Biological Control of Arundo donax

Authors: Goolsby, John; Moran, Patrick; KIRK, ALAN - European Biological Control Laboratory (EBCL); KASHEFI, JAVID - European Biological Control Laboratory (EBCL); BON, MARIE CLAUDE - European Biological Control Laboratory (EBCL); CRISTOFARO, MASSIMO - Bbca-Onlus, Italy; MARTINEZ-JIMENEZ, MARICELA - Instituto Mexicano De Tecnologia Del Aguas; RACELIS, ALEXIS - University Of Texas Rio Grande Valley; RUBIO, AMEDE - Texas A&M International Unviersity; VAUGHN, THOMAS - Texas A&M International Unviersity; REILLY, FRANK - Logistics Management Institute Lmi

Submitted to: International Symposium on Biological Control of Weeds
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2023
Publication Date: N/A
Citation: N/A

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, a.k.a. giant reed, or carrizo cane is a large 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. 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, 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. USDA-ARS developed the world's first biological control program targeting an invasive grass, focusing on A. donax. 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 leafminer Lasioptera donacis, was released in Texas in 2016, but did not establish. Further releases are planned in California where climatic conditions may be more favorable. Methods for successful management of this invasive weed include the integration of mechanical and biological control strategies, for example, topping at 1m followed by attack by arundo wasps on subsequent abundant lateral shoots. Mechanical topping with a tractor mounted sidebar mower, is effective in reducing live biomass. Over 700 km of the Rio Grande have been topped over multiple years accelerating declines in biomass. Biological control integrated with mechanical topping is likely to be the most critical tool used to reduce the economic and environmental damage caused by A. donax.