Current insects and diseases of concern in

Christmas trees

By Karl PulsOregon Department

ofAgriculture

Useful tools

• Pruners• Knife• Hand lens• Camera• Beating cloth• Clip board• Shovel• Chain saw

Pests ofTrue firs

Many pests feed on the underside of needles and branches or the interior of the tree

How to find Cinara occidentalis(Bark aphid)

• Lowest branches of noble and grand fir are more commonly effected.

• Prior season’s growth effected, not current season.

• Aphids feed at base of needle, not usually on the needle. Molt on needles.

• Leave a white to grey, waxy coating on the the branches and base of needles.

• Treat when nymphs are actively feeding.

C. occidentalis attacks older

woody growth, not current season

growth or needles. It feeds at the base

of needles

Cinara aphids on Noble fir

Cinara occidentalis

Cinara aphids atbase of needles

Noble fir

ces.ncsu.edu

Cinara sp.

Cinara sp.

C. occidentalis on Fraser fir

Syrphid fly larva feeding on aphids

C. occidentalis damagewith sooty mold

Noble fir

Balsam twig aphidon true fir

• BTA feeds on current season growth and twists needle growth, typically in late spring and early summer. Blue-green to gray aphid.

• Black sooty mold, which grows on the honeydew produced by BTA, becomes noticeable in Fall into the following spring.

• Yellow jackets are abundant around the new growth.

• Treat in late spring through mid-summer.• Effected branches can be pruned back in the fall.

Balsam Twig AphidDamage

Mindarus abietinus on Grand fir

Balsam Twig Aphidon grand fir

Mindarus abietinus

Root AphidsProsiphilus americanus

• Chlorotic trees can sometimes be a sign of root aphids. Digging the tree up is sometimes necessary to determine whether you have root aphids or not.

How to find root aphids

• Locate stunted, yellowing noble firs, especially young firs.

• Look for ants that forage around the base of the noble firs and travel underground. (Lasius sp.) These are honey-colored ants that move the root aphids from root to root and feed on the honeydew that the aphids excrete.

• Winged adult aphids migrate from Ash trees in spring. Nymphs can live year round on roots.

• Treatments?

Root aphids on Noble fir

Prosiphilus americanus

eol.org

Adelges piceae

Balsam woolly adelgid

Balsam woollyadelgid

• Balsam woolly adelgid is an aphid-like insect that effects balsam, fraser, noble firs, etc.

• Feeds on branches and trunk. • Causes swollen nodes.• Cottony appearance, can be quite numerous

Balsam woolly adelgidsfeeding on trunk

Adelges piceae

Balsam Woolly Adelgiddamage in Balsam fir

Adelges piceae

Treat BWA in June when

crawlers are active

Adelges piceae

Cooley spruce gall adelgid

• Cooley spruce gall adelgid is an aphid-like insect with a complex 2 year life cycle.

• It effects both douglas fir and spruce.• Damage is worse on spruce trees, forming

galls on branch terminals.• On douglas fir, needles are discolored where

adelgids feed.

Cooley spruce gall adelgid crawlers in Spring

Adelges cooleyi

Cooley Spruce Gall Adelgid adults form protective coating

Adelges cooleyi

Douglas FirNeedle Midge

Contarinia sp.

• Needle midge overwinters as a pupa in the soil under the tree where it has fed.

• It emerges as an adult in Spring, as early as the beginning of March.

• Control at that time is critical

Forestry Images.

Douglas firNeedle midge

larva

Goheen & Wilhite 2006.

Contarinia spp.

Douglas Fir Twig Weevil (DFTW)

• One species: Cylindrocopturus furnissii

• Mostly attacks Douglas fir, rare on Noble (stress symptoms)

• Quarantined on Douglas fir Christmas trees shipped to Mexico

Forestry images. Furniss 1942.Adult

Larva

1 mm

Douglas firTwig Weevil

• Cylindrocopturus furnissi is a small dark brown weevil with mottled white markings.

• Adults can be knocked off branches in summer and viewed on a drop cloth or beating cloth.

• Nymph damage occurs in early summer as dying and/or swollen branches. Use a knife to reveal the cambium layer where they are feeding.

• No treatment; prune out effected branches before adults emerge (before Summer).

Forestry images.

Oregon Dept. Agriculture.

Oregon Dept. Agriculture.

Oregon Dept. Agriculture.

Galleries caused by DFTW inDouglas fir branches

Forestry images.

Furniss 1942.

DFTW Damage

Diseases of Douglas fir and True fir

Sunburn on noble fir

Phytophthora Root Rot

Phytophthora root rot

Phytophthora root rot

Diagnosing Phytophthora root rot

Phytophthora root rotmanagement

• Reduce by improving drainage• Remove effected trees• Clean pruning equipment when dealing with

effected trees.• Plant resistant species

Annosus root rot

Chain saw diagnosisHeterobasidion annosum

Swiss Needle Cast

Swiss Needle Cast

Chal Landgren

Swiss needle caston Douglas fir

• Phaeocryptopus gaeumannii is a fungus that attacks needles in the spring and causes dieback the following season.

• Pseudothecia, black spores, can be seen in rows on the undersides of the needles.

• Needles drop by end of summer• Treatment period in late May through June

Swiss Needle Cast

Chal Landgren

Rhabdocline needle cast

Rhabdocline needle cast

Rhabdocline needle cast

Swiss and Rhabdocline needle cast

Uredinopsis rust on Grand Fir

Uredinopsis pustules on Grand Fir

Regulatory scouting

• For shipments to Hawaii:- No yellow jackets, slugs or snails allowed- Can be eliminated by mechanical shaking just prior to loading.• For shipments to Mexico:- Among other pests, no twig weevil, needle midge or yellow jackets are allowed (zero tolerance level).- Choose your fields carefully for shipments to Hawaii and Mexico

Christmas Tree Diseases, Insects & Disorders in the Pacific Northwest:

Identification and Management,

Editor- Gary Chastagner-Washington State

University ExtensionExcellent descriptions

and images of pests and other types of damage.

Christmas Tree Diseases, Pests and Other Disorders- Luisa Santamaria and Chal Landgren- Oregon State University Extension

Excellent field guide, images, descriptions and waterproof PagesOnline link: SERFcertified.orgLook under ‘farm resources’

Knowledge is power