ARS | Publication request: Japanese Raspberry (Rubus parvifolius L.): An Invasive Species Threat in Savanna and Prairie

Submitted to: North American Prairie Conference
Publication Type: Proceedings
Publication Acceptance Date: April 7, 2011
Publication Date: March 20, 2012
Citation: Drobney, P.M., Widrlechner, M.P. 2012. Japanese Raspberry (Rubus parvifolius L.): An Invasive Species Threat in Savanna and Prairie. In: Williams, D., Butler, B., Smith, D., editors. Proceedings of the 22nd North American Prairie Conference, University of Northern Iowa, Cedar Falls, Iowa. p. 148-152.

Interpretive Summary: Non-native woody plants can escape from cultivation and potentially become invasive, disrupting both native plant communities and farming systems. It is crucial to identify new invaders before they spread widely. Sharing information about potential invasions alerts land managers to new problems while they are still manageable. Japanese raspberry is native to eastern Asia and Australia and has now naturalized in several locations in Illinois, Iowa, Massachusetts, Missouri, and Ohio. This species was introduced in North America for food and erosion control, but the authors are concerned that it is becoming a serious invasive threat in savannas and prairies. It was found in a former commercial game hunting farm on Walnut Creek National Wildlife Refuge (NWR) (now Neal Smith NWR) in 1991, and was identified as Japanese raspberry in 1995. It thrives in shade in a remnant savanna on the refuge, forming rapidly expanding near-monoculture populations. Efforts to control it with herbicide treatment since its discovery have been unsuccessful, but also somewhat sporadic. A second population within a mile of the refuge in a roadside has thrived in full sun. County dredging of ditches for drainage improvement may be serving as a vector for its expansion. Japanese raspberry grows vigorously and spreads via rooting from low-arching to prostrate canes that are up to 10 feet long, and its seeds can be dispersed by birds. First-year canes are green to purplish-green in summer, though they turn reddish brown in winter. It has small pink flowers and bright red fruits. This information should be useful for ecologists, land managers and horticulturists in making wise planting choices and for initiating control efforts.

Technical Abstract: Japanese raspberry, (Rubus parvifolius L.) is native to eastern Asia and Australia and has naturalized in several locations in Illinois, Iowa, Massachusetts, Missouri, and Ohio. This species was introduced in North America for food and erosion control, but the authors are concerned that it is becoming a serious invasive species threat in savannas and prairies. It was found in a former commercial game hunting farm on Walnut Creek National Wildlife Refuge (NWR), (now Neal Smith NWR) in 1991, and was identified as Japanese raspberry in 1995. It thrives in shade in a remnant savanna on the refuge forming rapidly expanding near-monoculture populations. Efforts to control it with herbicide treatment since its discovery have been unsuccessful, but also somewhat sporadic. A second population within a mile of the refuge in a roadside demonstrates its ability to thrive in full sun. County dredging of ditches for drainage improvement may be serving as a vector for its expansion. Japanese raspberry grows vigorously and spreads via rooting from low-arching to prostrate canes that are up to 300 cm long, and its seeds can be dispersed by birds. In summer, primocanes are green to purplish-green, though they turn reddish brown in winter. It has small pink flowers and bright red fruits.