For Immediate Release: September 18, 2008

Contacts:     Dr. Dan Bean, Palisade Insectary Director (970) 464-7916

BLM and Palisade Insectary mark progress with Tamarisk beetles

Colorado Department of Agriculture’s Palisade Insectary and the BLM Grand Junction Field Office have seen a marked improvement in the riverbank habitat along the Colorado and Dolores Rivers after three years of releasing leaf beetles to combat the invasive tamarisk tree.

The Palisade Insectary has collected and cared for beetles, conducted the releases, and completed the applied science and applied research in this partnership. The research findings will improve the effectiveness of future beetle releases throughout the state by determining the best times of year, temperatures, and even time of day to release the beetles.

Currently, tamarisks have been completely defoliated from Gateway to the state line on the Dolores River, and beetles can be found wherever there is tamarisk from McPhee Reservoir to the Utah state line. On the Colorado River, this is the first year of major defoliation in Ruby Canyon west of Loma, and there are large populations of beetles from Loma to the state line.

"I'm very pleased by this success and looking forward to helping more communities in western Colorado utilize biocontrol for tamarisk management" says Dr. Dan Bean, Director of the Palisade Insectary.

"The contrast between defoliated tamarisk (brown) and the green willows and cottonwoods is impressive. The beetles are finding every tamarisk plant, big or small," continues Sparky Taber, Grand Junction BLM Weed Management Specialist.

The BLM Grand Junction Field Office provided five initial release sites in western Colorado in 2005 (Mesa County), in consultation with the USDA Animal Plant Health Inspection Service, and provided the areas for the monitoring of tamarisk biocontrol to take place. Since 2005, Montrose BLM has also provided several sites along the Dolores River.

In 2009, the Insectary staff and BLM expect complete defoliation from Loma to the state line, and major beetle movement into the Grand Valley. Expect to see defoliated tamarisk turning brown by June of 2009. A defoliated tamarisk will re-sprout, but not to the previous extent, and the beetles will hit it again, which will further stress the plant.

Defoliation stresses the tamarisk, reducing competition with willows, cottonwoods and other desirable plants. Research in Lovelock, Nevada shows that once tamarisk is defoliated, transpiration (water use) is only 5% of pre-defoliation levels.

###