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Introduction

Pests directly affect the quantity and quality of forest nursery seedlings and can indirectly cause losses by disrupting reforestation plans or reducing survival of outplanted stock. The movement of infested stock can disseminate pests to new areas. Since control of nursery pests may be based on pesticide usage, pest outbreaks may lead to environmental contamination.

In recent years, forest nursery managers have become increasingly aware of the significance of pest losses in British Columbia forest nurseries. This handbook was prepared to help in the identification and management of important diseases and insects in local nurseries.

In general, the length of each chapter is governed by the importance and amount of information available on a particular problem. If in-depth information on a problem was lacking, we omitted certain headings (e.g.,"Life History") in some chapters. Where warranted, we have included a general life history diagram for the pest.

We have attempted to provide sufficient information, to allow the user to recognize specific pests and to follow the logic of the management recommendations. Management practices that emphasize procedures other than the use of pesticides-e.g. prevention of pest problems and manipulation of cultural practices-are also given. These include:

For nursery site selection factors

Selecting a site with an adequate supply of water that is free of toxic chemicals, pH problems, and pests.

Selecting a site that is unaffected by adverse weather such as frost pockets and severe winds, and, in the case of bareroot nurseries, by additional factors such as flooding and heaving.

Avoiding sites with potential or known high levels of pests in the surrounding area (e.g. nearby forest stands with a high incidence of pine infested by western gall rust or nearby alfalfa fields which often harbour the Lygus bug).

For bareroot nurseries, selecting a sandy, well-drained, moderately acid soil. Such soils generally favor seed germination, seedling emergence, and growth, while hindering pest survival and proliferation. These soils are also easier to rid of pests.

For cultural practices

Preventing exposure of seedlings to factors such as frost damage, nutrient deficiencies, and toxic chemicals, which predispose them to pest invasion or injury, or both. Keeping seedlings healthy deters pest attack and losses.

Regulating environmental factors such as watering, aeration, and lighting, so that they hinder pest development or survival while not adversely affecting seedlings.

Using sanitation and pest exclusion practices such as:

  1. restricting or preventing movement of pest-infested stock or equipment among nurseries,
  2. removing or reducing weeds, and placing grass and ornamental plantings, well away from nursery area, (all of these can harbor insects and pathogens)
  3. removing infested seedlings or those that are potential sources for pest build up,
  4. periodically checking water supplies for pathogens,
  5. regularly checking soil amendments or container mix components for pests,
  6. ridding the area around the nursery of diseased trees and alternative hosts (e.g., for rusts), and
  7. where practical, producing stock in insect-proof greenhouses.

Establishing survey and monitoring programs (e.g., pheromone traps and yellow, sticky cards) for potential or incipient insect problems.

Bare fallowing soils or using crop rotation schemes unfavorable to pests.

Growing susceptible hosts outside pest-infected areas (e.g., where feasible, growing Abies species outside the balsam woolly adelgid quarantine area).

Planting resistant seedling species, provenances, or age classes in infested areas (e.g., putting transplants in areas prone to damping-off).

Using pesticides to prevent rather than to eradicate pest problems.