Exotic, invasive pests are a constant concern for trading partners around the world. The Pacific Northwest (PNW), like other regions, is continually monitoring for new pest introductions. However, as international trade grows, pest introductions are on the rise. This guidebook provides PNW producers and shippers of Christmas trees with the tools to both identify and manage some of the export pests of greatest concern to trading partners.
Export pests listed on countries’ quarantine lists do not fall into neat categories. Some are simply “hitchhikers” that do not harm trees, whereas others can cause cosmetic or other types of tree damage. Some were originally introduced into the PNW from outside regions, and others are native species. Generally, the only trait these pests have in common is that they can cause containers or trailers to be rejected at a port of entry.
This guidebook outlines best practices to help minimize the presence of pests of concern. With many pests, the best time for control is months or years before harvest. With others, careful attention during harvest can reduce problems. Regulatory officials have the right to reject loads if they find any pest of concern and not just those on official quarantine lists.
Christmas tree pests are frequently site-related, and their populations fluctuate. For example, Douglas-fir needle midge may be a problem for a few years on some fields and then become insignificant. Slug populations can be low one year and high the next. Twig weevils can be an issue on some trees on dry sites and rarely seen in other locations. Due to this variability, growers should review this guidebook frequently.
This guidebook explains best practices for identifying and managing the most common pests causing rejection of Christmas trees shipped from Oregon: slugs, Douglas-fir needle midges, yellowjackets, root weevils, and Douglas-fir twig weevils. For each pest, the following topics are covered:
This guidebook also includes: