Biology of invasive plants 4. Arundo donax L

Authors: Goolsby, John; Moran, Patrick; MARTINEZ JIMENEZ, MARICELA - Instituto Mexicano De Tecnologia Del Aguas; Yang, Chenghai; CANAVAN, KIM - Rhodes University; PAYNTER, QUENTIN - Landcare Research; OTA, NOBORU - Csiro, Black Mountain Laboratories; KRITICOS, DARREN - Commonwealth Scientific And Industrial Research Organisation (CSIRO)

Submitted to: Invasive Plant Science and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2023
Publication Date: 7/17/2023
Citation: Goolsby, J., Moran, P.J., Martinez Jimenez, M., Yang, C., Canavan, K., Paynter, Q., Ota, N., Kriticos, D. 2023. Biology of invasive plants 4. Arundo donax L. Invasive Plant Science and Management. 16(2):81-109. https://doi.org/10.1017/inp.2023.17.
DOI: https://doi.org/10.1017/inp.2023.17

Interpretive Summary: Arundo donax, also known as giant reed, or carrizo cane is a large (up to 25 ft tall) perennial grass from Mediterranean Europe, northern Africa, the Middle East and India that was introduced to North America by Spanish colonists hundreds of years ago for use in roofing and fences. However, giant reed has become a damaging invader in the southern U.S., especially in the Rio Grande Basin of Texas and Mexico, as well as in California. Giant reed forms dense thickets along rivers, canals and reservoirs, removing water that is needed for agriculture in regions where rainfall is scarce, and giant reed also promotes wildfires, displaces native plants and animals, hinders access and visibility for law enforcement and facilitates the invasion of cattle fever ticks along the international border with Mexico. This paper reviews the distribution, biology and impacts of this invasive weed in North America with emphasis on the Rio Grande Basin, California and Central Mexico. Methods for management of this invasive weed include a discussion of the integration of mechanical and biological control strategies.

Technical Abstract: Arundo donax, also known as arundo, giant reed, or carrizo cane is a large (up to 10m tall) perennial grass from Mediterranean Europe, northern Africa, the Middle East and India that was introduced to North America by Spanish colonists hundreds of years ago for use in roofing and fences. However, giant reed has become a damaging invader in the Rio Grande Basin of Texas and Mexico and in California in the U.S, as well as in parts of South America, South Africa, Australia, and New Zealand. Giant reed forms dense thickets along rivers, canals and reservoirs, removing water that is needed for agriculture in regions where rainfall is scarce, and giant reed also promotes wildfires, displaces native plants and animals, hinders access and visibility for law enforcement and facilitates the invasion of cattle fever ticks along the international border of the U.S. with Mexico. This paper reviews the distribution, biology and impacts of this invasive weed in North America with emphasis on North America-the Rio Grande Basin, California and Central Mexico. Climate modeling successfully predicted global introduced range of A. donax and specifically its North American invasive range, based on native range climate attributes from Mediterranean Europe. Arundo donax could potentially expand its range in many parts of Africa and South America. Spain is the source of invasive populations in North America. Analysis of satellite images made in 2002 indicated that A. donax covered 6,360 ha along 600 river-km of the Rio Grande between the mouth of the river at Brownsville to El Paso, TX, with 4,775 ha along tributary rivers in Mexico, for a total 11,135 ha or 27,515 acres infested with arundo in the Lower Rio Grande Basin, and many additional unquantified infestations in central Mexico and along rivers in Texas. Arundo invasion increased in this area by 2007, and covered at least 4,100 ha in California by 2020. Arundo donax invasions in North America have been facilitated by human-aided dispersal of plants, and favored by human disturbance of riparian ecosystems, especially the damming of rivers and resulting conveyance flows. Arundo donax benefits from and recovers more quickly than native vegetation from disturbance events, including wildfires and flooding. Arundo donax is highly stress tolerant. Chemical control of giant reed with herbicides, and mechanical control by mowing shoots, can be effective but are costly, reduces plant biodiversity, poses environmental risks in sensitive riparian and aquatic habitats, requires repeated use, and often does not permanently control populations. Mechanical 'topping' of shoots, with a boom sickle bare mower attached to a tractor, can be effective in reducing live biomass and increasing visibility along the Rio Grande. Starting in the early 2000s, the USDA-ARS developed the world's first biological control program targeting an invasive grass, focusing on arundo. Two insects, a shoot tip-galling wasp (Tetramesa romana) and a rhizome- and shoot-feeding armored scale (Rhizaspidiotus donacis) were introduced to the Lower Rio Grande Basin in 2009 and 2011, respectively. Over 1 million arundo wasps were released through a mass-rearing program, and they have dispersed established throughout the Lower Rio Grande Basin. By the sixth year after release, the arundo wasp had reduced live biomass by 32% along the Rio Grande. This reduction translates to a water savings valued at $4.4 million USD per year. The arundo armored scale, now established at many sites in the Lower Rio Grande Basin, does not disperse rapidly, but in release plots, in combination with the arundo wasp, live biomass is reduced by 55%. The arundo wasp and armored scale have been released and are established at some sites in northern California. A third agent, the arundo leafminers, Lasioptera donacis, has been permitted for release in North America a