Comparison of Four Techniques to Control Elephant Ear

Elephant ear (Colocasia esculenta [L.] Schott), introduced to the San Marcos River (Hays County, Texas) in the 1900s, now forms dense stands and dominates many areas previously inhabited by native vegetation. Texas Parks and Wildlife Department lists the plant as an exotic species needing management consideration. Four potential vegetative control techniques (manual removal, application of glyphosate herbicide, mechanical cutting, and a combination of mechanical cutting followed by application of glyphosate to cut petiole) were applied to elephant ear growing in the San Marcos River at five-week intervals for one year. Effectiveness of each technique was evaluated based on three criteria: extent of decrease in elephant ear leaf cover, number of treatment applications required to achieve control, and time required to apply technique. Manual removal effectively achieved control with the fewest applications and resulted in the lowest overall elephant ear leaf cover. It also required the least application time. Herbicide application also effectively controlled elephant ear, although the technique required a longer application time and a greater number of applications. Neither mechanical cutting nor combined mechanical cutting/herbicide application resulted in control. Based on the three criteria, both manual removal and herbicide application are effective in controlling elephant ear.