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Efficacy of eFume and Bluefume (HCN) fumigation in eradicating elongate hemlock scale on Christmas trees

EHS has a complex life cycle and can overwinter in several developmental stages. It feeds on the underside of needles, making it difficult for producers to follow the extent of infestations. Feeding can result in yellow mottling, though this symptom is often limited in properly maintained, Fraser fir Christmas tree plantations. What is more readily observed are the waxy filaments produced by developing male scales. These will appear on the tops of needles as branches blow in the wind, a sign readily apparent through the summer during shearing and other production practices.

Only crawlers can move onto new plant material or allow the pest to spread to new regions. EHS overwinters as multiple life stages including gravid females, and eggs can hatch over an extended period of timeonce plant material is harvested in late fall and moved to warmer locations. Although not know to occur in the western U.S., in 2019 EHS was detected on Fraser fir Christmas trees that were shipped from North Carolina to a number ofwestern states. Given the abundance of host material and the potential impact this pest would have on Christmas trees and forests in the PNW, regulatory agencies issued stop sale notifications and ordered infested trees to either be returned or destroyed.

  • Project ID21-08-WSU
  • CategoriesInsect Management
  • Growing Region(s)Mid-Atlantic
  • Tree SpeciesFir
  • Investigator(s)Chastagner
  • Institution(s)Washington State University, North Carolina State University, USDA ARS, San Joaquin Valley Agricultural Sciences Center
  • Research Year2021
  • Publication Year2022
  • ReportDownload 📁