Testing Port-Orford-Cedar for Resistance to Phytophthora

Abstract

Root rot mortality of Port-Orford-cedar (Chamaecyparis lawsoniana) in western Oregon and Washington and northwestern California is caused almost exclusively by Phytophthora lateralis. Progression of P. lateralis lesions was slower on four cedar trees selected for phenotypic resistance than on randomly selected trees. Inoculations of seedlings and rooted cuttings with zoospores or infested soil and of excised branches with inserted mycelium gave similar results on the selected trees