Date of Completion


Document Type

Honors College Thesis


Rubenstein School of Environment and Natural Resources

Thesis Type

Honors College

First Advisor

Eric Roy

Second Advisor

Gillian Galford

Third Advisor

Aaron Mrotek


Invasive species, glyphosate, Aravaipa Canyon, Vinca major, environmental conditions


Invasive species are one of the top global threats to biodiversity, and guidelines for context-dependent local management of invasive species is needed. Vinca major is a vine native to Eurasia that acts as an invasive in the Southwestern United States, including Aravaipa Canyon, an ecologically important corridor with a rare perennial stream in the Sonoran Desert. Eradication efforts for V. major in the canyon focus on glyphosate (Roundup) application. However, detailed guidance on the ideal environmental conditions under which to apply glyphosate to achieve maximum V. major die-off would be useful to land managers and is a current knowledge gap. To address this gap, a treatment experiment was conducted in the field. Plots of mature V. major were sprayed with glyphosate at regular intervals throughout the spring of 2022, capturing seasonal changes environmental conditions including temperature, humidity, daylight, and precipitation across the winter-summer gradient. Glyphosate had a substantial impact on V. major die-off, with early spring being the most effective time of application and late spring being less effective. Application date was a strong predictor of die-off and no single environmental factor was a better predictor of glyphosate efficacy. Date of application likely captures a combination of the many environmental factors that change over the course of the spring, such as temperature, humidity, soil moisture, and length of daylight. Based on these results, I recommend that spring glyphosate application on V. major be carried out no later than Julian date 100, or April 9 th -10th .

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.