Forest Health Issues By William M Ciesla Forest Health Management International Forest Collins CO Progreen Expo 2018 Todays Program Bark beetles Conifer defoliators Broadleaf defoliators Forest diseases ID: 767512
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Forest Health Issues By William M. Ciesla Forest Health Management International Forest Collins, CO Progreen Expo - 2018
Today’s Program Bark beetles Conifer defoliators Broadleaf defoliators Forest diseases Emphasis – how to recognize pest agent and its damage
Bark beetles ( Coleoptera:Curculionidae:Scolytinae ) Adult Larva
Common Name Scientific name Host tree(s) Mountain pine beetle Dendroctonus ponderosaeLimber, lodgepole , ponderosa pinesSpruce beetle D. engelmannii Engelmann spruce Douglas-fir beetle D. pseudotsugae Douglas-fir Western pine beetle D. brevicomisPonderosa pinePinyon ipsIps confususPinyon pineFir engraverScolytus ventralisWhite firWestern balsam bark beetleDryocoetes confususSubalpine fir Major bark beetle pests of Colorado’s forests
Mass Attack Pitch tubes are an indicator of host resistance
Bark beetle galleries are distinct Mountain pine beetle Douglas-fir beetle Pinyon ips . Fir engraver beetle
Blue stain fungi introduced by bark beetles
Mountain pine beetle, Dendroctonus ponderosae
All native pines except pinyon are hosts of MPB Lodgepole pine Ponderosa pine Limber pine
MPB damage in ponderosa and lodgepole pines
Mountain pine beetle infestations – 1996-2016 Cumulative area of damage = 3.4 million acres
Mountain pine beetle – 2013 (98,000 acres)
Aftermath of a mountain pine beetle outbreak
Mountain pine beetle attack in an urban area
Mountain pine beetle management Preventative sprays Anti-attractants Brood destruction Forest Management
Spruce Beetle, Dendroctonus rufipennis Eggs Pupa Immature adults Adult
Spruce beetle galleries
Windthrow – Sangre de Cristo Range
Spruce beetle “faders”
Spruce beetle infestations – 2000-2016 Cumulative area of damage = 1.7 million acres
Douglas-fir beetle, Dendroctonus pseudotsugae Galleries Aerial view of damage
Pinyon ips , Ips confusus Adults Damage Damage Galleries
Fir engraver beetle, Scolytus ventralis Galleries Aerial view of damage Host tree – white fir, Abies concolor
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?
Western spruce budworm, Choristoneura freemani Pupa Adult Larvae
Defoliation by western spruce budworm
Larva Pupa Adult male Adult female/egg mass Douglas-fir tussock moth, Orgyia pseudotsugata
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 2004-2008 Defoliation detected in 2014 Major outbreak – 2015, collapsed 2016
Douglas-fir tussock moth, Rampart Range - 2015
Douglas-fir tussock moth, Perry Park, 28 June 2015
Tussockosis due to exposure to DFTM larval hairs
Denver Colorado Springs Boulder DFTM activity in 2015 – 26,000 acres
DFTM pupal cases and egg masses on building
Pine sawflies, Neodiprion spp , Zadiprion spp. Larvae Pupae Adult female Adult Male Eggs
Light defoliation by Neodiprion autumnalis , Elbert Co.
Heavy defoliation by Neodiprion autumnalis , Elbert Co. - 2014
Same stand - August 2015
Bull pine sawfly, Zadiprion townsendi , Stove Prairie
Defoliators of Aspen
Western tent caterpillar, Malacosoma californicum
Western tent caterpillar, Life stages Egg Larva Pupa Adult
Other host plants of western tent caterpillar Mountain mahogany Wild currant Bitterbrush Choke cherry Gambel oak Other woody plants
Large aspen tortrix , Choristoneura conflictata Larva Rolled leaf Pupa Adult
Defoliators of Gambel oak and other woody plants
Fall cankerworm, Alsophila pometaria , life stages Egg Larva Adult - male Adult - female
Defoliation of Gambel oak by fall cankerworm near Castle Rock
Oak leaf roller Archips semiferanus
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)
Tree mortality due to DFTM– northern Rampart Range
Aspen mortality following 7 years of WTC defoliation North Purgatory River Basin
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
Caterpillars vs. Sawflies Caterpillars: 5 or fewer prolegs Sawflies: 6 or more prolegs
Timing of application is critical Apply spray after egg hatch Not when larvae are mature Desired result Not this
Aspen discoloration, Bull Mountain
Marssonina leaf blight of aspen
Dwarf mistletoes, Arceuthobium spp. A. americanum – Lodgepole pine A. vaginatum – Ponderosa pine A. douglasii – Douglas-fir A. cyanocarpum – Limber pine
Witches brooms caused by dwarf mistletoe infection
Damage caused by dwarf mistletoes Deformity Growth loss Tree mortality Increased susceptibility to bark beetle attacks
Dwarf mistletoe management Timely harvesting of infected stands Removal of infected regeneration
Questions, comments?
The End Thank you for your attention Gracias por su atencion