Natural biological mite seen as a viable means to slow or kill the invasive weed, to be deployed in British Columbia and Alberta in early 2023.
By Andrew Joseph, Farms.com; Image via CABI showing Aceria angustifoliae damage on the shoot tips of Russian olive weed.
This time, the invasion is the Russian olive weed that has become a scourge within Canada.
This short tree is a weed capable of surviving within dry conditions and cold temperatures, that drinks more water than native species in dry soil settings, which enables it to outgrow and even outcompete native plants.
Known as Elaeagnus angustifolia, the Russian olive aka silver berry, oleaster, or wild olive, is native to western and central Asia, Iran, from southern Russia and Kazakhstan to Turkey, parts of Pakistan and parts of India.
It was first introduced into North America in the early 1900s as a means to control soil erosion, sold by horticulture stores to customers who planted it to mark property edges, stabilize riverbanks, provide flowers for bees, and even as wind-resistant ornamental hedges.
But, its seed easily are spread via the animals and birds that eat its silvery olive-looking fruit, as well as by flowing water and dam it, beaver activity. The tree has silver leaves and black bark, and when in bloom, small yellow, fragrant flowers.
Easy to spread, quick to grow, and able to dominate a landscape, the Russian olive is now classified as a highly invasive species in Canada and the US.
The Might Mite
Begun over 10 years ago, researchers from Centre for Agriculture and Bioscience International (CABI) in Switzerland, the Biotechnology Biocontrol Agency (BBCA), Italy, the University of Belgrade, Serbia, and Ferdowsi University, Mashhad, Iran, have pooled their talents to examine the appetites of a mite and a moth.
Aceria angustifoliae, and the shoot-and-fruit-boring moth Anarsia eleagnella were examined of the 72 insects and mites found within the Russian olive’s natural habitats.
The research scientists chief concern was to ensure that neither moth nor mite would cause eco-damage if/when introduced into another environment, and to monitor their appetite for the Russian olive weed. They monitored the damage caused by the moth and mite on the weed to quantify the damage caused to either kill the weed or at least stymie its rate of growth.
Field tests in Switzerland showed that the Aceria angustifoliae mite targeted a very limited range of plants, preferring the Russian olive.
In 2019, CABI teamed up with Dr. Rosemarie De-Clerck-Floate with the Agriculture and Agri-Food Canada (AAFC) and Dr. Tim Collier of the University of Wyoming to get permission from their respective counties to release the mites in affected areas in North America.
The CFIA (Canada Food Inspection Agency) has, under the authority of the Canadian Plant Protection Act, now approved the mite’s release in Canada.
British Columbia and Alberta, two particularly hard-hit provinces by the invasive weed, are expected to see the first deployment of the mites.
Dr. Phillip Weyl, a research scient with CABI’s Weed Biological Control said, “Permission to release Aceria angustifoliae in Canada is a major step forward to having a viable biological control to tackle Russian olive in Canada and, perhaps in time, other parts of North America.”
Added Dr. De Clerck-Floate: “We are now eager to trial releases of the gall mite at sites in British Columbia and Alberta where Russian olive is particularly invasive in sensitive riparian habits. Based on CABI’s thorough test results, we have confidence in the agent’s potential as a safe and effective agent in curtailing Russian olive’s aggressive spread.”