Occurrence of red stanied in Aspidosperma quebracho-blanco wood

Abstract

Aspidosperma quebracho-blanco is one of the most important tree species of the Chaco Region. Its creamy white wood is commonly affected by a red stain, or false heart, produced by the fungus Fusarium scirpii. The objectives of this study were: (1) to determine the effect of the stain on the wood of the trees studied, (2) to establish whether a relationship exists between total radius and the affected radius, (3) to study the severity of the alteration through the obstruction of vessels in a cross section, and (4) to state the probable correlation between the obstruction and the color intensity of the stain on the wood. The samples came from cross sections of 36 trees taken at 1.30 m. In 10 samples, five radial specimens were taken at fixed distances, in the bark-pith direction, along the North radius. Based on the proportion of obstructed vessel area, a categorical range with three classes was defined. The results show that 71 % of the sections were affected, with no consistent relationship between the radius of the tree and the radius of the stained area. The color alteration is more intense at the center and diminishes towards the periphery. This is consistent with the decreasing trend in the percentage of hypha-obstructed vessels, which range from 53 % to 0 % toward the bark. The fungal hyphae penetrate through the vessel pits, causing partial or total obstruction. Even in the most severely affected sections, no structural anatomical changes were observed.