Infection, recovery from infection and resistance of apricot trees to Verticillium albo-atrum

Abstract

In infection studies of apricot with the microsclerotial form of Verticillium albo-atrum R. & B., otherwise described as V. dahliae Kleb., more apricot plants became infected and disease symptoms became more pronounced as concentration of inoculum increased. V. albo-atrum does not persist indefinitely in an infected tree but some factor causes the fungus to become ‘inactivated’, in which condition V. albo-atrum cannot be isolated from tissues previously known to have been infected. However, it is not known for certain whether inactivated fungus is dormant or dead. One selection ‘Zailisky Altai’, obtained from a wild population of Prunus armeniaca, was resistant to V. albo-atrum and is of potential value as a root-stock in soil infected with this fungus.