Comment from James Manhart

I am an associate professor in the Department of Biology at Texas A&M University. I have worked on several projects involving rare and endangered plant species in the Rio Grande Basin (RGB). In addition, I am currently working on a genetic analysis of Arundo donax with the goal of determining its origin(s), particularly in the RGB. I have been doing field work in this part of Texas for over 20 years and I have been astounded by the increase in size of the Arundo donax stands in this area during that time. They clearly are a threat to native plant species due to their rapid growth. In addition, we have never observed any animals either eating Arundo or living in the stands. It essentially creates a dead zone where little else survives. It also creates a significant fire hazard, with intense fires destroying the remaining native plants with little or no effect on Arundo. Due to the size of the infestations and the difficulty in getting to the infestations in many areas, the only method that shows any promise to control Arundo in the RGB is the use of biocontrol agents. The combination of the Arundo wasp (already released) and the scale should stress the plants to the point that it will slow down their spread and allow native plants to recolonize areas of infestation.