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.
Answering the following questions will help you develop a plan that considers appropriate tools, timelines, costs, and outcomes.
What Is the Long-Term Plan for the Site?
Control methods can change dramatically based on the site’s planned uses. For example, if the long-term plan is to keep the site cleared of all tall vegetation, then a less selective and less expensive approach can be used. If you need to protect indefinitely a site that contains many desirable or rare species, then consider a more selective long-term treatment and monitoring plan.
What Is the Need for Selectivity?
Selectivity means targeting invasive plants while minimizing damage to neighboring native plants. You can control specific plant species with a selective herbicide, or you can apply a nonselective herbicide selectively to treat only targeted invasive plants. As an example, you can use a broadcast herbicide on a prairie that is 99 percent invasive grasses. In some cases, the native soil seed bank will reestablish itself. If the prairie has been manipulated for many years, you may need to seed with native grasses. If the prairie contains a wide variety of native species intermixed with targeted nonnative species, you must choose a more selective herbicide or application method as well as burning and other rehabilitation treatments.
What Is the Intensity of Infestation?
The intensity of infestation is determined by the relative area and height of occupation, the infestation’s age, the size and growth form of the invasive species, and the longevity of the invasive species’ viable seeds or other propagules in the soil. These factors can dramatically affect the methods, timing, persistence, and costs of control and site rehabilitation. For example, you’ll need to spend considerable time and effort treating an invasive multi-stemmed tree that has grown at high infestation levels, has grown on the site for a decade or more, and has long-lived residual seeds. You’ll need less time and effort for scattered low-growing annual invaders with few residual seeds.
The target plant’s size will dictate your treatment methods and limit application options. For example, if you have a high infestation of large Chinese privet (L. sinense Lour.) under a desirable hardwood overstory, you’ll need to use methods appropriate for woody plant control that safeguard the hardwoods. On the other hand, if the privet is 1 to 2 years old or has been cut to resprout, you can more easily apply foliar applications of a nonselective herbicide during the dormant season—meaning you’ll spend less time and herbicide and, thereby, save both effort and cost.
How Does Timing Affect Control Methods?
Understanding the life cycle of invasive plants helps the landowner, manager, and applicator select the optimum time for applying control treatments as well as revegetation actions. If you know the annual cycle of growth initiation, flowering and fruiting, drought responses, and periods of dormancy, you can plan the most effective approach. By applying herbicides, burning, and cutting at the appropriate stage in a plant’s seasonal cycle, you can increase effectiveness and selectivity as well as reduce the need for additional retreatments. Other timing issues concern availability of labor and contract applications, number of treatments necessary in a season, and access periods for wetlands, high-elevation sites, parks, and military reservations.
What Type of Labor Will Work on the Site?
In-house, contract, and volunteer labor all have different strengths and distinct disadvantages. In some States, volunteers can apply herbicide treatments, but in most places, volunteers use only manual or mechanical control methods suitable for small infestations. In-house and contract workers often are the best trained in knowing how to handle larger infestations that require special equipment, precise herbicide applications, and other approaches presented in this guide.
How Important Is Cost?
The cost of a project is directly related to treatment method, intensity of infestation, plants and areas that need safeguarding, and availability of resources. Cost-share and incentive programs can decrease costs for the landowner, but the number and years of retreatment might be restrictive. Once you formulate a plan, make careful estimates of your costs in light of realistic objectives. Once you enact a plan, understand that disruption in scheduled treatments can cause major setbacks and even loss of your prior work. If you use ineffective treatments, like only cutting woody invasive plants without applying herbicide to the stumps, you can accrue large costs over the long run. Using only the most efficient methods is a wise investment in safeguarding a natural heritage for future generations.
