The lack of persistence of Ophiostomataceae fungi in Pinus radiata 3 years after damage by the bark beetle Hylastes ater, and the subsequent colonisation by Sphareopsis sapinea

Abstract

A survey established in 2002 of 1-year-old Pinus radiata seedlings in New Zealand confirmed the presence of a number of members of the Ophiostomataceae family within the seedlings following damage. The persistence of fungi in P. radiata trees for extended periods following prior damage to the seedlings by the bark beetle Hylastes ater was studied subsequently as is reported herein. A random selection of the remaining P. radiata trees from the original sites were destructively sampled in 2005, approximately 3 years after the initial study. The diameter of each tree was measured, visual observations of any damage to tree were noted and any potential sapstaining fungal species were isolated. Sphareopsis sapinea was isolated from 6 to 16% of trees, despite not being isolated from any trees in the first study. With the exception of Ophiostoma setosum isolated from a single tree, no members of the Ophiostomataceae family were isolated this second time from the trees. The present study highlights that Ophiostoma species initially inhabited P. radiata seedlings following bark beetle attack, but their presence was not sustained over the three year period, showing that they were not endophytes in P. radiata. The asymptomatic persistence of S. sapinea in seedlings and larger P. radiata trees, however, is of significant concern for the forest industry.