Introduction: Plant Management Techniques

Many factors influence the identification and selection of promising techniques for eliminating invasive species. Each eradication effort presents its own specific opportunities and constraints. Among the factors of concern to this process are:

plant life cycle stages;
seasonality;
environmental conditions such as soil and air moisture content, photoperiod, temperature, etc.;
exposure of the area to wind energy;
site topography;
size of area colonized by the invasive species;
size and level of training of the assigned workforce;
proximity of desirable native species to the area of infestation,
available funds, and others.

 

There is no simple formula that fits all circumstances for a given species, or all species within a given area, such as Taylor Point. Each invasive species removal project must be designed on a case-by-case basis.

The Taylor Point Restoration Association (TPRA) has enlisted a variety of scientists and environmental managers to help us develop promising invasive plant removal strategies. These experts provide guidance and training to our leadership and our volunteers, and help us assess our effectiveness.

As we proceed to develop and implement invasive species removal strategies and endeavor to create a more favorable environment for native species, it is incumbent on us to:

adhere to our plans;
observe the results of our efforts season-to-season, and year-to-year;
evaluate, and document the effectiveness of our strategies;
ascertain the major factors influencing our successes and our setbacks; and finally

to adjust our techniques in response to these observations and assessments as we move forward through and beyond the decade.

As we enlist more volunteers and train more community members in the management techniques employed at Taylor Point, we rely on our volunteers achieving a fundamental understanding of the basic terms and general removal processes from which our strategies are drawn. For this reason we have provided in the Taylor Point Plant Atlas, this section on plant management. This presentation provides only bare bones and broad brush discussions of the available methods and the circumstances under which various methods may hold promise. This presentation is not intended to prescribe methods for a given species or habitat. Rather its purpose is simply to help new recruits familiarize themselves with the basic mechanisms and the basic vocabulary of plant management techniques.

The manual and mechanical control techniques that will be used at Taylor Point to remove invasive plants are described in the 2017 CRMC Buffer Zone Management Permit Request and Assent. These methods are extremely specific and minimize damage to desirable plants. They also are labor and time intensive. Removal techniques will most likely need to be repeated. Invasive plant populations will need to be monitored to assess the effectiveness of removal methods.

The information and tables presented below are drawn from two major sources. The first source is material developed by Carl Sawyer, former Research Associate with the RI Agricultural Experiment Station and former URI Plant Sciences Researcher, who compiled chemical control information used by the URI Invasive Plant Management Certification Program ( URI IPMCP ). The second source cited in the tables that follow is the US Fish and Wildlife Service, National Refuge System planning and guidance for managing invasive plants. The information presented below provides a basic introduction to plant management techniques and applications to be used simply as a starting point for those who are interested in participating in TPRA projects.

Techniques for Removing Invasive Species 

This table defines removal methods, appropriate target plants for each method, and other considerations concerning when and how each method should be used.

METHOD	APPROPRIATE TARGET	KEY CONSIDERATIONS
Pulling: remove the plant from the soil; work gloves are recommended; pulling tools may be used for large plants, shrubs, or trees.	-Tap-rooted and shallow-rooted terrestrial plants (particularly annuals) unable to resprout from roots or other vegetative organs can be hand pulled; larger plants can be pulled with tools such as a Weed Wrench.	-Pull when plants are big enough to grasp and soils are damp or loose enough to release roots. -Labor intensive, and may need to be repeated. -Useful in small areas and areas inaccessible to large equipment. -Remove plants off-site if seeds can spread. -A very selective technique.
Hoeing: scrape seedlings from the soil or cut off small plants just below the upper layer of soil.	-Annual and perennial plants that are unable to sprout from roots or other vegetative organs	-Hoe seedlings or small plants -Labor intensive, and may need to be repeated. -Useful in small areas and areas inaccessible to heavy equipment -A very selective technique
Tilling: break, cut, or uproot plants from the soil and alter soil environment.	-Annual plants -Shallow-rooted perennials	-Till when weather is hot and soils are dry to reduce chances of resprouting or seed germination -With perennials, till when plant carbohydrate reserves are low (e.g., early spring) -Repeated tilling depletes soil seedbanks and carbohydrate reserves of perennial plants -A nonselective technique; results in large areas of disturbed soil.
Mowing: cut or shred above ground vegetation.	-Plants that reproduce primarily by seed	-Mow during the flowering stage of target plants, before seed development and, ideally, when desired plants are dormant -Repeated mowing may be required to prevent seed production -A nonselective method
Cutting: lop off plants at ground level using saws, axes, and/or loppers.	-Trees, vines, and woody plants	-Timing can minimize resprouting; ideally, cut under drought conditions -Labor intensive -Grinding remaining stumps or painting them with herbicides may prevent re-sprouts -A very selective method
Girdling: cut away a strip of bark several inches wide around trunks of trees or woody vines to interrupt the flow of nutrients to active growing points.	-Trees and shrubs that do not re-sprout	-Labor intensive -Results in standing dead trees and shrubs -A very selective method.
Mulching: physically impede plant growth and exclude light from germinating plants.	-Small annual plants	-Mulch early in the growing season -Use in relatively small areas -A somewhat selective method, depending on mulch placement -Use weed-free mulches
Soil solarization: cover damp soil to trap heat and increase soil temperatures to levels that are lethal to plants and seeds; use clear or black plastic.	-Winter annuals that germinate in cool conditions are most susceptible -Small-seeded species	-Requires extended hot, sunny days -Appropriate for defined areas with small populations -May alter soil properties -A nonselective method

Herbicide Use

The chemical control techniques will not be used at Taylor Point to remove invasive plants. Herbicide use is not allowed under the 2017 Assent. These methods are however called out by some plant profiles and are included here to explain, when and how they may be selected and used. Herbicide application can efficiently and effectively suppress or kill unwanted plants. When used, herbicides must be used judiciously, safely, and in a way that minimizes adverse effects on nontarget resources. It is essential that before procuring and before applying herbicides, the information, instructions, and cautions presented on each product’s label are carefully reviewed and strictly followed. As in manual and mechanical removal techniques, herbicide application may need to be repeated, and invasive plant populations will need to be monitored to track the effectiveness of the removal methods used.

General Guidelines for Herbicide Application

1. Wait until bud stage or later when treating perennial weeds with systemic herbicides. This is when maximum translocation of metabolites and herbicides back to root and storage tissues occurs.
2. Treat annual weeds at the youngest stage possible but after most or all of seeds have germinated if using a postemergent product. Contact herbicides are usually adequate for post emergent applications. If using a preemergent, be sure to get material on before any germination has occurred.
3. Don’t treat when plants are stressed by drought or high temperatures.
4. Don’t remove leaf area by mowing prior to a foliar treatment.
5. Most pre-emergent herbicides need to be activated by a specified amount of rainfall or irrigation within a specified number of days.
6. Most post-emergent herbicides have a specified rain-free period in order to be effective.
7. Treat the cambial layer of cut stems and stumps immediately after cutting. Avoid cutting and treating during periods of sap flow, typically late winter and early spring.

 

This following table defines the methods, appropriate plant targets and other considerations for when and how each method should be used

Chemical Control Techniques

Chemical Method	Appropriate Target	Key Considerations
Frill or Hack and Squirt: Cut or drill tree then immediately apply herbicide to the cut.	-This method is often used to treat woody species with large, thick trunks	-Because the herbicide is placed directly onto the thin layer of growing tissue in the trunk (the cambium), there is little risk of herbicide movement to non-target plants.
Cut Stump: Cut down the tree or shrub, and immediately spray, paint, or squirt herbicide on the exposed cambium (living inner bark) of the stump with relatively concentrated herbicide.	-This method is often used on woody species that normally re-sprout after being cut. -Avoid applications during periods of spring sap-flow.	-The herbicide must be applied to the entire inner bark (cambium) within minutes after the trunk is cut. -The cut stump treatment allows for a great deal of control over the site of herbicide application, and therefore, has a low probability of affecting non-target species or contaminating the environment. It also requires only a small amount of herbicide to be effective. -The herbicide can be applied using spray and squirt bottles, or even paint brushes.
Foliar Herbicide - Wick/Wipe-on Applicators: Use a sponge or wick on a long handle to wipe herbicide onto foliage.	-This method allows for the isolation of a specific plant for management.	-Use of a wick eliminates the possibility of spray drift or droplets falling on non-target plants. However, herbicide can drip or dribble from some wicks. -A surfactant is often needed to enable the herbicide to penetrate the plant cuticle, a thick, waxy layer present on leaves and stems of many plants.
Foliar Herbicide - Spot Applicators: Spray herbicide directly with a spray bottle or backpack onto target plants only, and avoid spraying other desirable plants.	-These methods apply herbicide directly to the plant leaves. -Sprays are most useful for vegetation that is relatively close to the ground.	-These applicators range in size and can target very small plants or parts of plants. -Spays can provide uniform coverage of soils or foliage. -A disadvantage is of spraying is the potential for injury to non-target vegetation from drift. -A surfactant is often needed to enable the herbicide to penetrate the plant cuticle, a thick, waxy layer present on the leaves of most plants.
Basal Bark: Apply a 6 to 12 inch band of herbicide around the circumference of the trunk of the target plant, approximately one foot above ground.	-The basal bark treatment works best on young trees with smooth bark. -It is usually not effective against older plants with thick corky bark.	-The width of the sprayed band depends on the size of the plant and the species’ susceptibility to the herbicide. -The herbicide can be applied with a backpack sprayer, hand-held bottle, or a wick. During summer, treatment is best carried out in the mornings, which tend to be cooler. -This treatment is often used during the dormant season. -Herbicides are often carried in oil or diesel fuel to facilitate penetration of the bark.
Injection: Injected herbicide into woody trunks	-Plants with woody trunks	-Herbicide can be injected into the trunk of a tree using a specialized tool. It is a convenient way of applying herbicide and requires minimal preparation or clean up. In addition, it is an easy and safe way to apply herbicides with minimal exposure.
Stem Injection: Inject hollow stem or cut stem and pour herbicide into hollow stem.	-Plants with hollow stems such as Phragmites and Japanese knotweed.	-The herbicide used must specifically be labeled for injection. -This method is effective on small stands. -This method is impractical on significant stands.
Spreading Granular or Pelleted Formulations: Spread herbicide with a rotary or drop spreader.	-For small areas, drop or use a rotary spreader on wheels -For large areas use tractor mounted rotary spreader.	-Regardless of which herbicide is applied, the product must be applied accurately and uniformly to achieve effective weed control and to avoid over-application, which may injure crops.

 

 

Definitions/Herbicide Terminology

Selective Herbicide: Toxic to some plant species while non-toxic to others.

Non-Selective Herbicide: Generally toxic to most plants

Contact Herbicide: Causes localized injury to plant tissue where contact occurs

Translocated Herbicide: Moves within the plant. Usually refers to herbicides that, when applied to foliage, move down to underground tissues via phloem, however some products may be applied to soil where they are then translocated to leaf tissue. Synonymous with systemic.

Pre-emergent Herbicide: Applied to the soil prior to weed seed germination.

Post-emergent Herbicide: Applied to weeds at some specified time after plants have emerged from the soil

Residual Herbicide: Prevents plant growth for an extended period of time. May have both pre- and post-emergent activity. Some residual herbicides are effective for only a few months, while others may be effective for several years. Herbicides with long activity are sometimes referred to as soil sterilants.

Adjuvant: Any additive used with an herbicide that enhances the performance or handling of the herbicide, e.g.: surfactants, anti-foaming agents, drift control materials, colorants.

Surfactant: A material that improves the emulsifying, dispersing, spreading, wetting or other surface-modifying properties of liquids.

Tank mix: Combination of two or more pesticides or agricultural products in the spray tank at the time of application.

Formulation: Herbicide preparation supplied by the manufacturer. May refer to a product’s physical state (powder, granule, emulsifiable concentrate, etc.) or its chemistry (amine, ester, salt, etc.)

 

The basic purpose of the Plant Atlas is to provide background information to support the case-by-case selection and use of removal methods for invasive plants, as well as to support decisions regarding revegetation and protection of native species. The Atlas is grounded in the assessment of existing conditions at Taylor Point as presented in the Taylor Point Plan of March of 2017. By  cataloging each plant in the plant population by type, size, and location, and providing rudimentary information regarding plant life cycle and environmental requirements, TPRA has tried to provide useful tools for management strategies and implementation. This information also allows the Taylor Point Restoration Association to assign priorities for the management of existing populations and to be ever vigilant in the early detection of new populations of invasive plants.

For more in-depth discussions, we recommend consulting the following sources:

US Fish and Wildlife Service (FWS). National Refuge System
Managing Invasive Plants
Concepts, Principles, and Practices
US Fish and Wildlife Service Invasive Training

The Nature Conservancy
Weed Control Methods Handbook: Tools & Techniques for
Use in Natural Areas
Nature Conservancy Weed Control Methods

Invasive plant management certification program (ipmcp)
URI Cooperative Extension