Emily Malkin, Soil Conservationist
Many have heard the term “invasive species”, but what exactly defines one? Simply put, an invasive species is any organism that can cause ecological harm to its environment/any environment where it is not considered native. Invasive plant species are a danger to native plants as they can out-compete or kill off the native species, as well as add or take nutrients from the soil that can cause damage. One invasive that is especially heinous to grasslands and forests in Clinton County is a shrub called Autumn Olive.
Originally introduced to the US in the 1830’s from Asia, Autumn Olive was commonly planted as food and habitat for wildlife. It was also thought to have been beneficial as windbreaks along with increasing soil stabilization. But, after some time, its invasive qualities were recognized. It grows quickly and spreads just as fast while being shade and sunlight tolerant. Because of this, it can be particularly hard to control and eradicate. The fast growth of this species means that it can easily out-compete any native species that are trying
to grow under, around, or near it. One of the biggest concerns with Autumn Olive is its ability to fix a large amount of nitrogen in the soil. Most of our local grasslands and prairies are accustomed to low-nutrient growing conditions, so the excess nitrogen hinders their development.
One upside to this invasive
species is that it is fairly easy to recognize. Its oval leaves grow in an alternating pattern on the stems that come to pointed tips. The leaves are also a bright green on the tops and have a distinctive silvery shine to the undersides. The stems and twigs also have a silver sheen, but often have a brown speckled appearance. The tubular flowers produced are cream or light yellow with a fragrant smell during spring bloom, but tend to bloom between August and September in Michigan. Following the flower bloom and until the end of October, red berries that are lightly speckled can be observed and are a favorite snack of many birds.
However, controlling Autumn Olive can seem particularly tricky. Simply mowing or cutting it back can prove beneficial to the plant, as it serves to prune it and stimulate growth. In addition, the roots continue to spread and encourage re-growth. If manual removal is your choice of eradication, completely pulling the shrub, including its roots, will do the trick. Also, cutting the shrub and applying herbicide to the stump will work as well. Other control practices include herbicide application, foliar sprays, and prescribed burning in fire-adapted communities. When disposing of the shrub after control measures, ensure that the roots will dry out completely. If there is fruit present, plants should be burned or bagged and placed in landfill. Although landscape waste cannot generally be disposed of in landfills, Michigan law permits the disposal of invasive species plant parts.
NRCS recognizes the need to control the spread of this species and offers programs such as Brush Management and Herbaceous Weed Control that can help with the eradication planning as well as some of the costs. If you would like more information on Autumn Olive, control measures, our cost share programs, or any other Michigan invasive species, please contact the St. Johns Field Office at 989-224-3720.
References
“Autumn Olive.” Michigan.gov, Michigan Department of Natural Resources Michigan-Natural Features Inventory, Feb. 2012, www.michigan.gov/documents/dnr/Autumn_Olive_389111_7.pdf.
“Autumn Olive.” Invasive Species - Autumn Olive, Michigan Invasive Species, 2021, www.michigan.gov/invasives/0,5664,7-324-68002_74282-368763--,00.html.
Rowse, Linnea. “Invasive Species Focus: Autumn Olive.” Michigan Audubon, 18 Aug. 2020, www.michiganaudubon.org/invasive-species-focus-autumn-olive/.