A Management Guide for Invasive Plants of Southern Forests

Miller, James H.; Manning, Steven T.; Enloe, Stephen F. 2010. A management guide for invasive plants in southern forests. Gen. Tech. Rep. SRS–131. Asheville, NC: U.S. Department of Agriculture Forest Service, Southern Research Station. 120 p.

Invasions of nonnative plants into forests of the Southern United States continue to spread and include new species, increasingly eroding forest productivity, hindering forest use and management activities, and degrading diversity and wildlife habitat. This book provides the latest information on how to organize and enact prevention programs, build strategies, implement integrated procedures for management, and proceed towards site rehabilitation and restoration. Effective control prescriptions are provided for 56 nonnative plants and groups currently invading the forests of the 13 Southern States. A companion book, “A Field Guide for the Identification of Invasive Plants in Southern Forests,” (Miller and others 2010 (slight revision 2012 and 2013)) includes information and images for accurate identification of these invasive plants.

Keywords: Invasive plant control methods, alien plants, exotic weeds, forest noxious plants, invasive exotic plants, invasive non-indigenous plants, forest herbicide application methods, regional and state strategies for invasive plant management.

Acknowledgments

Introduction

General Principles for Managing Nonnative Invasive Plants

Regional and State Program Elements for Invasive Plant Management

Strategies for Confronting a Spreading Invader

A Shift in Mindset Must Occur Followed by Actions

Principles to Follow

Considerations in Developing a Site-Specific Plan

Elements and Tasks of an Invasive Plant Management Program

Effective Treatments for Integrated Management of Nonnative Invasive Plants

Herbicide Application Methods

Selecting an Effective Herbicide

Adjuvants and Additives to Herbicide Spray Solutions

Mixing Herbicides

Backpack Sprayers

Selective Herbicide Applications

Broadcast Herbicide Applications

Manual Methods

Mechanical Methods

Cultural Methods

Water-Level Manipulation

Biological Control Methods

Prescribed Grazing

Mulching and Solarization

Rehabilitation, Restoration, and Reclamation

Herbicide Use in Restoration of Native Grasses

Management Strategies and Herbicide Prescriptions for Invasive Plants

Invasive Trees

Invasive tree species hinder reforestation and management of rights-of-way and natural areas as well as dramatically alter habitats. Some species occur initially as scattered trees and eventually form dense stands if not controlled. Most spread by prolific seed production and abundant root sprouts. Depending on conditions, they can be eliminated with herbicides by stem injection, cut-treat, soil spots, basal sprays, and foliar sprays. Following stem control, total elimination requires surveillance and treatment of root sprouts and plant germinants that originate from the soil seed bank.

Invasive Shrubs

Invasive shrubs often occur with invasive tree species and present similar problems. Herbicide control options are similar to those for trees, with the exception that foliar sprays can be used more often. All are shade tolerant with bird-dispersed seeds, resulting in scattered plants under existing forest canopies, which require additional surveillance within the interior of forest stands.

Invasive Vines

Invasive vines are some of the most troublesome invaders because they often form the densest infestations, making herbicide applications and other treatments difficult. Many of these vines overtop even mature forests and often form mixed-species infestations with invasive trees and shrubs. Specific herbicides can be effective on certain vines while not controlling but actually releasing any underlying nonnative trees and shrubs. In these situations, select the best herbicide or herbicide mixture for controlling all the invasive species in a mixed-species infestation. Vine control is always difficult because foliar-active herbicides must move through lengthy vines to kill large woody roots and root crowns. Thus, herbicides that have both soil and foliar activity are often the most effective. Only the lower foliage within sprayer reach needs to be treated with a herbicide having both foliar and soil activity. With all herbicides, spray foliage of climbing stems as high as possible and if not controlled, then cut vines. Treat cut stems or allow sprouting before foliar retreatment. When cutting treatments are used, cut as low as possible and also remove the upper portion high enough to prevent regrowth reaching the upper vine to act like a trellis.

Invasive Grasses and Canes

Nonnative grasses and bamboos continue to spread along highway rights-of-way and, thus, gain access to adjoining lands. Most nonnative invasive grasses are highly flammable; increase fire intensities, subjecting firefighters to higher risk; and spread rapidly after wildfire or prescribed burns. Invasive grasses have become one of the most insidious problems in the field of wildlife management on pasture and prairie lands because they have low wildlife value and leave little room for native plants. Repeated applications of herbicides are required for control with establishment of native plants. Long established bamboo infestation continue to expand without control treatments.

Invasive Ferns

Japanese climbing fern [Lygodium japonicum (Thunb.) Sw.] is presently the only widespread nonnative invasive fern in the temperate parts of the South. Old world or small-leaf climbing fern [L. microphyllum (Cav.) R. Br.] is a severe invasive in south to central Florida.

Japanese Climbing Fern

Invasive Forbs

Forbs are broadleaf herbaceous plants that usually reproduce by seed and can be perennial with flattened stems on the ground and root crowns that persist over winter. Control treatments are usually by foliar sprays of herbicides. Persistent seeds in the soil and underground stems and rhizomes make control a lengthy and exacting process for eradication and rehabilitation.

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