Invasive and Competing Plants
Competing and invasive vegetation in forests can impact both regeneration success and biodiversity. Private forest owners can access Penn State Extension’s resources to learn more about invasive forest species and competing plants, identification, and control tips. Information on Integrated Forest Vegetation Management and herbicide control is also available here.
Invasive Forest Species
Invasive species infestations are among the most significant issues affecting US landscapes. In the forest ecosystem, invasive species can manifest asvarious non-native plants, pathogens, and animals.
Such infestations pose a serious threat to the forest’s biodiversity and ecological integrity. Left untreated, these species can result in the destruction of wildlife habitats, reduced forest productivity, and diminished land value.
Invasive vines are some of the more common invasive forest plants. Grapevines, for instance,grow into the tops of trees and can cause disfigured trees, as well as block light and slow the tree’s food synthesis. Vines such asmile-a-minute andoriental bittersweet can create dense foliage that blankets and gradually suffocates native vegetation.
Other noxious weeds found in Pennsylvania forests include theJapanese barberry woody plant,multiflora rose, and variousprivet shrubs. Tree-of-heaven is anotherrapidly growing invasive tree and noxious weed. The tree’s extensive root system makes it difficult to control, butapplying systematic herbicides at the optimum time can be effective.
Managing Competing Plants in the Forest
Protecting forests from natural threats such as diseases and competing plants is an integral part of forest management. Plants competing for space, water, and nutrients can affect timber stand development, along with the biological diversity of native plant and wildlife species.
To sustain a healthy and productive forest ecosystem, it’s important to consider vegetation management practices using anIntegrated Vegetation Management (IVM) approach. IVM provides a way of managing vegetation through various methods, including herbicide application.
When properly applied, herbicides can be a safe and effective method for managing andcontrolling forest vegetation. When controlling unwanted trees,hack-and-squirt herbicide applications are among the most target-specific and economical means. Other types of herbicide applications include tree injections andbasal bark sprays.
Forest Regeneration
Allowing forests to regenerate after harvesting is an essential aspect of sustainable forestry. Various factors, however, can interfere with forest regeneration and, eventually, threaten forest sustainability. These includecompeting plants and deer populations.
Treating competing vegetation before harvest is crucial for preventing post-harvest problems such as impeded access and damage to desirable species. If deer damage to the forest is severe, reducing populations might be necessary. Methods to consider include seedling protectors, fencing, and deer repellents.
While most forests regenerate without human intervention, planting trees can accelerate the natural progression and enrich a newly regenerating forest with an uncommon species. Learn more about establishing wooded areas on rural properties with Penn State Extension’sGuide to Tree Planting Success.
On this page, forest landowners can access resources on controlling invasive and competing species. Information is also available on understandingbest management practices for PA forests and creating aforest stewardship plan.
Workshops$40.00
Managing Invasive Plants
When08/21/2025Length6 hoursEvent FormatIn-PersonManage invasive plants confidently! This full-day workshop covers ID, control strategies, sprayer calibration, herbicide mixing, and hands-on foliar application in natural areas and rights-of-way.
VideosApplying Herbicides in and Around Water
Length6:03This video explains the regulations pertaining to landowners in Pennsylvania about proper use of herbicides in aquatic settings.
VideosWho Can Apply Pesticides in Pennsylvania?
Length5:47Learn about the circumstances in which a non-certified applicator may legally purchase and apply pesticides in Pennsylvania.
ArticlesRosa Multiflora
La rosa multiflora (Rosa multiflora) es una especie exótica invasora catalogada como maleza nociva en Pensilvania. Este artículo incluye imágenes útiles para su identificación y ofrece recomendaciones prácticas para su control, entre ellas un calendario de manejo y periodos de aplicación de tratamientos.
ArticlesArbusto Ardiente
El arbusto ardiente (Euonymus alatus) es un arbusto invasor muy utilizado en jardinería. Este artículo muestra imágenes que ayudan a su identificación y ofrece recomendaciones para su control, incluyendo estrategias de control y calendario de tratamientos.
ArticlesCelastro
El celastro (Celastrus orbiculatus) es una enredadera leñosa, perenne e invasora. Este artículo presenta imágenes para facilitar su identificación y ofrece recomendaciones para su control, incluyendo un calendario de manejo y una tabla con tratamientos de control y tiempos sugeridos.
ArticlesAligustre
El aligustre (Ligustrum spp.) es un arbusto exótico invasivo. Este artículo muestra imágenes que ayudan a su identificación y ofrece recomendaciones para su control, incluyendo estrategias de control y calendario de tratamientos.
ArticlesMadreselva
La madreselva (Lonicera spp.) es un arbusto exótico invasivo. Este artículo muestra imágenes que ayudan a su identificación y ofrece recomendaciones para su control, incluyendo estrategias de control y calendario de tratamientos.
ArticlesHierba Zancuda
La hierba zancuda (Microstegium vimineum) es una gramínea anual invasora. Este artículo muestra imágenes que ayudan a su identificación y ofrece recomendaciones para su control, incluyendo estrategias de control y calendario de tratamientos.
ArticlesWavyleaf Basketgrass
This article describes wavyleaf basketgrass (Oplismenus undulatifolius), an invasive grass species, and provides identification and management.
ArticlesHierba Canasto de Hoja Ondulada
Este artículo se centra en la descripción de la hierba canasto de hoja ondulada (Oplismenus undulatifolius) y proporciona información sobre su identificación, manejo y control.
VideosInvasive Shrub Control Strategies
Length5:10Invasive shrubs are especially difficult to eradicate. Learn when and how to apply control measures, including herbicides, to control these undesirable plants.
WebinarsFree
Frontiers in Forest Health: Elm Zigzag Sawfly
WhenWatch NowLength1 hour, 15 minutesRecordedSep 9, 2024Event FormatOn-Demand | RecordedJoin us to explore the threat of the invasive elm zigzag sawfly, its impact on elm trees, ongoing research, and management strategies. Ideal for foresters, biologists, and tree owners.
VideosWhat Are Competing and Invasive Forest Plants?
Length1:53Competing and invasive forest plants often cause problems in forests after disturbances and timber harvests. Learn more about them before you harvest trees.
ArticlesIntegrated Forest Vegetation Management
To sustain healthy forest ecosystems it is necessary to consider multiple vegetation management practices using a systematic approach called Integrated Vegetation Management (IVM).
VideosBuckthorn: Accurate Identification
Length5:40Learn the distinguishing characteristics to help you accurately identify the invasive common (Rhamnus cathartica) and glossy buckthorn (Frangula alnus) shrubs.
VideosShrub Honeysuckle: Accurate Identification
Length4:17Learn the distinguishing characteristics to help you accurately identify the invasive shrub or bush honeysuckles (Lonicera spp.).
VideosPrivet: Accurate Identification
Length4:05Learn the distinguishing characteristics to help you accurately identify the invasive privet shrubs (Ligustrum spp.).
VideosOriental Bittersweet: Accurate Identification
Length4:49Learn the distinguishing characteristics to help you accurately identify the invasive Oriental bittersweet vine (Celastrus orbiculatus).
VideosMile a Minute: Accurate Identification
Length4:19Learn the distinguishing characteristics to help you accurately identify the invasive mile-a-minute vine (Persicaria perfoliata).
VideosGarlic Mustard: Accurate Identification
Length4:18Learn the distinguishing characteristics to help you accurately identify the invasive garlic mustard (Alliaria petiolata).
VideosCallery Pear: Accurate Identification
Length3:53Learn the distinguishing characteristics to help you accurately identify the invasive Callery or Bradford pear (Pyrus calleryana) tree.
ArticlesControl Invasive Shrubs in Spring with Basal Bark Herbicide Applications
Basal bark herbicide applications are targeted treatments you can make in spring to effectively control numerous invasive shrub species.
ArticlesThe Invasive Amur Corktree
The Amur Corktree is a species native to Asia that is considered an invasive species in Pennsylvania.
VideosBackpack Sprayer Calibration: Single-seedling Plot Applications
Length7:17Learn how to properly apply herbicide around a planted tree seedling with a backpack sprayer and how to determine the application rate for calculating the amount of herbicide to mix in your sprayer.
