Factores intrínsecos que influyen en la eficacia de la prueba de laboratorio usada para evaluar la resistencia a Ceratocystis fimbriata en cacao

Abstract

The study was designed to determine the influence of several factors causing variation in the results obtained with a laboratory test developed by Delgado and Echandi to evaluate resistance of cocoa cultivars to Ceratocystis fimbriata. It was oriented to study the influence of inoculations made: 1) at different intervals of time after the branches were cut; 2) on sections from : a) branches of different thickness, b) branches, from different parts of the tree, and c) branches of different flushings; 3) on sections containing different tissues; 4) with inoculum prepared: a) from colonies produced on different substrates, b) with different spore concentrations, c) colonies of different age, and d) colonies obtained by several transfers from one isolated; and 5) seedling with different amounts of inoculum per square centimeter of branch section. A reduced growth of C. fimbriata was found on sections of suckers, even in those susceptible clones. Reduced variations were registered on sections of fan branches, and for this reason, they should be used on the laboratory tests. Also the age of the colonies had considerable influence on the fungus growth, probably due to reduction of spore viability after 30 days