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 as various 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 as mile-a-minute and oriental bittersweet can create dense foliage that blankets and gradually suffocates native vegetation.
Other noxious weeds found in Pennsylvania forests include the Japanese barberry woody plant, multiflora rose, and various privet shrubs. Tree-of-heaven is another rapidly growing invasive tree and noxious weed. The tree’s extensive root system makes it difficult to control, but applying 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 an Integrated 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 and controlling 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 and basal 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 include competing 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’s Guide to Tree Planting Success.
On this page, forest landowners can access resources on controlling invasive and competing species. Information is also available on understanding best management practices for PA forests and creating a forest stewardship plan.
- Webinars
Free
Frontiers in Forest Health: Elm Zigzag Sawfly
When Watch NowLength 1 hour, 15 minutesRecorded Sep 9, 2024Event Format On-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. - Videos
What Are Competing and Invasive Forest Plants?
Length 1:53Competing and invasive forest plants often cause problems in forests after disturbances and timber harvests. Learn more about them before you harvest trees. - Articles
Integrated 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). - Videos
Buckthorn: Accurate Identification
Length 5:40Learn the distinguishing characteristics to help you accurately identify the invasive common (Rhamnus cathartica) and glossy buckthorn (Frangula alnus) shrubs. - Videos
Shrub Honeysuckle: Accurate Identification
Length 4:17Learn the distinguishing characteristics to help you accurately identify the invasive shrub or bush honeysuckles (Lonicera spp.). - Videos
Privet: Accurate Identification
Length 4:05Learn the distinguishing characteristics to help you accurately identify the invasive privet shrubs (Ligustrum spp.). - Videos
Oriental Bittersweet: Accurate Identification
Length 4:49Learn the distinguishing characteristics to help you accurately identify the invasive Oriental bittersweet vine (Celastrus orbiculatus). - Videos
Mile a Minute: Accurate Identification
Length 4:19Learn the distinguishing characteristics to help you accurately identify the invasive mile-a-minute vine (Persicaria perfoliata). - Videos
Garlic Mustard: Accurate Identification
Length 4:18Learn the distinguishing characteristics to help you accurately identify the invasive garlic mustard (Alliaria petiolata). - Videos
Callery Pear: Accurate Identification
Length 3:53Learn the distinguishing characteristics to help you accurately identify the invasive Callery or Bradford pear (Pyrus calleryana) tree. - Articles
Control 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. - Articles
The Invasive Amur Corktree
The Amur Corktree is a species native to Asia that is considered an invasive species in Pennsylvania. - Articles
Honeysuckle Disease
Informational table showing disease name, symptoms, pathogen/cause, and management of Honeysuckle diseases. - Videos
Backpack Sprayer Calibration: Single-seedling Plot Applications
Length 7:17Learn 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. - Webinars
Free
Managing Common Invasive Shrubs
When Watch NowLength 1 hourRecorded Nov 15, 2023Event Format On-Demand | RecordedIn this talk, you will learn about common invasive shrubs in Pennsylvania and how to manage them. - Articles
'Tis The Season - Winter Invasive Plant Control
A number of plant growth forms are susceptible to control measures in the dormant season. This is a useful time to manage winter annuals, biennials, non-suckering woody species, and woody vines. - Videos
Autumn Olive: Accurate Identification
Length 3:23Learn the distinguishing characteristics to help you accurately identify the invasive autumn olive (Elaeagnus umbellata) shrub. - Videos
Burning Bush: Accurate Identification
Length 3:59Learn the distinguishing characteristics to help you accurately identify the invasive Burning bush (Euonymus alatus) shrub. - Videos
Japanese Barberry: Accurate Identification
Length 3:58Learn the distinguishing characteristics that will help you accurately identify the invasive Japanese barberry (Berberis thunbergii). - Videos
Japanese Knotweed: Accurate Identification
Length 3:29Learn the distinguishing characteristics you can use to accurately identify the invasive Japanese knotweed (Fallopia japonica). - Videos
Japanese Stiltgrass: Accurate Identification
Length 4:11Learn the distinguishing characteristics to help you accurately identify the invasive Japanese stiltgrass (Microstegium vimineum). - Videos
Multiflora Rose: Accurate Identification
Length 4:49Learn the distinguishing characteristics to help you accurately identify the invasive multiflora rose (Rosa multiflora). - Videos
Backpack Sprayer Calibration for Spot Applications
Length 4:09Learn how to properly spray herbicide for a spot application with a backpack sprayer, and how to determine the application rate for calculating the amount of herbicide to mix. - Videos
Backpack Sprayer Calibration for Broadcast Applications
Length 5:20Learn how to properly spray for a broadcast herbicide application with a backpack sprayer, and how to determine the application rate for calculating the amount of herbicide to mix. - Articles
One Herbicide Mix to Do It All (Almost)
Using a mixture of the herbicides glyphosate plus triclopyr provides a broadly effective and low-risk treatment for invasive plant species