“ Salvinia molesta . Infestation in the Lower Colorado River.”

“Salvinia molesta. Infestation in the Lower Colorado River.” Presents: Oscar H. Torres U. University of Arizona Department of Soil, Water and Environmental Science. Aquatic Plants Course, SWES 525.

Antecedents. • Mitchell (Giant salvinia). • Brazilian native, free floating aquatic fern. • Reproduces by vegetative fragmentation.

History • 1999 USFWS discovered S. molesta within the Cibola National Wildlife Refuge. • Other reports as South as Yuma, AZ. • Origin: Irrigation outfall drain (Palo Verde Irrigation District, [PVID]).

Adverse effects • Blocks water system’s intakes and outlets. • Ecology & Economy: Limiting free water space (Recreation). Usurping in situ vegetation. Increasing anoxic conditions (Fishery).

Infested Sites

Lower Colorado River Giant Salvinia Task Force • Bureau of Reclamation. • Bureau of Land Management. • Fish and Wildlife Service. • Department of Agriculture. • PVID. • Other local, State, and Mexican Agencies.

Objective • Eradicating or controlling S. molesta along PVID and Lower Colorado River (LCR). Integral Action Plan Physical control. Chemical spray applications. Biological control. Public information.

Physical Removal (PR). • -Nets. • -Excavation. • -Booms. • -Skimmer.

PR • Advantages: • Non polluting. • Disadvantages: • Expensive and effort consuming. • Complete removal was not usually achieved (native flora).

Chemical applications (CA). • Chelated Copper 10% to 15% Solution. (Clearigate, Komeem). • Diquat-Glyphosate Mixture 15% diquat-5% glyphosate Solution, and Surfactant. • Diquat alone.

CA. • Fluridone. • Diquat dibromide and Surfactant. • Glyphosate and Surfactant.

CA • Advantages • Effective on eradicating plants.

CA (Disadvantages) • Could copper levels. • Glyphosate and diquat have { } use in waters with sediments. • Copper based, { } where fauna resides, & where =CO3> 50 ppm. • Non substrate specific. • Polluting. • Expensive & Effort consuming.

Biological Control (BC). • Cyrtobagous salviniae weevils. • 2001 USDA approved tests on biocontrol. • 2003 USDA approved release at LCR.

BC. • From 2003 to 2005 weevils controlled salvinia population where applied. • Weevils need + time. • + investigation to conclude if weevils are successful in long spans.

BC • Advantages • Species specific. • + Effective in stagnant waters. • Inexpensive.

BC • Disadvantages • - Ineffective during winter (~5° C). • - Ineffective on waters.

Public Education and Outreach

Throughout 2006 • August: Biocontrol monitoring continues along LCR: 3000 weevils/m2. • October: Diquat & glyphosate application: @ Estes & Browns drain (salvinia present). • Spraying as salvinia disappeared.

Conclusions & propositions • The integrated approach solution has reached the results.

Conclusions & propositions • BC: research on larvae. 3 years of continual evaluation. • Reclamation procedures: successful in stagnant waters

Conclusions and proposals • Perhaps curbed salvinia: natural conditions limited nutrients turbulence temperature • Removal of 90-95% @ PVID. • Removal on river: total (natural conditions?)

“ Salvinia molesta . Infestation in the Lower Colorado River.”