A Comparison of Eradication Techniques for a Nonindigenous Emergent Plant Species (Colocasia esculenta)
Atkins, Eric O.
Colocasia esculenta (L.) Schott is a nonindiginous emergent plant species that was introduced to Spring Lake and the upper San Marcos River (Hays County, Texas) ecosystem in the 1900s. This species forms dense stands along the river and has demonstrated the ability to dominate many areas previously inhabited by native vegetation. Texas Parks and Wildlife Department has listed C. esculenta as an exotic species needing management consideration. In this study, four eradication techniques were applied to C. esculenta growing along the banks of Spring Lake and the San Marcos River at five week intervals from November 2004 to November 2005. The four techniques were manual removal, application of the herbicide glyphosate, mechanical cutting with hand shears, and a combination of mechanical cutting followed by application of glyphosate to the cut petiole. Data collected and analyzed included leaf cover of C. esculenta, number of treatment applications required to achieve eradication, amount of time required to apply each eradication technique, and percent cover of other plant species growing in each quadrat. The effectiveness of each eradication technique was based on four criteria: the extent of decrease in C. esculenta leaf cover, the number of treatment applications required to achieve eradication, the amount of time for the application of the technique, and the extent of growth by other plant species. After one year C. esculenta leaf cover following both manual removal and herbicide application was significantly less than the leaf cover of the mechanical cutting technique and the control (F4j2s - 34.704, p = <0.001). Manual removal required significantly fewer treatment applications to eradicate C. esculenta than the mechanical cutting and the combination mechanical cut/herbicide techniques (F4,25 = 16.671, p = <0.001) while the herbicide application required significantly fewer applications than the mechanical cutting technique (F4,25 = 16.671, p = <0.001). Neither the mechanical cutting nor the combination mechanical cut/herbicide technique resulted in eradication of C. esculenta. The manual removal technique required significantly less application time than both the mechanical cutting technique and the combination mechanical cut/herbicide technique (F4,25 = 17.364, p = <0.001). The herbicide application resulted in a significantly greater total percent plant cover, excluding C. esculenta, than the control (F4s 25 = 3.192, p = 0.03). Based on the four criteria manual removal and herbicide application techniques are the only techniques effective in eradicating C. esculenta.
Taro, Introduced organisms, Nonindigenous emergent plant species, Colocasia esculenta, Texas, Hays County
Atkins, E. O. (2006). <i>A comparison of eradication techniques for a nonindigenous emergent plant species (Colocasia esculenta)</i> (Unpublished thesis). Texas State University-San Marcos, San Marcos, Texas.