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Keywords:

  • biological control;
  • competitive plantings;
  • integrated weed management;
  • pre-emergent herbicide;
  • Rhinoncomimus latipes

Abstract

Efforts to suppress an invasive weed are often undertaken with the goal of facilitating the recovery of a diverse native plant community. In some cases, however, reduction in the abundance of the target weed results in an increase in other exotic weeds. Mile-a-minute weed (Persicaria perfoliata (L.) H. Gross (Polygonaceae)) is an annual vine from Asia that has invaded the eastern United States, where it can form dense monocultures. The host-specific Asian weevil Rhinoncomimus latipes Korotyaev (Coleoptera: Curculionidae) was first released in the United States in 2004 as part of a classical biological control program. At three sites invaded by mile-a-minute weed, biological control was integrated with pre-emergent herbicide use and two densities of native plantings. After 2 years, native plant cover differed significantly and was greater than 80% in the plots with plantings and pre-emergent herbicide but less than 30% in the planting treatments without herbicide. Where mile-a-minute cover decreased at the two sites with the greatest pressure from exotic plants, plots were dominated by another exotic weed, Microstegium vimineum (Trin.) A. Camus, Japanese stiltgrass. The combination of biocontrol, pre-emergent herbicide, and revegetation with native plants suppressed mile-a-minute weed, prevented invasion by Japanese stiltgrass, and increased the abundance of native plants. The selection of the management strategies used to control mile-a-minute weed determined the extent of recovery of the native plant community.