Horticulture Graduate Seminar: Biotic and Abiotic Risks to Dirca spp. in Managed Landscapes
Dirca spp. have been praised yet remain elusive in horticultural commerce and designed landscapes. Promoting a new taxon inherently comes with risks. In the case of Dirca, challenges with propagation represent a fundamental risk of insufficient supply. Because asexual propagation is not an option, we rely entirely on sexual propagation. Therefore, I sought to understand if and how temperature and precipitation predict fecundity, a question that has implications beyond horticulture for species narrowly endemic in habitats affected by climate change. In addition, I attempted to test the hypothesis that pollen viability and germination account for low fruit set. Through manual introduction of pollinators to caged Dirca plants, I also evaluated the effects of different insect species on subsequent fruit set. I also examined variation among species and provenances in tolerance of low temperature, an abiotic factor of paramount importance for perennial species. Lastly, I characterized the prevalence of leaf miners and their impact on the visual appeal of foliage. Taken together, the results of these studies lead me to conclude that the barriers historically associated with the incorporation of Dirca into managed landscape can be overcome with intentional pollination regimes and that the other risks—cold tolerance and biotic pests—do not pose serious threats to Dirca establishment in Iowan landscapes.
Time4:25 pm - 5:15 pm
Location118 Horticulture Hall, Iowa State University