Integration of mechanical topping methods to accelerate biological control of Arundo donax

Authors: Goolsby, John; RACELIS, ALEX - University Of Texas Rio Grande Valley; Moran, Patrick; KIRK, ALAN - European Biological Control Laboratory (EBCL); KASHEFI, JAVID - European Biological Control Laboratory (EBCL); Smith, Lincoln; BON, MARIE-CLAUDE - European Biological Control Laboratory (EBCL); LACEWELL, RON - Texas A&M Agrilife; VACEK, ANN - University Of Texas Rio Grande Valley; MARTINEZ-JIMENEZ, MARICELA - Instituto Mexicano De Tecnologia Del Aguas; Perez De Leon, Adalberto - Beto

Submitted to: International Symposium on Biological Control of Weeds
Publication Type: Proceedings
Publication Acceptance Date: 8/21/2018
Publication Date: 1/15/2019
Citation: Goolsby, J., Racelis, A., Moran, P.J., Kirk, A., Kashefi, J., Smith, L., Bon, M., Lacewell, R., Vacek, A., Martinez-Jimenez, M., Perez De Leon, A.A. 2019. Integration of mechanical topping methods to accelerate biological control of Arundo donax. International Symposium on Biological Control of Weeds. p. 290.

Interpretive Summary: Arundo donax L., known as giant reed or carrizo cane, is a weed native to Spain and invasive in the Rio Grande Basin, especially along the Rio Grande between Del Rio and Brownsville, TX. Arundo donax has historically dominated riverine habitats along the Rio Grande where it uses scarce water resources, lowers riverine plant biodiversity, reduces visibility for law enforcement, and facilitates the invasion of cattle fever ticks from Mexico. Two biological control insects from Spain, arundo wasp Tetramesa romana Walker and the arundo scale, Rhizaspidiotus donacis (Leonardi), were released in 2019 and 2012, and having significant impacts on this weed along the Rio Grande in Texas and Mexico. To further accelerate the decline of A. donax, we developed methods to integrate biological and mechanical controls. Mechanical topping (cutting) of A. donax at 3 feet improves immediate visibility of the international border for law enforcement personnel and also accelerates the decline of this invasive weed. Topping increases the production of A. donax side shoots that are preferred egg-laying sites for the arundo wasp. Increased egg-laying or attack by the arundo wasp on side shoots leads to long-term stunting of the A. donax. To test the effectiveness of integrating biological and mechanical methods on A. donax, a study was conducted from January 2017 to May 2018, at the U.S. Fish and Wildlife, Lower Rio Grande Valley National Wildlife Refuge along the Rio Grande near Hidalgo, TX. We found that topping increased visibility through the A. donax stands to greater than 25 feet, increased solar penetration at ground level, which ultimately led to a significant increase in the diversity and abundance of desirable native plant species as compared to un-topped plots. Integration of mechanical and biological control methods accelerated the decline of A. donax, improves visibility along the international border, and ultimately led to restoration of desirable plant species at this site on the Rio Grande. Methods for large-scale implementation of the integrated approach using specialized tractors with 50 feet long movable arms and attached hedgers, have been developed by ARS and transferred to the U.S. Border Patrol for implementation on the Rio Grande for A. donax weed management.

Technical Abstract: Arundo donax L., known as giant reed or carrizo cane, is native to Mediterranean Europe and invasive along the Rio Grande especially between Del Rio and Brownsville, TX. Arundo donax has historically dominated riparian habitats along the Rio Grande where it competes for scarce water resources, lowers plant biodiversity, reduces visibility for law enforcement, and facilitates the invasion of cattle fever ticks from Mexico. Two biological control agents from Spain, the arundo wasp Tetramesa romana Walker and the arundo scale, Rhizaspidiotus donacis (Leonardi), are widely established along the Rio Grande and are having significant impacts against A. donax in Texas and Mexico. To further accelerate the decline of A. donax, we have integrated biological and mechanical methods. Mechanical topping (cutting) of A. donax at 1 m improves within stand visibility for law enforcement, which leads to return of native vegetation and the decline of this invasive weed. Topping increases the production of A. donax side shoots that are preferred oviposition sites for the arundo wasp. Increased ovipositon by the arundo wasp on side shoots causes extensive gall formation and leads to long-term reduction in growth of A. donax. To test the impacts of integrating biological and mechanical methods on A. donax, a study was conducted from January 2017 to May 2018, at the U.S. Fish and Wildlife, Lower Rio Grande Valley National Wildlife Refuge along the Rio Grande near Hidalgo, TX. We found that topping of A. donax immediately increased within stand visibility, increased solar penetration at ground level, and significantly increased the diversity and abundance of native plant species as compared to un-topped control plots. Integration of mechanical and biological control methods was shown to accelerate the decline of A. donax, which improved visibility of the international border and ultimately led to restoration of the desirable native riparian plant community at this field site on the Rio Grande. Methods for large-scale implementation of this integrated approach using specialized tractors with 50 ft movable arms and attached hedgers have been developed by ARS transferred to the U.S. Border Patrol for use on the Rio Grande for A. donax weed management.