1. Forest Health Management International
Forest Health Issues By
William M. Ciesla
Forest Health Management International
Forest Collins, CO
Progreen Expo

2. Today’s Program Bark beetles Conifer defoliators Broadleaf defoliators
Forest diseases
Emphasis – how to recognize pest agent and its damage

3. Bark beetles (Coleoptera:Curculionidae:Scolytinae)
Adult
Larva

4. Major bark beetle pests of Colorado’s forests
Common Name
Scientific name
Host tree(s)
Mountain pine beetle
Dendroctonus ponderosae
Limber, lodgepole, ponderosa pines
Spruce beetle
D. engelmannii
Engelmann spruce
Douglas-fir beetle
D. pseudotsugae
Douglas-fir
Western pine beetle
D. brevicomis
Ponderosa pine
Pinyon ips
Ips confusus
Pinyon pine
Fir engraver
Scolytus ventralis
White fir
Western balsam bark beetle
Dryocoetes confusus
Subalpine fir

5. Pitch tubes are an indicator of host resistance
Mass Attack
Pitch tubes are an indicator of host resistance

6. Bark beetle galleries are distinct
Douglas-fir beetle
Fir engraver beetle
Mountain pine beetle
Pinyon ips.

7. Blue stain fungi introduced by bark beetles

8. Mountain pine beetle, Dendroctonus ponderosae

9. All native pines except pinyon are hosts of MPB
Lodgepole pine
Ponderosa pine
Limber pine

10. MPB damage in ponderosa and lodgepole pines

11. Mountain pine beetle infestations – 1996-2016
Cumulative area of damage = 3.4 million acres
Mountain pine beetle infestations –

12. Mountain pine beetle – 2013 (98,000 acres)

13. Aftermath of a mountain pine beetle outbreak

14. Mountain pine beetle attack in an urban area

15. Mountain pine beetle management
Brood destruction
Preventative sprays
Anti-attractants
Forest Management

16. Spruce Beetle, Dendroctonus rufipennis
Eggs
Pupa
Immature adults
Adult

17. Spruce beetle galleries

18. Windthrow – Sangre de Cristo Range

19. Spruce beetle “faders”

20. Spruce beetle infestations – 2000-2016
Cumulative area of damage = 1.7 million acres
Spruce beetle infestations –

22. Douglas-fir beetle, Dendroctonus pseudotsugae
Aerial view of damage
Galleries

23. Pinyon ips, Ips confusus
Adults
Damage
Galleries
Damage

24. Fir engraver beetle, Scolytus ventralis
Aerial view of damage
Host tree – white fir, Abies concolor
Galleries

25. Underlying causes of bark beetle outbreaks
Condition of the forest
Mature/overmature forests
Overstocked forests
Fresh windthrow
Wildfire
Outbreaks of defoliating insects
Climatic factors
Drought/excess precipitation
Mild winter temperatures
Climate change?

26. Western spruce budworm, Choristoneura freemani
Larvae
Pupa
Adult

27. Defoliation by western spruce budworm

28. Douglas-fir tussock moth, Orgyia pseudotsugata
Larva
Pupa
Adult female/egg mass
Adult male

29. Douglas-fir Tussock Moth (DFTM)
Outbreaks
Outbreaks are cyclic – occur at 7-10 year intervals
Duration – 1-3 years
Outbreaks typically collapse due to a virus infection
An outbreak in occurred CO between
Defoliation detected in 2014
Major outbreak – 2015, collapsed 2016

30. Douglas-fir tussock moth, Rampart Range - 2015

31. Douglas-fir tussock moth, Perry Park, 28 June 2015

32. Tussockosis due to exposure to DFTM larval hairs

33. DFTM activity in 2015 – 26,000 acres
Boulder
Denver
Colorado Springs
DFTM activity in 2015 – 26,000 acres

34. DFTM pupal cases and egg masses on building

35. Pine sawflies, Neodiprion spp, Zadiprion spp.
Larvae
Pupae
Eggs
Adult Male
Adult female

36. Light defoliation by Neodiprion autumnalis, Elbert Co.

37. Heavy defoliation by Neodiprion autumnalis, Elbert Co. - 2014

38. Same stand - August 2015

39. Bull pine sawfly, Zadiprion townsendi, Stove Prairie

40. Defoliators of Aspen

41. Western tent caterpillar, Malacosoma californicum

42. Western tent caterpillar, Life stages
Egg
Larva
Pupa
Adult

43. Other host plants of western tent caterpillar
Mountain mahogany
Wild currant
Bitterbrush
Choke cherry
Gambel oak
Other woody plants

44. Large aspen tortrix, Choristoneura conflictata
Larva
Rolled leaf
Pupa
Adult

45. Defoliators of Gambel oak and other woody plants

46. Fall cankerworm, Alsophila pometaria, life stages
Egg
Larva
Adult - male
Adult - female

47. Defoliation of Gambel oak by fall cankerworm near Castle Rock

48. Oak leaf roller
Archips semiferanus

49. Effects of Forest Defoliation
Defoliation is unsightly
Large numbers of larvae can be a nuisance
Growth loss
Branch dieback or top kill
Tree death (usually following successive defoliation)

50. Tree mortality due to DFTM– northern Rampart Range

51. Aspen mortality following 7 years of WTC defoliation
North Purgatory River Basin

52. Management of Forest Defoliators
Larvae of moths and butterflies are susceptible to Bacillus thuringiensis (Bt)
Sawfly larvae are not susceptible to Bt -use chemical insecticides (malathion, Orthene, Permethrin, Sevin, Warrior [Lambda-cyhalothrin])
Timing is critical for control of forest defoliators
Aerial vs. ground spraying

53. Caterpillars vs. Sawflies
Caterpillars: 5 or fewer prolegs
Sawflies: 6 or more prolegs

54. Timing of application is critical
Apply spray after egg hatch
Not when larvae are mature
Desired result
Not this

55. Aspen discoloration, Bull Mountain

56. Marssonina leaf blight of aspen

57. Dwarf mistletoes, Arceuthobium spp.
A. americanum – Lodgepole pine
A. vaginatum – Ponderosa pine
A. douglasii – Douglas-fir
A. cyanocarpum – Limber pine
Dwarf mistletoes, Arceuthobium spp.

58. Witches brooms caused by dwarf mistletoe infection

59. Damage caused by dwarf mistletoes
Deformity
Growth loss
Tree mortality
Increased susceptibility to bark beetle attacks

60. Dwarf mistletoe management
Timely harvesting of infected stands
Removal of infected regeneration

61. Questions, comments?

62. Thank you for your attention Gracias por su atencion
The End
Thank you for your attention
Gracias por su atencion