Root Disease Management Guidebook-Introduction

[Root Disease Management Guidebook Table of Contents]

Introduction

Dwarf mistletoes are parasitic seed plants affecting several coniferous tree species in forested ecosystems of North America, including British Columbia. Dwarf mistletoes are integral parts of these forested ecosystems and can have both beneficial and detrimental effects on the health, function and productivity of forests. Negative effects of dwarf mistletoes include reducing tree growth, lowering wood quality and causing mortality.

Forest harvesting, regeneration, and stand management activities can either limit or enhance the spread and intensification of dwarf mistletoes. As obligate parasites, dwarf mistletoes can be effectively controlled by removing live host trees. Spread and intensification are enhanced when dwarf mistletoe infection sources remain in and around openings or within thinned or partial cut harvested stands.

The major dwarf mistletoes covered in this guide book are:

Lodgepole pine dwarf mistletoe (Arceuthobium americanum); damage code DMP[1]
Western hemlock dwarf mistletoe (A. tsugense); damage code DMH
Western larch dwarf mistletoe (A. laricis); damage code DML
Douglas-fir dwarf mistletoe (A. douglasii); damage code DMF.

In British Columbia, dwarf mistletoes significantly affect forests and forest resource management objectives in the following areas and forest types:

coastal western hemlock forests
interior lodgepole pine forests
southern interior Douglas-fir and western larch forests.

Evaluation and suitable prescriptions for dwarf mistletoes are required in these situations.

The Forest Practices Code of British Columbia Act and regulations require detection and evaluation of dwarf mistletoes as part of forest management planning, prescriptions, and operations.

This guide deals with treatment and management of forest ecosystems to prevent or reduce detrimental effects of dwarf mistletoes.

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