Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Plants, Soils, and Climate

Committee Chair(s)

Corey V. Ransom


Corey V. Ransom


Thomas A. Monaco


R. Douglas Ramsey


Dyer’s woad (Isatis tinctoria L.) is a non-native forb that continues to threaten natural areas throughout Northern Utah and much of the Intermountain West. Once introduced, dyer’s woad can become extremely invasive, decreasing forage quality, and displacing native species. While dyer’s woad is found throughout much of Northern Utah, its range in other states remains limited. If promptly managed, control success in these areas will be much higher and populations may be kept at bay before ecological damage becomes severe.

This project tested the ability of dyer’s woad seedlings to compete with common rangeland grasslands at varied densities as well as within stands of other dyer’s woad plants. The aim was to provide insights to the ability of dyer’s woad to invade grassland systems. Additionally, little is known about the most effective control methods for controlling dyer’s woad in diverse grasslands. Three field trials were established to test the efficacy of various herbicides as well as application timings in controlling dyer’s woad populations up to two years after the initial treatment. The response of surrounding vegetation to herbicide treatments and subsequent removal of dyer’s woad was also assessed. The results of this project will provide land managers with information on the most effective herbicides and herbicide combinations to use for dyer’s woad control, based on the site conditions.