Mortalities of young established radiata pine associated with Phytophthora spp. in the Donnybrook Sunkland plantations in Western Australia

Abstract

Summary Scattered sudden deaths of young Pinus radiata have been observed in the Donnybrook Sunkland plantations in Western Australia. Transplanting losses were generally high, and mortalities gradually declined in the early years after planting, with deaths ceasing in unthinned stands by age 7 to 8 years. Deaths after establishment were more frequent in areas previously affected by jarrah dieback (Phytophthora cinnamomi). There was a resurgence of deaths following pruning and light culling operations in a 6-year-old stand. Root and soil samples were collected from around dead, dying and healthy Pinus radiata aged between 1 and 7 years. Phytophthora spp. (predominantly P. cinnamomi) were isolated directly from the roots of 64% of dying and recently-killed trees and 6% of adjacent apparently-healthy trees. The other species identified were P. cryptogea, P. megasperma var. sojae and P. citricola. Recoveries of Phytophthora spp. from soil were less frequent than from the roots of affected trees. There appear...