Presentation by Karl Puls of the Oregon Department of Agriculture discussing pest of Christmas trees. From June 2013

1. Current insects and diseases
of concern in
Christmas trees
By Karl Puls
Oregon Department
of
Agriculture

2. Useful tools
• Pruners
• Knife
• Hand lens
• Camera
• Beating cloth
• Clip board
• Shovel
• Chain saw

3. Pests of
True firs
Many pests feed on the
underside of needles and
branches or the interior of
the tree

4. 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.

5. C. occidentalis
attacks older
woody growth, not
current season
growth or needles.
It feeds at the base
of needles

6. Cinara aphids
on Noble fir
Cinara occidentalis

7. Cinara aphids at
base of needles
Noble fir

8. Cinara sp.
Syrphid fly larva
feeding on aphids
C. occidentalis
on Fraser fir
Cinara sp.
ces.ncsu.edu

9. C. occidentalis damage
with sooty mold
Noble fir

10. Balsam twig aphid
on 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.

11. Balsam Twig Aphid
Damage
Mindarus abietinus on Grand fir

12. Balsam Twig Aphid
on grand fir
Mindarus abietinus

13. Root Aphids
Prosiphilus 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.

14. 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?

15. Root aphids on
Noble fir
Prosiphilus americanus

16. Balsam woolly adelgid
Adelges piceae
eol.org

17. Balsam woolly
adelgid
• 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

18. Balsam woolly adelgids
feeding on trunk
Adelges piceae

19. Balsam Woolly Adelgid
damage in Balsam fir
Adelges piceae

20. Treat BWA in
June when
crawlers are
active
Adelges piceae

21. 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.

22. Cooley spruce gall
adelgid crawlers in Spring
Adelges cooleyi

23. Cooley Spruce Gall Adelgid
adults form protective coating
Adelges cooleyi

24. Douglas Fir
Needle Midge
Contarinia sp.

25. • 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

26. Douglas fir
Needle midge
larva
Forestry Images.
Contarinia spp.
Goheen & Wilhite 2006.

27. 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.
Adult
Furniss 1942.
1 mm
Larva

28. Douglas fir
Twig 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).

29. Galleries caused by DFTW in
Douglas fir branches
Forestry images.
Oregon Dept. Agriculture.
Oregon Dept. Agriculture.
Oregon Dept. Agriculture.

30. DFTW Damage
Forestry images.
Furniss 1942.

31. Diseases of Douglas fir and True fir
Sunburn on noble fir

32. Phytophthora Root Rot

33. Phytophthora root rot

34. Phytophthora root rot

35. Diagnosing Phytophthora
root rot

36. Phytophthora root rot
management
• Reduce by improving drainage
• Remove effected trees
• Clean pruning equipment when dealing with
effected trees.
• Plant resistant species

37. Annosus root rot
Heterobasidion annosum
Chain saw diagnosis

38. Swiss Needle Cast

39. Swiss Needle Cast
Chal Landgren

40. Swiss needle cast
on 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

41. Swiss Needle Cast
Chal Landgren

42. Rhabdocline needle cast

43. Rhabdocline needle cast

44. Rhabdocline needle cast

45. Swiss and Rhabdocline needle cast

46. Uredinopsis rust on Grand Fir

47. Uredinopsis pustules on Grand Fir

48. 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

49. Christmas Tree Diseases,
Insects & Disorders in
the Pacific Northwest:
Identification and
Management,
Editor- Gary Chastagner
-Washington State
University Extension
Excellent descriptions
and images of pests and
other types of damage.

50. Christmas Tree Diseases, Pests
and Other Disorders- Luisa
Santamaria and Chal Landgren
- Oregon State University
Extension
Excellent field guide, images,
descriptions and waterproof
Pages
Online link: SERFcertified.org
Look under ‘farm resources’

51. Knowledge is power