Traits and control of invasive mile-a-minute (Persicaria perfoliata) in western New York

Abstract

Invasive and nuisance species are recognized as a major threat to natural ecosystems and a leading threat to biodiversity. Mile-a-minute, Persicaria perfoliata, is an invasive species in North America and is native to Asia and the Philippines. It was introduced in the United States in the late 1800s and has become a serious invasive species in the eastern United States. Herbicides, biological control, and mechanical control methods have been effective for controlling mile-a-minute, but their relative efficacy is not known. I evaluated herbicide, mechanical and combined treatments for mile-a-minute over three years at two sites. All methods were effective at reducing mile-a-minute percent cover. Treatment type affected mile-a-minute percent cover in the first year of my study, when the mechanical-only treatment was less effective than herbicide treatments at the first resample. However, there were no significant differences among treatments in the second or third year of the project. My results indicate that mechanical, herbicide, or combined treatments can effectively manage mile-a-minute. However, because germination continues through October revisits are needed after initial treatment applications regardless of methods chosen. I also found that there was inter-year variability in the phenology of mile-a-minute and was an important indicator that control methods need to be applied before flowering occurs. To further evaluate how phenology and plant phenotypes vary among mile-a-minute populations, I conducted a greenhouse experiment. I grew mile-a-minute plants from seeds of regional and local populations under varying environmental conditions. I observed that mile-a-minute grew faster, larger, and was phenologically 2 advanced under warmer, wetter, and sunnier conditions. However, mile-a-minute survival and growth was still high under low resource conditions, and plants in low resource conditions began to reproduce by the eighth week of the experiment. Seed source was a significant predictor of growth and plant traits, indicating genetic differences among populations and among seed collection times. Surprisingly, differences among seed sources from the same populations collected at different times were similar to differences among populations. Mile-a-minute is primed to continue invading many habitats given its phenotypic plasticity and trait diversity produced by sexual reproduction. Although typically found in sunny, high light edge environments, mile-a-minute grows well in many environmental conditions, which means it can continue to spread to new environments. Since mile-a-minute can survive in low resource environments, land managers must survey deep into forests near infestations for plants as they may potentially seed.