DECAY FEATURES OF THE XYLEM CELLS OF A SHOREA GIBBOSA STEM CANKER

Abstract

Xylem decay of a serious stem canker of Shoreagibbosa found in Bukit Soeharto Educational Forest of Mulawarman University, East Kalimantan has been investigated. Fungi infection into the standing tree is suspected as a causal main factor of the disease and xylem decay. Colonization of fungal hyphae and cell wall degradation were clearly observed under scanning electron microscopy (SEM). Xylem fibers, rays and parenchyma cells of were degraded, however most of vessel elements remain intact. Penetration of the fungal hyphae into the xylem cells induced the numerous holes on fiber and axial parenchyma cell walls, and pits of vessel elements become distorted and enlarged. The loss of few axial parenchyma cell walls and the fiber wall thinning were also detected.