frees. No significant difference was found in auxin activity or in gibberellin levels in galled and normal samples and no virus-like particles were found in negatively stained-cell extracts in the electron microscope.