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From the MDA: Check Christmas trees and holiday greenery for pests!

Source: Plant Pest Insider by the Minnesota Department of Agriculture, December 2019

Your holiday greenery may smell and look beautiful, but keep an eye out for insects and diseases that can be transported on these plants when shipped into Minnesota from other parts of the country. Some of these can become invasive and harmful to our Minnesota trees, forests and landscapes. 

While the Minnesota Department of Agriculture (MDA) inspects greens and other decorative plant materials, we can all do our part to keep Minnesota landscapes and forests healthy.
  • Do not toss Christmas trees or holiday greenery into your backyard woods or compost pile. 
  • Instead, use a city or county organized tree and greenery pick up service to dispose of these plant materials safely.
  • You can also burn greenery. Be sure to follow your local ordinances about burning.
  • Buy locally grown trees and greens to support our economy, our neighbors and avoid bringing pests into our state.
Report any findings to the MDA: (888) 545-6684 or arrest.the.pest@state.mn.us

Four pests to be on the look out for this holiday season

Elongate hemlock scale
Found almost exclusively on the underside of conifer needles. Very small and inconspicuous, this insect can look like dirt or debris.


Elongated hemlock scale (Photo: MDA)


Oriental bittersweet
This non-native vine has been used in decorative wreaths, arrangements, and crafts for many years. The reddish-orange fruits have yellow capsules that open to create a flower-like look and easily spread seed by wind and birds when placed outside. According to the MDA, oriental bittersweet is designated as a noxious weed on Minnesota's Eradicate List.


Oriental bittersweet (Photo: MDA)

Boxwood blight
Boxwood is a desirable broadleaf evergreen grown as a landscape plant here in Minnesota. Boxwood shoots are often used in holiday wreaths, garlands, and arrangements. According to the MDA, many states received shipments of holiday decorations infected with boxwood blight in 2018. This disease is caused by an invasive fungus (Calonectria pseudonaviculata) that causes established boxwood shrubs to develop leaf spots, stem lesions, and leaf drop, and can kill young boxwood plants. It can also affect sweet box (Sarcococca spp.), and the ground cover Japanese spurge (Pachysandra) Boxwood blight has been found in 28 states, but hasn't been identified  in Minnesota. 

The MDA is asking everyone to examine all boxwood shoots in your holiday decorations for leaf spots and stem lesions. Leaf spots are tan in the center with a dark purplish black margin, and infected stems have long thin black streaks.


Leaf spots caused by boxwood blight
(Photo: MDA)

Gypsy moth
Check your Christmas tree for gypsy moth egg masses on the trunks and branches. These egg masses are tan and fuzzy and about the size of a quarter. Each egg mass can contain 500 to 1,000 eggs.


Gypst moth egg mass on evergreen branch
(Photo: MDA)



Posted by: Julie Weisenhorn, Extension Educator - Horticulture

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Comments

Unknown said…
Excellent reminders to watch for those nasty pests, even at this busy time of the year!! I wouldn't have paid any attention to or even looked for insects and diseases on holiday greenery, but I will now! Thanks for sharing this great reminder! Happy Holidays!