Barrier Zone Formation: A Mechanism of Tree Defense Against Vascular Pathogens

Abstract

Barrier zones of axial parenchyma, were common in sapwood of trees which had recovered from vascular infections. They were a consistent feature in a representative sample of vascular wilt diseases when trees expressed some resistance. Vascular wilt diseases caused by Ceratocystis ulmi, C. coerulescens, Vertici/lium albo-{ltrum, and Fusarium oxysporum were studied.