2014 Colorado Forest Insect and Disease Update 2014 Colorado Forest Insect and Disease Update A supplement to the 2014 Report on the Health of Colorado’s Forests Acknowledgments Special thanks to the following Colorado The following individuals reviewed and/ The following individuals served on State Forest Service (CSFS) State Office or provided information for the aerial the report work group and/or provided personnel for providing leadership and/or survey results presented in this report: information, guidance and technical content and photos in the production of review: this report: • Justin Backsen, Aerial Surveyor, USDA Forest Service, Lakewood, • Robert Cain, Entomologist, USDA • Pete Barry, GIS Technician Colo. Forest Service, Lakewood, Colo. • Joseph A. Duda, Deputy State • Kelly Burns, Forest Pathologist, • Whitney Cranshaw, Professor and Forester USDA Forest Service, Lakewood, Extension Specialist, Bioagricultural • Ryan Lockwood, Public and Media Colo. Sciences and Pest Management, Relations Coordinator • Ron Cousineau, District Forester, Colorado State University, Fort • Lisa Mason, Outreach Forester Granby District, CSFS, Granby, Colo. Collins, Colo. • Susan Matthews, Forest Management • Meg Halford, Assistant District • Roy Mask, Assistant Director of Division Supervisor Forester, Franktown District, CSFS, Forest Health Protection, USDA • Kim, Mueller, Outreach Division Franktown, Colo. Forest Service, Lakewood, Colo. Supervisor • Justin Hof, Forestry Technician, • S. Sky Stephens, Entomologist, • Dan West, Entomologist USDA Forest Service, Lakewood, USDA Forest Service, Lakewood, Colo. Colo. Thanks to William M. Ciesla, Forest • Brian Howell, Aerial Survey Program • Keith Wood, Community Forestry Health Management International, Manager, USDA Forest Service, Program Manager, Forest Fort Collins, Colo., for his Lakewood, Colo. Management Division, CSFS, contributions as an author and • Benjamin Pfohl, Assistant District Broomfield, Colo. photographer in the development of Forester, Boulder District, CSFS, • Mitch Yergert, Director, Plant this report. All photos by William M. Boulder, Colo. Industry Division, Colorado Ciesla unless otherwise noted. • Rebecca Powell, Entomologist, Department of Agriculture, USDA Forest Service, Lakewood, Broomfield, Colo. Colo. • Kelly Rogers, District Forester, Grand Junction District, CSFS, Grand Junction, Colo. • Jennifer Ross, Geographic Information Systems Specialist, USDA Forest Service, Monument, Colo. • Michael Till, Assistant District Forester, Woodland Park District, CSFS, Woodland Park, Colo. Front and back cover photo: William M. Ciesla Background photo this page: Bill Cotton, Colorado State University 2014 Colorado Forest Insect and Disease Update 1 The CSFS also produces an annual report on the health of Colorado’s forests, which provides information to the Colorado General Assembly and citizens about emerging and ongoing forest health issues, as well as actions the agency is taking to reduce their impacts. This report is a supplement to the 2014 Report on the Health of Colorado’s Forests, which is available online at www.csfs. colostate.edu. Forest Insect and Disease Highlights • For the third successive year, Colorado’s most widespread and damaging forest insect pest was spruce beetle. A total of 485,000 acres with active infestation were observed in high- ▲ Meg Halford, CSFS Franktown District assistant district forester, talks with landowners elevation Engelmann spruce forests throughout the state. about the results of an aerial survey to map pine sawfly defoliation. • Mountain pine beetle infestations continued to decline following a massive outbreak that impacted nearly 3.4 million Introduction acres of Colorado forests between 1996 and 2013. In 2014, only Forest insects and diseases represent an integral part of the 15,000 acres with active infestation were mapped. Most of the dynamics of Rocky Mountain ecosystems. Bark beetle outbreaks, damage occurred in Larimer County. for example, can beneficially eliminate most of the older host trees • Stands of mature Douglas-fir continued to be attacked and over extensive areas of mature forests, which sets the stage for the killed by Douglas-fir beetle in the southern portions of the state. development of young, more vigorous forests. However, large-scale Approximately 34,000 acres were affected in 2014. outbreaks also can devastate forests critical for timber production, • Western balsam bark beetle and root disease fungi, which are wildlife habitat, recreation and clean water supplies. responsible for a complex known as “subalpine fir decline,” Monitoring forests to assess the status of damaging insects, continued to cause tree mortality in high-elevation subalpine fir diseases and other pests is an integral part of forest management. forests. Approximately 173,000 impacted acres were mapped. In Colorado, the primary source of data on current pest conditions • White fir continued to be attacked and killed by the fir engraver is the annual aerial forest health survey – a cooperative program beetle. Damage was mapped on 43,000 acres in 2014. involving personnel from the USDA Forest Service and the • Western spruce budworm defoliated 178,000 acres of Douglas- Colorado State Forest Service (CSFS). fir, white fir and spruce forests in southern Colorado. Damage Aerial forest health surveys provide information on location was seen as far north as portions of the Rampart Range. and intensity of damage that forest landowners can use to manage • Douglas-fir tussock moth reached epidemic levels on the slopes forest pests. Trained observers fly in small aircraft (e.g., Cessna 206 of Cheyenne Mountain and in the Rampart Range. Ornamental and/or Cessna 210) and map the location of the current year’s forest blue spruce trees also were defoliated in several Front Range damage. Data are recorded on touch-screen computers containing communities, and large numbers of this pest’s larvae were seen mapping software. An interface with a GPS displays the location in a forested community west of Boulder. and track of the survey aircraft. Resulting data are transmitted daily • A species of pine sawfly caused severe defoliation of ponderosa to a central location, where a geographic information system (GIS) pine on 7,400 acres in Elbert and northern El Paso counties. specialist analyzes and summarizes the data. Some areas detected • Western tent caterpillar and large aspen tortrix caused during the aerial survey are later ground-checked to verify the defoliation of a combined 78,000 acres of aspen forests. agent responsible for the damage and the level of severity. • Thousand cankers disease, transmitted by the walnut twig Other sources of information on the status of the state’s forests beetle, continued to kill ornamental black walnuts in many are field visits made by CSFS foresters. These visits help foresters Colorado communities. In 2014, this disease was detected as far identify forest pest activity while advising private landowners in the east as Fort Morgan. management of their forests, managing state-owned forestlands and conducting forest inventories. In addition, the CSFS, in cooperation with the Colorado Department of Agriculture, USDA Animal and Plant Health Inspection Service (APHIS), USDA Forest Service and other groups, conducts special surveys to ensure early detection of invasive species. 2 Exotic Pest Highlights • Grand Mesa – Infestations continue in mature spruce forests throughout the area. • Emerald ash borer (EAB), an insect native to Asia that has killed • Mount Zirkel/Rabbit Ears Range – Infestations here, which millions of North American ash trees, was detected in the City are the result of a 1997 blowdown event in the Mount Zirkel of Boulder in 2013. A special survey, designed to delimit the Wilderness Area, continue in the Rabbit Ears Range west of area of infestation, confirmed the pest in 10 contiguous square Rocky Mountain National Park. miles in Boulder. Surveys in portions of several other Front • Sangre de Cristo Range – Infestations intensified significantly Range communities in 2014 did not confirm the presence of over much of the range in 2014. Most high-elevation EAB. Engelmann spruce forests here now exhibit moderate to severe • No gypsy moths were trapped in a statewide trapping effort for levels of damage. the pest, a defoliator of primarily broadleaf trees. • San Juan/La Garita Mountains – Infestations intensified • Several limber pines infected with white pine blister rust were significantly in the Henson Creek Basin and in the mountains detected in the vicinity of Allenspark, extending the known surrounding Lake San Cristobal and the upper Lake Fork of northern distribution of this disease in Colorado. the Gunnison River near Lake City. This is now part of the northern front of an outbreak that was first detected in the Weminuche Wilderness in 2003. Large areas with moderate to Status of Forest Insects, Diseases severe damage were mapped here. Small groups of dead trees and Other Damaging Agents also were detected in spruce forests in several tributaries of the Indigenous Pests Little Cimarron and Cimarron River basins. Localized activity Conifer Forests has been seen in these areas since 2012, and appears to be intensifying. Spruce Beetle Infestations are continuing at moderate to severe levels (Dendroctonus rufipennis) in the extreme western portions of the Rio Grande Basin, Spruce beetle outbreaks continued across Colorado’s high-elevation near the headwaters of the Rio Grande River. However,