ForesTree - A Guide to Tree Health

Pest and Disease Information

  • Pseudotsuga menziesii - Resistant to Oak Root Fungus. Susceptible to Beetle Borers, Western Spruce Budworm, Douglas Fir Beetle, Black Pineleaf Scale, Spruce Spider Mite and Douglas-fir Tussock Moth, Sudden Oak Death, Phytophthora, Root Rot, Oak Root Rot, Laminated Root Rot, Red Ring Rot, Mistletoe and Pitch Canker. Additional and expanded information listed below.

  • For further tree information:
       SelecTree (1199) | Silvics of North America
14 Records Found
Disease or Pest NameDescription of Disease or Pest

Dwarf Mistletoe
Arceuthobium douglasii

shootsSmall, yellow, leafless parasitic flowering plants. Reduces tree vigor (yellowing foliage) and can lead to mortality. Not found in Southern California.

Oak root fungus
Armillaria mellea

Armillaria_melleaArmillaria cases reduced terminal growth and general decline in affected plants, As the Armillaria advances dieback of twigs and branches (most apparent in hardwoods) can occur. Crown symptoms include chl...

Phytophthora Root and Crown Rot
Phytophthora cactorum

phytophthora_cactorumThis disease, as its name implies, is characterized by red-brown exudate oozing from bark fissures in cankers on lower parts of the mainstem of the tree. Wood behind the wet areas is dead and stained reddi...

Pitch Canker
Fusarium circinatum

radiataPitch canker causes cankers/necrotic areas of bark on the main stem and lateral branches of affected trees. Pitch may stream from cankers. The cankers cause top kill and branch dieback. Flagging of branch...

Pitted sap rot, purple conk
Trichaptum abietinum

trichaptum_abietinumThe fruiting bodies (conks) have a purple lower surface. They are 1-3 cm wide with an upper surface which is grey and hairy.

Red fomes rot
Fomitopsis cajanderi

This wood decay forms perennial, woody, bracket-like to hoof shaped conks on the trunk of affected trees. The upper surface is brown to black, cracked and rough. The lower surface has small circular pore...

Schweinitzii Butt Rot
Phaeolus schweinitzii

Phaeolus_schweinitziiThe annual fruiting bodies most commonly form on the ground around affected trees in the late summer. They have a spongy, leathery texture and appear shelf-like on the stem and stipitate when growing on t...

Sudden Oak Death
Phytophthora ramorum

AerialPhytophthora ramorum causes two types of symptoms on affected plants. In some it causes bleeding cankers on the mainstem with red-brown exudate. Zone lines are present around diseased tissue when bark is ...

Black pineleaf scale
Nuculaspis californica

Nuculaspis_californicaOutbreaks of black pineleaf scale are often associated with smog and dust. The insect feeds only on the needles and is yellowish-brown to black and broadly oval in outline. The injured needles turn yello...

Carpenter ant
Camponotus spp.

adultCarpenter ants tunnel in the wood of stumps, logs, and standing dead trees. They are black or black and red and are 7 to 15 mm long. They do not eat the wood, feeding mostly on other insects. They have ...

Douglas fir beetle
Dendroctonus pseudotsugae

frassThe Douglas-fir beetle often kills trees in small groups. Many times these trees are weakened by fire, drought, dwarf mistletoe, rust, or smog. Generally only trees over 6 inches in diameter will be atta...

Douglas-fir tussock moth
Orgyia pseudotsugata

orgyia_pseudotsugataThe Douglas-fir tussock moth prefers Douglas-fir and white fir in California, but will attack other firs and pines when mixed with the preferred hosts. The adult is a dull brownish-gray moth and the femal...

Flatheaded Fir Borer
Melanophila drummondi

topkill"Flatheaded fir borers commonly breed in felled trees or those weakened by fire, defoliation, drought, or other types of disturbance. Trees infested are usually pole size or larger. Beetles can infest the ...

Spruce spider mite
Oligonychus ununguis

Oligonychus_ununguisThe spruce spider mite feeds on foliage. It is a common pest of ornamentals and thrives under hot, dry conditions. The adults are green, pink, or brown and occur mostly on older needles. Needles first a...