Verticillium nonalfalfae: A potential biological control of the invasive Ailanthus altissima in Pennsylvania
Open Access
- Author:
- Kasson, Matthew Thomas
- Graduate Program:
- Plant Pathology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- April 24, 2012
- Committee Members:
- Donald Durwood Davis, Dissertation Advisor/Co-Advisor
Frederick Eugene Gildow Jr., Committee Member
David Michael Geiser, Committee Member
Daniel J Royse, Committee Member
Michael Craig Saunders, Committee Member - Keywords:
- Verticillium nonalfalfae
Verticillium wilt
Tree-of-heaven
biological control
Ailanthus
invasive species - Abstract:
- In this dissertation I had three main objectives. The first was to utilize tree ring analysis, historic records to better understand the history, distribution, spatiotemporal spread, and growth patterns of the invasive Ailanthus altissima (tree-of-heaven) as a means of explaining why naturally occurring Verticillium wilt epidemics have only recently developed in PA despite a long history of colonization by Ailanthus. Furthermore these investigations sought to provide answers to fundamental questions regarding the biology of Ailanthus such as maximum age at which seed production occurs and maximum lifespan, both of which ultimately affect the management of the species. Second, I carried out a series of multi-year experiments to better understand two separate aspects of Verticillium wilt of Ailanthus: efficacy of Verticillium nonalfalfae as a biocontrol agent against the target host, and intra-specific resistance that may be present within established populations in the U.S. that ultimately would affect large scale use of this potential bioncotrol. Host range studies sought to clarify and expand preliminary host-range testing, and also test whether V. nonalfalfae isolate VnAa140 was host-adapted. Finally, I sought to investigate the role of the unbiquitous exotic ambrosia beetle, Euwallacea validus, which attacks declining Ailanthus trees throughout the study area. The latter studies sought to assess what role, if any, the mycangial fungi of these beetles had on tree health and disease progression, as well as clarifying phylogentic relationships of their mycangial fungi.