Tree Pests

From the Report:

"Spruce Beetle (Dendroctonus rufipennis) Acres affected in 2019: 16,000 of highelevation Englemann spruce forest At first glance, estimates seem to point to spruce beetle activity slowing in the Southeast Area after 22,800 acres were affected there in 2018. However, aerial detections were difficult last year, as heavy snowpack persisted later than usual, delaying tree symptoms by more than three weeks, which might explain some of the decline in acres affected. In 2019, 41 percent of the acres targeted by spruce beetle (nearly 6,500 of 16,000 acres) were in locations previously unaffected by the current outbreak, indicating this pest is still moving into new areas. Active populations are currently disturbing high-elevation forests west of Antero Reservoir and Thirtynine Mile Mountain in Park County, as well as the Blanca Peak area in Huerfano County. More than 38 percent of the Southeast Area’s highelevation Engelmann spruce-fir forest has been affected by spruce beetle since 1996.

 

Douglas-fir Beetle (Dendroctonus pseudotsugae) Acres affected in 2019: over 1,100 Douglas-fir beetle primarily targeted new forested acres not impacted in prior surveys in 2019. Nearly all 1,100 acres were previously unaffected by the current outbreak. Since 1996, approximately 7 percent of the Southeast Area’s mixed-conifer forests that hold Douglas-fir have been affected by this pest. Groups of tree-kill affected the northern Sangre de Cristo Mountains in Fremont County and groups of Douglas-fir trees in the Wet Mountains. Douglas-fir beetle continues to cause group tree mortality in El Paso County as a result of weakened trees after a Douglas-fir tussock moth outbreak.

 

Mountain Pine Beetle (Dendroctonus ponderosae) Acres affected in 2019: 28 A native bark beetle, the mountain pine beetle infests all pine species naturally found in Colorado, except for piñon. Populations reproduce once every year, requiring new, live trees for this beetle to complete development. Adults fly to green trees typically from late June into early August in Colorado, where they lay their eggs inside the bark. Aside from localized activity, populations remain at endemic – or baseline – levels across the state. Areas in the Taylor River drainage experienced increased lodgepole pine tree mortality in 2019, but overall the 28 acres affected across the Southeast Area were far fewer than the 115 acres detected in 2018. Most of the additional affected areas are high-elevation, five-needle pines within the Sangre de Cristo Range.

 

Western Balsam Bark Beetle/ Root Disease Complex Acres affected in 2019: 154 Small groups of high-elevation subalpine fir trees died on 154 acres in the Southeast Area in 2019. Locations affected by western balsam bark beetle (Dryocoetes confusus) may vary from year to year, though they are typically relatively low in intensity when there aren’t drought conditions to make trees more susceptible to this pest.

 

Western Spruce Budworm (Choristoneura freemani) Acres affected in 2019: 20,000 In 2019, acres affected by western spruce budworm were down from 2018, when insects fed on trees across about 37,700 acres. Activity continues in the Wet and Sangre de Cristo mountains and between McKenzie Junction and Rye, on the Highway 165 corridor. Park and Teller counties also continue to be affected, as in years past."