Discoveries revolving around false hellebore (Veratrum californicum Durand) have caused a paradigm shift in treatment from eradication to harvest and preservation. Test plots set in place 18 years ago to analyze the effectiveness of eradication treatments (tilling, herbicide, mow, and remow) give us a better idea of how false hellebore communities might respond to disturbances caused by harvest. We focused mainly on the tilling, mow, and remow treatments because of similarities to harvest techniques.We found that mow and remow treatments have little effect on the population of false hellebore in the wild. Tilling treatments were effective in reducing the population dramatically; however some recovery in numbers has taken place. Tilled plots showed a significant decrease in mid seral plant populations, and a significant increase in early seral populations. Tilled treatments were also opened up to intermediately desirable and undesirable plants. Mow and remow treatments reacted similarly to each other, with mow treatments showing decreases in mid seral species and with both treatments showing neither an increase nor a decrease in the other seral stages. Mow and remow plots showed a decrease in desirable plants, but an increase in intermediately desirable plants and no increase in undesirable plants. Greenhouse experiments were unsuccessful due to phenological disruptions caused by removal from the native habitat as well as climate and temperature differences.

Veratrum californicum (common name: corn lily) is a wild plant species that grows in the Intermountain West, its range extending from British Columbia to Mexico. Corn lily is of interest because it has the potential to provide pharmaceutical precursors for use in the treatment of cancer. Pharmaceutical companies are currently running clinical trials of new drugs that use these precursors. As such, a sustainable supply of corn lily is needed if these drugs are ever to enter the market. Unfortunately, wild populations of corn lily will not be able to meet the market demand. Therefore, it is necessary that horticultural guidelines be established so that corn lily can be grown in an agricultural setting. Establishing irrigation criteria is one crucial component in this process, as corn lily grows in naturally wet areas and will most likely require supplemental irrigation in an agricultural setting. In order to determine the appropriate level of irrigation for corn lily, an appropriate range of irrigation levels to test in a field trial must be determined. Plant success as a function of irrigation level can then be measured. In order to determine what irrigation levels should be tested, the OSU Malheur Experiment Station monitored the natural environment of corn lily at a variety of locations over the course of four seasons. Results showed that for the majority of its growing season, corn lily occupies a narrow environmental niche where soil water tension ranges from 0 kPa to 30 kPa. With this information, irrigation levels ranging from 5 kPa to 30 kPa were chosen for irrigation trials. In 2009, corn lily plots were established at Ontario, Oregon and McCall, Idaho. Irrigation trials were run in 2010, 2011, and 2012 at Ontario and McCall. Plots were assigned to five irrigation treatments: 5 kPa (added halfway through the 2010 growing season), 10 kPa, 15 kPa, 20 kPa, and 30 kPa. Collectively, the data indicate that the 5 and 10 kPa treatments are most conducive to corn lily survival and growth. In addition, the observed data are consistent with the hypothesis that soil moisture levels in the first month of growth may be the most important determinant in plant growth and survival. / Graduation date: 2013