Quaking Aspen Insect Defoliation & Aspen Canker Erin Redding Photo: Unknown
Ecological Importance www.bentler.use Photo by Dwight Phillips Photo by M. & J. Stouffer www.fortliard.com/climate Photo: Clipart.com
Economical Importance Crates Pallets Matchsticks Tongue depressors Ice cream spoons Furniture House trim Animal bedding Saunas Photo by Tim Morris Fergus, 2005
Quaking Aspen Populus Tremuloides Most widely distributed tree in North America. Can survive temperatures between - 57 C and 41 C (Perala and Carpenter, 1985). Little (1971)
Pioneer species Fast growing Shade intolerant Short life span Found on disturbed sites Sandy or gravelly soils Quaking Aspen Populus Tremuloides USDA Plant Profile
Flowering Flowers bloom in mid-spring before leaf-out Trees are usually dioecious Flowers are wind pollinated Image from DeByle, Norbert V and Robert P. Winokue, ed. 1985. Aspen: Ecology and management in the western United States. USDA Forest Service Gerenal Technical Report RM 119, 283p.
Seedling Establishment Seeds are wind dispersed Germination can occur between 2 C and 30 C (McDonough, 1979) Germination does not depend on light (Faust, 1936 as cited by Barnes 1966) Rootlets cannot break through leaf litter. Seeds will only survive if they fall on bare soil (Fergus, 2005). Photo bytree NM Female Catkin Photo by B. Campbell
Root Sprouts More common and more successful than reproduction by seed New shoots grow from parent root systems Vegetative reproduction creates large clones Clones can live for thousands of years Individual id trees in a clone are equally genetically predisposed to biotic stressors (Barnes, 1966; Fergus, 2005) PANDO Fishlake National Forest, Utah
Competitors Without frequent disturbance, aspen are replaced by trees with longer lifespan and/or more shade tolerance. Forest fire keep aspen from being outcompeted
Insect Defoliation Photo by S Katovich
Lepidoptera Native to North America Generalist Herbivore Forest Tent Caterpillar Malacosoma disstria Quaking aspen, Oaks (Quercus spp.), Gums (Nyssa spp. and Liquidambar styraciflua) (Meeker, 2008) Eat buds, flowers, and foliage Photo by G. McIlveen, Jr.
Life Cycle of Forest Tent Caterpillar
Egg masses 100 to 350 eggs Form band up to 2.5cm long Overwintering stage Hatch mid-february to April 5 instars Photo by Jeffrey Lotz Mature Larvae Dark gray to brownish black Sparse white hairs Pale blue lines 5 to 6.4 cm Photo by JD J.D. Harper Photo by James R. Meeker Spin cocoons of silk in folded leaves Transformation takes 10 days Adult moth Tan to brown Dark lines through forewings 2.5 to 4.5 cm Late Spring Live 1 day to 2 weeks Meeker, 2008; Batzer and Morris, 1978 Photo by Jeffrey Lotz
Impact on the Tree Re-flush smaller, fewer leaves Branch dieback Crown thinning Less carbohydrate storage Loss of vigor More susceptible to 2 stress agents Death Photo by godurango.com Gregory and Wargo, 1986 as cited by Fitzgerald, 1995, 226
Predisposing Factors FTC is a native insect Many native parisitoids Pest can survive temperatures t between - 40 C and 38 C (Batzer and Morris, 1978). Forest fragmentation and edge effects Faster development of outbreaks Outbreaks last longer Photo by J.D. Harper (Roland, 1993)
Inciting Factors Outbreaks lasting several years Tree loses too much vigor to respond to environment as adapted
Contributing Factors Drought Insect borers Fungi Hypoxylon (canker) Nectria (canker) Fomes (stem decay)
Control Options Preemptive Maintain vigorous growth Do not grow aspen in fragmented stands Minimize other stresses Reactive Do nothing Physical Removal Pesticides Bacillus thuringiensis Biological Control Entomophaga
Aspen Canker Photo by na.fs.fed.us
Hypoxylon mammatum Ascomycota Found throughout the range quaking aspen Canker rot fungus Photo by William Jacobi
Life Cycle of Hypoxylon y mammatum (Probably )
Wind or water borne ascospores enter tree through wounds Infect living tissue underneath bark Ascospore (sexual spores) are produced in perithecia Brown to black and very small 5-14 months of infe ection Conidia (asexual spores) are produced d Gray and powdery Photos from Anderson and Anderson, 1979
Impact on the Tree Yellow sunken areas Canker made up of dead d cells Girdling of conductive tissue More susceptible to 2 stress agents Death Papery bark covering hyphal pegs Photo by USDA Forest Service Archive, bugwood.org Anderson and Anderson, 1979
Predisposing Factors Insect tunnels Wounds Open stand structure Soil quality Water stress Age 15-40 years old High humidity and low temperatures Photo by Echo Thomsen Photo by William Livingston
Inciting Factors Canker girdles enough of the transport tissue to disrupt total tree Canker girdles enough of the transport tissue to disrupt total tree functioning
Contributing factors Secondary fungal infections Wind Anderson and Anderson, 1979
Control Options Do nothing Harvest stand early if 15-25% infected Allow aspen to grow back Harvest stand immediately if > 25% infection Grow a different species Conservative thinning Photo by William Jacobi Anderson and Anderson, 1976
Health Management Plan for Quaking Aspen Preemptive Strategies Grow quaking aspen on sites that it is adapted to Do not grow in open or fragmented stands Avoid thinning stress Monitor and Survey Monitor population patterns of FTC Egg counts Look for signs of fungal infection Reactive Strategies Remove individuals infected with H. mammatum, possibly whole stands Leave genetically resistant clones whenever possible Pesticides id B.T.
References Anderson, Ralph L. and Gerard W. Anderson. 1979. Hypoxylon Canker of Aspen. Forest Insect & Disease Leaflet 6, US Department of Agriculture Forest Service, Washington, D.C. Batzer, Harold O. and Robert C. Morris. 1978. Forest Tent Caterpillar. Forest Insect & Disease Leaflet 9, US Department of Agriculture Forest Service. Fergus, Charles. Trees of New England. Falcon Guide. Guilford. 2005. pp.14-22. Fitzgerald, Terrance D. The Tent Caterpillars. Cornell University Press. Ithaca. 1995. Little, E.L., Jr., 1971. Atlas of United States trees, volume 1, conifers and important hardwoods: U.S. Department of Agriculture Miscellaneous Publication 1146, 9 p., 200 maps. McDonough, Walter T. Sexual Reproduction, Seeds, and Seedlings. Meeker, James R. 2008. Forest Tent Caterpillar, Malacosoma disstria Hubner (Insecta: Lepidopter: Lasiocapidae) University of Florida IFAS Extension. Perala, D.A., Carpenter, E.M. 1985. Aspen: An American Wood. FS 217. Washington, DC: U.S. Department of Agriculture, Forest Service. p 1 4122 Roland, Jens. 1993. Large-scale forest fragmentation increases the duration of tent caterpillar outbreak. Pecologia 93: 25-30. USDA Plants Profile http://www.fs.fed.us/wildflowers/communities/aspen/grow.shtml Photo by godurando.com
Questions? Photo by Anonymous