Hemlock Dwarf Mistletoe Stand Establishment Decision Aid

Abstract

Hemlock dwarf mistletoe (Arceuthobium tsugense), a parasitic seed plant, is endemic and common in coastal western hemlock forests from northern California to southern Alaska. The mistletoe spreads by seeds dispersed from residual to nearby trees. Over time, infestations can significantly reduce tree growth. Annual growth losses attributed to mistletoe infection are estimated at over 1 million m3 in coastal British Columbia. Variable retention silviculture regimes recently implemented in hemlock-dominated coastal forests create conditions that could exacerbate the spread, intensification, and effects of mistletoe.

The Stand Establishment Decision Aid (SEDA) format has been used to extend information on various vegetation and forest health concerns in British Columbia. This is the second SEDA produced for the Coast Forest Region. It summarizes information that relates current management regimes to the spread and effects of hemlock dwarf mistletoe. The first page provides general information, hazard ratings for the biogeoclimatic zones and subzones of the Coast Forest Region, and silvicultural considerations for hemlock dwarf mistletoe. The second page outlines the growth and yield implications and other effects and associations of the pathogen. This page also includes a valuable resource and reference list to provide readers with more detailed information. Reference material that is not available on-line can be ordered through libraries or the Queen�s Printer at: www.qp.gov.bc.ca.