A Management Guide for Invasive Plants in Southern Forests James ...

8What Is the Need for Selectivity?Selectivity means targeting invasive plants while minimizing damage to neighboring native plants. You can controlspecific plant species with a selective herbicide, or you can apply a nonselective herbicide selectively to treat onlytargeted invasive plants. As an example, you can use a broadcast herbicide on a prairie that is 99 percent invasivegrasses. In some cases, the native soil seed bank will reestablish itself. If the prairie has been manipulated for manyyears, you may need to seed with native grasses. If the prairie contains a wide variety of native species intermixedwith targeted nonnative species, you must choose a more selective herbicide or application method as well as burningand 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 sizeand growth form of the invasive species, and the longevity of the invasive species’ viable seeds or other propagulesin 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 thathas 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 ahigh infestation of large Chinese privet (L. sinense Lour.) under a desirable hardwood overstory, you’ll need to usemethods appropriate for woody plant control that safeguard the hardwoods. On the other hand, if the privet is 1 to 2years old or has been cut to resprout, you can more easily apply foliar applications of a nonselective herbicide duringthe 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 timefor applying control treatments as well as revegetation actions. If you know the annual cycle of growth initiation, floweringand fruiting, drought responses, and periods of dormancy, you can plan the most effective approach. By applyingherbicides, burning, and cutting at the appropriate stage in a plant’s seasonal cycle, you can increase effectiveness andselectivity as well as reduce the need for additional retreatments. Other timing issues concern availability of labor andcontract applications, number of treatments necessary in a season, and access periods for wetlands, high-elevationsites, 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, volunteerscan apply herbicide treatments, but in most places, volunteers use only manual or mechanical control methodssuitable for small infestations. In-house and contract workers often are the best trained in knowing how to handle largerinfestations 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 ofyour costs in light of realistic objectives. Once you enact a plan, understand that disruption in scheduled treatmentscan cause major setbacks and even loss of your prior work. If you use ineffective treatments, like only cutting woodyinvasive plants without applying herbicide to the stumps, you can accrue large costs over the long run. Using only themost efficient methods is a wise investment in safeguarding a natural heritage for future generations.