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Oregon State University
College of Agricultral Sciences
OSU Extension Service
OSU Extension Catalog
Identifying and Managing Christmas Tree Diseases, Pests, and Other Problems
Diseases
Annosus Root Rot
Phytopthora Root Rot
Grovesiella Canker
Interior Needle Blight
Rhabdocline Needle Cast
Swiss Needle Cast
Melampsora Needle Rust
Pucciniastrum Needle Rust
Uredinopsis Needle Rust
Insects
Twig Aphid
Conifer Root Aphid
Conifer Aphids
Balsam Wooly Adelgid
Cooley Spruce Gall Adelgid
Douglas-fir Needle Midge
Spruce Spider Mite
Eriophyid Mites
Root Weevil
Douglas-fir Twig Weevil
Disorders
Interior Needle Loss
Yellow-green Mottle Syndrome
Current Season Needle Necrosis (CSNN)
Damage
Weather Damage
Frost Damage
Winter Injury
Drought
Heat Damage
Chemical Damage
2, 4-D and Triclopyr
Fertilizer Burn
Glyphosate (Roundup)
Triazines
Vertebrate Damage
Deer, Elk, Mice & Voles
Rabbits & Birds
Mechanical Damage
Mechanical Damage
About
Authors & Acknowledgments
Copyright and Disclaimer
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Current Season Needle Necrosis (CSNN)
Photo by Ralph Byther, Washington State University.
Causes
Photo by Chal Landgren, OSU.
Unknown
Signs & Symptoms
Photo by Chal Landgren, OSU.
Tan, discolored bands on random needles at the tip of or on the entire needle
Affected portions turn reddish-brown, and may be shed if the entire needle is affected.
Symptoms present on newly developed needles, often following high temperature events.
Secondary organisms can colonize the necrotic tissue.
Where to Look
Valley sites and areas prone to high temperatures during shoot elongation
Similar Symptoms As
Needle rust
Environmental stress
Management Options
Plant resistant species or sources.
Shade trees during shoot elongation. Shading may reduce symptoms.
Do not rely on spray treatments, which have shown limited benefit.
Remove highly susceptible trees.
Scouting
On noble fir, look for symptoms in upper part of the tree. Damage in other species can vary.
Check for development of symptoms after high temperature events (over 85°F).
Examine symptomatic needles during late summer and fall. Symptoms are present on all sides of the trees.
Host Susceptibility
View text version
High susceptibility: Grand fir, Noble fir
Low susceptibility: Nordmann fir, Turkish fir
Management Calendar
View text version
Look for necrotic needles: All year round
Check for symptoms, which commonly develop after high temperatures: Mid-June through August
Plant resistant species: February through April
Disorders
Interior Needle Loss
Yellow-green Mottle Syndrome
Current Season Needle Necrosis (CSNN)
OSU Extension Publications
OSU Extension Catalog
Best Management Practices for Christmas Tree Export
Buenas Prácticas de Manejo para la Exportación de Árboles de Navidad
Identifying and Managing Christmas Tree Diseases, Pests, and Other Problems
Identificación y Manejo de Enfermedades, Plagas y Otros Problemas en Árboles de Navidad
Identifying and Managing Christmas Tree Diseases, Pests, and Other Problems
Diseases
Annosus Root Rot
Phytopthora Root Rot
Grovesiella Canker
Interior Needle Blight
Rhabdocline Needle Cast
Swiss Needle Cast
Melampsora Needle Rust
Pucciniastrum Needle Rust
Uredinopsis Needle Rust
Insects
Twig Aphid
Conifer Root Aphid
Conifer Aphids
Balsam Wooly Adelgid
Cooley Spruce Gall Adelgid
Douglas-fir Needle Midge
Spruce Spider Mite
Eriophyid Mites
Root Weevil
Douglas-fir Twig Weevil
Disorders
Interior Needle Loss
Yellow-green Mottle Syndrome
Current Season Needle Necrosis (CSNN)
Damage
Weather Damage
Frost Damage
Winter Injury
Drought
Heat Damage
Chemical Damage
2, 4-D and Triclopyr
Fertilizer Burn
Glyphosate (Roundup)
Triazines
Vertebrate Damage
Deer, Elk, Mice & Voles
Rabbits & Birds
Mechanical Damage
Mechanical Damage
About
Authors & Acknowledgments
Copyright and Disclaimer
Order
Order Publication