Controlling an Invasive Tree with a Native Fungus: Inoculating Ailanthus altissima (Tree-of-Heaven) with Verticillium nonalfalfae in Highly Disturbed Appalachian Forests of Ohio

Highly disturbed forests are commonplace throughout the eastern United States and their residing composition and structure is reflective of their past land use. Management and restoration efforts are complicated by diverse and abundant nonnative invasive plants, including Ailanthus altissima. Verticillium nonalfalfae has been identified as a potential native mycoherbicide option for Ailanthus. To test the efficacy of Verticillium on Ailanthus we designed a study in highly disturbed forests of southern Ohio. At each of five sites, we monitored symptomology, mortality, and rate of spread of stem-inoculated Verticillium on Ailanthus in four inoculated plots and compared it to a control plot. We also monitored native plants for Verticillium symptomology and community responses to Ailanthus control. Our results suggest that Verticillium is an effective tool for controlling Ailanthus with no observed effect on native flora. Further, Verticillium naturally spreads through stands and mortality is slow enough that other resident nonnative invasive plants do not rapidly increase. Study Implications: Managing problematic invasive plants is a costly and time-consuming endeavor that quickly overwhelms resources. The identification and development of native biocontrols will help to suppress invasive plants, especially when considered in conjunction with other control options. Native biocontrols are pests or diseases that are typically nonlethal residents of the local environment but have significant and detrimental impact on nonnative plants. The native fungus Verticillium nonalfalfae along with several other Verticillium species has been identified to kill the invasive Ailanthus altissima. Verticillium can be applied to a subset of Ailanthus stems, and through time, will spread naturally with minimal impact to native species.

Automated summary

Highly disturbed forests in the eastern United States are reflective of their past land use, and their management and restoration efforts are complicated by nonnative invasive plants. Vertical non-alfalfa has been found to be an effective tool for controlling the invasive Ailanthus altissima, with no observable effects on native flora. The study highlights the importance of native biocontrols in suppressing invasive plants.