Invasive Species: Plants

Buffelgrass (Cenchrus ciliaris) was introduced as a forage grass into the southwestern U.S. from Africa. The species has since spread into the Sonoran Desert where it presents a fire hazard for Saguaro cactus (Carnegiea gigantea), palo verde (Parkinsonia microphylla), and other plants native to the desert ecosystem.

Further information on this highly invasive grass species and its management can be found at:

• Southern Arizona Buffelgrass Coordinating Center
• A Buffelgrass Aerial Spraying Pilot Project: Spray Application and Deposition
• Aerial Spot-Sprayer Demonstration

Garlic mustard (Alliaria petiolata) is one of the most pernicious invasive species in the U.S. It can readily displace desirable native species through competition for available light, nutrients, and moisture. While known in riparian and moist deciduous forests of Canada and 30 States in the U.S., it is also found under many coniferous species in Canada and has been progressively moving into drier habitats as it migrates westward along railroads, disturbed soils, and riparian areas.

This species has not yet been found in Region 3 but may eventually reach suitable habitat in the Region at some point in the future (see distribution map in USDA PLANTS Database). Any infestations in AZ or NM should be eradicated as soon as possible and reported to the Regional invasive species coordinator at 505-842-3280. Further information on garlic mustard and its management can be found at:

• Garlic mustard - Northeastern Area
• Garlic mustard (Alliaria petiolata) - Minnesota Department of Natural Resources

Due to the release of four species of saltcedar leaf beetle (Diorhabda spp.) in the Southwest as biological control agents for invasive saltcedar (Tamarix spp.), it may no longer be necessary to treat saltcedar in a particular watershed once the saltcedar is controlled by these beetles through repeated defoliations.

However, areas with defoliated saltcedar may become infested by other invasive plants or common weeds that could require treatment. In addition, expansion of these beetle species threatens saltcedar nesting habitat now used by the endangered southwestern willow flycatcher (Empidonax traillii extimus) in lieu of its former nesting habitat of native willow.

Restoration projects that can replace saltcedar with native willow species may be necessary in areas used for nesting by the flycatcher. Further information on saltcedar leaf beetle species and their distribution may be found at the Tamarisk Coalition’s website.