Elaeagnus angustifolia (Russian olive)

Control is difficult once E. angustifolia trees are mature and populations are well-established, or may even be nearly impossible to eradicate, though Zouhar (2005) thoroughly review management and control methods employed in the USA, which are largely adapted and reported here. Mowing seedlings, cutting, burning, spraying (Diesburg, 1994; Geyer and Long, 1994), girdling and bulldozing have all been attempted, although cutting, followed by either spraying or burning the stumps is the most effective (Olson and Knopf, 1986b).

Zouhar (2005) suggested that it is unlikely that exotic species will be eradicated from riparian systems in the south-west USA, and that it is also unlikely that simply removing exotics would allow natives to thrive where conditions no longer favour them. Thus, if a return to natural, sustainable conditions may not be possible then it may be necessary to design management techniques such as timed interval flooding and artificial seedbeds, to maintain riparian function. In conclusion for the south-west USA, managing for native species may be more successful than managing against exotic species. Promotion of natural processes such as natural flooding regimes may be important in managing for desirable native species. However, removal of E. angustifolia may only facilitate recovery of native species where natural disturbance processes still function adequately (Zouhar, 2005). On dammed, regulated rivers and areas with intensive livestock grazing, removal or suppression of E. angustifolia will only have temporary effects unless native species are established. Elimination of the stresses such as high salinity and reduced stream flows, that favour exotic plants over native plants may be necessary if native plant communities are to be sustained (Zouhar, 2005).

Hand-pulling and other manual methods have been attempted with limited success in Arizona, USA (Landis et al., 2006), and ring-barking will also kill older trees (Zouhar, 2005). Also, techniques such as mowing, cutting, girdling, chaining, and bulldozing can suppress E. angustifolia. However, disadvantages can be substantial, including the need for frequent treatment repetition, indiscriminate removal of other species, and severe soil disturbance.

CABI initiated a biological control programme against E. angustifolia in 2007, with the primary focus on species that impact the reproductive output without affecting standing trees, due the potential conflict of interest (Weyl et al., 2017). Of the three species currently under study, the Eriophyid mite, Aceria angustifoliae, is the most promising agent with a high level of specificity and preliminary studies suggest a high impact on fruit and ultimately seed production (Weyl et al., 2017). However, to date no biological control agents have been released against this species.

Due to the variable regulations around (de-)registration of pesticides, we are for the moment not including any specific chemical control recommendations. For further information, we recommend you visit the following resources: