Weed biocontrol in landscape restoration

Authors: Lake, Ellen; HOUGH-GOLDSTEIN, JUDITH - University Of Delaware

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 12/2/2015
Publication Date: 7/1/2016
Citation: Lake, E.C. and Hough-Goldstein, J. Weed biocontrol in landscape restoration, p. 4. In Gover, A.E. (Ed.) Proceedings of the First Annual Meeting of the Northeastern Plant, Pest, and Soils Conference. January 3-7, 2016. Philadelphia, PA. 2016. (Proceedings)

Interpretive Summary: Natural area managers often implement weed biological control programs with the goal of restoring native plant communities and/or ecosystem services to a pre-invasion level. These objectives may be achieved in some areas with biological control alone; however, in other sites integration of biological control with additional management techniques is necessary. Biological control has been successfully integrated with herbicides, mechanical control, fire, and grazing to manage invasive weeds. The choice of which control technique(s) to implement in a given system may depend on several factors including restoration goals, treatment costs, the specific habitats invaded by the weed, and the type of damage caused by the biological control agent. Mile-a-minute weed, Persicaria perfoliata (L.) H. Gross, is an aggressive annual vine that has invaded the eastern United States. In some cases, successful biological control of mile-a-minute weed by the weevil Rhinoncomimus latipes Korotyaev has resulted in replacement by other undesirable vegetation, the invasive treadmill effect. Two small-scale experiments in this system successfully integrated biological control with native plantings to restore plant communities. In one experiment, weevil releases were integrated with a single application of a pre-emergent herbicide and plantings of a native forb and tree. Two years later, the cover of native plants in the integrated treatment plots was greater than 80%. In a second experiment, biological control was combined with plantings of a native seed mix. The richness and diversity of native plants increased after three years in the integrated plots. In both experiments, the integration of techniques reduced the abundance of the target weed, promoted recruitment of additional native plant species that were not included in the plantings, and prevented dominance by other invasive plants compared to non-planted control plots.

Technical Abstract: Weed biological control programs in natural areas are often undertaken with the goal of restoring native plant communities and/or ecosystem services to a pre-invasion level. These objectives may be achieved in some areas with biological control alone; however, in other sites integration of biological control with additional management techniques is necessary. Biological control has been successfully integrated with herbicides, mechanical control, fire, and grazing to manage invasive weeds. The control technique(s) implemented in a given system may depend on restoration goals, treatment costs, the specific habitats invaded by the weed, and the type of damage caused by the biological control agent. Mile-a-minute weed, Persicaria perfoliata (L.) H. Gross, is an aggressive annual vine that has invaded the eastern United States. In some cases, successful biological control of mile-a-minute weed by the weevil Rhinoncomimus latipes Korotyaev has resulted in replacement by other undesirable vegetation, the invasive treadmill effect. Two small-scale experiments in this system successfully integrated biological control with native plantings to restore plant communities. In one experiment, weevil releases were integrated with a single application of a pre-emergent herbicide and plantings of a native forb and tree. Two years later, the cover of native plants in the integrated treatment plots was greater than 80%. In a second experiment, the combination of biological control and plantings of a native seed mix resulted in increased richness and diversity of native plants after three years. In both experiments, the integration of techniques reduced the abundance of the target weed, promoted recruitment of additional native plant species that were not included in the plantings, and prevented dominance by other invasive plants compared to non-planted control plots.