Tackling Russian Knapweed Biocontrol with New Tools in Riparian Areas
Joseph Milan1* and Jennifer Andreas2
1Bureau of Land Management, Boise, ID, USA; jmilan@blm.gov
2Washington State University Extension, Puyallup, WA, USA, jandreas@wsu.edu
A reduction in Tamarix following the release of Diorhabda sp. beetles has been documented throughout much of the invasion of Tamarix where establishment of the beetles has occurred. The destruction of this invasive plant is well documented, as is the change in soil structure of tamarisk-dominated soils. Several invasive species, namely Russian knapweed (Rhaponticum repens) and downy brome (Bromus tectorum), are benefitted by these changes in soil salinity among other environmental factors. These secondary invasives are an impediment to the pursuit of an ecological recovery of riparian sites previously dominated by tamarisk. While there are no current classical biological control options for downy brome, there are two approved biological control agents for Russian knapweed (Jaapiella ivannikovi and Aulacidea acroptilonica) that have demonstrated impacts, especially in riparian areas. This presentation will focus on establishment factors and impact of these two biological control agents.