Chapter Three Control and Identification of Invasive Species A Management Guide for Missouri Control and Identification of Invasive Species: A Management Guide for Missouri Introduction Throughout the United States, invasive plants are destroying native ecosystems and landscapes as they out-compete native plants for light, nutrients and moisture. Most of these invaders purposely were brought to the United States from other parts of the world for reasons that include ornamental value, livestock forage, erosion control, and food for wildlife. Some arrived accidentally as part of ship cargo, embedded on animals, cling- ing to clothing and other means. Whatever the means of entry, when these plants entered the U.S, their spread was unimpeded by natu- ral enemies such as grazing animals, insects, and diseases, that kept them in check in their homeland. Unregulated, they spread rapidly and wreak havoc on biodiversity as they overtake landscapes that once provided shelter and food for native wildlife. Among the worst offenders are bush honeysuckle, wintercreeper, autumn olive, sweet clover, Japanese honeysuckle, purple loosestrife, garlic mustard, sericea les- pedeza, Japanese hops, and Johnsongrass. The severity of infestation ranges from a few plants in a backyard to acres filled with dense populations of undesirable species. This guide includes control measures that can be used by homeowners and professional land managers. Homeowners likely will be able to use simple, mechanical methods, while professional land managers likely will resort to methods that call for herbicide application and use of large equipment. Herbicides CreateTop: Crown an application vetch planted strategy along interstate. before applying suggested in this manual are low risk and are herbicides.Middle: A volunteer Herbicides pulling should sweet clover be used after in con- not apt to contaminate groundwater. They junctionrainfall. Bottom: with other Honey methods, suckle thicket such in as hand break down rapidly in the environment and pulling,mature forest. mowing, controlled burning, reseed- have low toxicity to animals. ing and/or planting native alternatives. Introduction 3 Points to Remember When Controlling Invasive Species It is easier to control invasive species before native plants (see Chapter 1, Reconstructing a they get out of control, so control early. When Tallgrass Prairie). There are native alternatives dealing with a large population of an invasive available for each of the invasive plants men- species, begin removal at the edges and work tioned in this guide. inward. This reduces the rate of spread. Effective control may take several years. Personnel should be trained on herbicide and Scout annually for sprouts of invasive equipment use and should be able to identify plants and remove immediately. target and non-target species. Prevent contamination of streams, ponds, and lakes by selecting herbicides that This Guide Will: degrade rapidly in the soil and by using the right amount of herbicide for the job. Use approved herbicides when applying • help identify and effectively control near water and prevent spills, drips, and non- invasive species. target drift. • describe how to remove mechanically inva- sive species in small landscapes. • describe how and when to apply Do not buy invasive plants. Many nurseries herbicides for large landscapes. sell invasive plants such as wintercreeper, peri- winkle, burning bush, autumn olive, • suggest native plant alternatives for purple loosestrife and crown vetch. invasive species. • demonstrate how to manage land to pre- Replace invasive species with appropriate vent the invasion or re-invasion of invasive species. Terms to Know Invasive Species A plant or other organism, usually non-native that reproduces unchecked. It readily colonizes and thrives in habitats where it did not historically occur, causing changes in bio- Purple loosestrife taking over pond edge at Shaw Nature Reserve. 4 Control and Identification of Invasive Species: A Management Guide for Missouri diversity and ecological functioning of those reclaim the area. To prevent reinfestation habitats. of invasive species, plant desirable native spe- cies or sow an appropriate native seed mix in Non-native/Exotic Species these areas. After the initial removal, diligently An organism that occurs in an area because remove resprouting invasive seedlings as it was brought there, intentionally or they appear. The smaller the seedling, the accidentally, by humans. Most exotic species do easier it is to remove by hand. See section on not become invasive, and some may occur in revegetation to prevent an area for many years before becoming inva- secondary invasion of weeds. sive. Surfactants Native Species Also called adjuvants, nonionic surfactants, A plant or other living organism that occurs in or spreader stickers. A barrier to herbicide a geographic area without human influence. absorption into plants is the cuticle, a waxy layer that covers leaves and stems. Herbicide Its purpose is to prevent water loss during Chemicals formulated to kill plants, with low dry periods. Surfactants added to herbicides or insignificant toxicity to other organisms. improve absorption through the cuticle and Broad-spectrum herbicides such as Roundup help herbicides adhere to leaves. You may are toxic to virtually all plants, while broadleaf need to add a surfactant to your herbicide. herbicides kill only or most effectively broa- Read labels to determine if a product already dleaf plants, leaving grasses and related plants contains surfactants. unharmed. There also are grass- specific herbicides. Mechanical Control Methods Seed Bank of Invasive Species Some seeds live in the top layer of soil for decades, creating a seed bank. When parent Shrubs plants are removed, a new crop of seedlings Bush honeysuckle, Privet, Autumn olive, sprout quickly from the seed bank and Pulling medium-size Bush honeysuckle with a weed wrench. 5 Burning bush, Buckthorn, Multiflora rose, to the opposite hand when using hand pruners. Japanese knotweed. Practice appropriate safety measures at all times. Trees Stems more than an inch in diameter typically require a handsaw, chain saw, or a string trim- Amur maple, Tree of heaven, Golden mer outfitted with a circular saw blade. Chain- raintree, Lacebark elm, Eastern red cedar. saw and circular-saw use require training and proper safety gear (helmet, ear and eye pro- Newly emerged seedlings of woody plants tection, leg and ankle protection, and sturdy are easily hand-pulled when soil is moist leather boots). (a day or two after rainfall). Stems less than one inch in diameter can be cut with sharp hand pruners or loppers*. Then use a weed wrench, winch, or come-along to For large shrubs and trees, remove trunks yank the roots out of the ground. and stems first. Then roots are more easily If this is not an option, dig out roots with hand removed. Leave 1-3 feet of stem attached tools or rent a stump grinder. to Hand prunners, hand saw, and loppers. Top: Hand-pulling Bush honeysuckle after a thesoaking roots rain. to use as a handle or lever and use a weedBottom: wrench, Use of weed winch, wrench or come-along for larger stems after a *The most common injury among horticulturists tosoaking yank rain. out the roots. If this is not an option, and volunteers at Shaw Nature Reserve is a cut dig out the roots with hand tools 6 Control and Identification of Invasive Species: A Management Guide for Missouri or rent a stump grinder. a minimum. Disturbed ground quickly grows with weeds, so have a native plant seed mix ready to sow in these areas. (See section on revegetation to prevent secondary invasion of weeds.) Large-scale removal (more than an acre) Woody Vines requires a skid-steer and front-mounted Japanese honeysuckle, Wintercreeper, grapple or bull hog to remove mature shrubs Periwinkle, English ivy, Asiatic bittersweet – roots and all. Some grapples grab the stems and pull up, others grab the roots and pry out. Newly emerged seedlings of woody plants Skid-steer removal should be done only when are easily hand-pulled when soil is moist the ground is dry to keep soil disturbance to (a day or two after rainfall). A circular saw or chain saw are used in larger areas Top: Root grapple on a skid-steer pries large plants and require protective equipment and training. out of the ground. Bottom: Bull hog on a skid-steer shreds plants from top to bottom. 7 to effectively control dense patches and It is difficult to control small areas of woody their seed bank when herbicide is not used. vines by mechanical methods. When carpets of these vines occur, smother them with black plastic, tin, rubber mats, or a 12-inch layer of Perennial Legumes wood chips. Because these materials can be expensive or hard to come by, they are useful Sericea lespedeza, Bird’s foot trefoil, only on small areas and should remain in place Crown vetch, Red clover, White clover for a year to be effective. Non-herbicide methods to control these A second method for small areas is to cut out difficult species generally are not effective. the plants with a sharp garden spade. Cut and Plants and the top 3inches of topsoil peel back the carpet of vines in small sections. should be dug and removed from the site Because they are shallow-rooted, they come to effectively control dense patches of the up easily. Large sections of carpet, however, listed species and their seed banks* when her- can be heavy and difficult to handle. Stem and bicide is not used. Watch for missed root seg- root segments will ments and remove immediately. be missed and need to be removed at a later *Sericea lespedeza, Bird’s foot trefoil, Red clover, and date. Crown vetch have seed banks in the top few inches of topsoil that are viable for as many as 20 years. In large areas a skid-steer can be used to uproot large sections of invasive vines.