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Insecticide toxicity, application efficacy, and degree-day modelling of an emergent Christmas tree pest, the Douglas-fir twig weevil (Cylindrocopturus furnissi)

The Douglas-fir twig weevil (Cylindrocopturus furnissi) is a problem on virtually all species of Christmas trees grown in the Pacific Northwest. Historically it has been a sporadic problem on Douglas-fir Christmas trees, particularly on trees planted on sites that are prone to moisture stress.

However, during the past few years, this pest has emerged as a significant export issue and affects growers’ ability to develop a quality tree for both domestic and export markets. It is also affecting the marketability of noble fir boughs in low elevation production stands. Twig weevil is the number one insect pest causing load rejections into Mexico. From 2014 to 2018 over 50% of the rejected Christmas tree loads shipped from Oregon to Mexico were rejected due to twig weevil. In an effort to develop a pest management strategy on adult weevils, the most susceptible life stage to contact insecticides, we:

  • Conducted laboratory experiments to determine which commonly used pesticides are most effective in killing twig weevils
  • Compared the effectiveness of aerial vs grand-based application of esfenvalerate (Asana XL) in killing twig weevils, and
  • Developed a degree-day model for adult emergence
  • Project ID18-07-WSU
  • CategoriesInsect Management
  • Growing Region(s)Pacific Northwest
  • Tree SpeciesFir
  • Investigator(s)Chastagner
  • Institution(s)The Davey Institute, Washington State University
  • Research Year2018
  • Publication Year2022
  • ReportDownload 📁