Invasive Exotics and Herbicide Application

Transcription

1 Invasive Exotics and Herbicide Application I. Lesson Plan Outline 3 II. Invasive Exotics a. Definition 4 b. Characteristics 5 c. Common Invasive Exotics of MN i. Birdsfoot Trefoil 6 ii. Black Locust 7 iii. Buckthorn 8 iv. Canada Thistle 10 v. Crown Vetch 11 vi. Garlic Mustard 12 vii. Honeysuckle 13 viii. Leafy Spurge 14 ix. Purple Loosestrife 15 x. Reed Canary Grass 17 d. Control Methods i. Manual and Mechanical Weed Pulling 2. Mowing / Cutting /Sawing 3. Girdling 4. Mulching / Sheet Mulching ii. Biological Control Classical 2. New Association or Neoclassical 3. Conservation, Augmentation, or Inundation iii. Prescribed Burns 22 iv. Chemical Application 1. Application Techniques 22 a. Foliar Application b. Basal Bark Treatment c. Cut Stump Treatment 2. Instruments for Application 24 a. Backpack Sprayer b. Hand Sprayer c. Dauber

2 III. Herbicides a. Introduction 25 b. History 25 c. Regulation 26 d. Label information 26 e. Safety 28 i. PPE ii. Procedures for Herbicide Use f. MCC Applied Herbicides 32 i. Garlon 3A & Garlon 4 ii. Roundup & Rodeo iii. Transline iv. 2, 4-D IV. Group Activity Sheet: Herbicide Application Scenarios 35 V. Glossary of Terms 36 2

3 Objectives: CMs will define and name characteristics of invasive exotics CMs will be able to identify common invasives in MN CMs will be familiar with multiple control methods and their relative effectiveness CMs will be able to demonstrate three herbicide application techniques with corresponding application tools CMs will examine herbicide label components CMs will identify required PPE for herbicide application CMs will be familiar with herbicides commonly used by MCC Materials: Invasive Exotics & Herbicide Application Branches, leaves, and/or flowers from common invasives in your district or ID book (if not available, photos and descriptions of common MN exotics are included in the Invasive Exotics and Herbicide Application chapter) Backpack / hand sprayers / dauber and water for herbicide application demonstration PPE for herbicide application demonstration Multiple herbicide containers for crews to examine labeling Copies of Herbicide Application Scenario Sheet (1 sheet per crew) Supplemental materials are contained in the Invasive Exotics and Herbicide chapter Total Time Estimate: 2 hrs. 45 min. Procedure: Group can be district-sized if break into crews for invasive species identification, herbicide application demonstration, label examination, and scenario activity. Time (min.) Activity/ Discussion Description/ Instructions 10 min. Introduction to Define terms indigenous / exotic / invasive / invasive exotic Invasive Exotics Discuss characteristics of invasive species 30 min. Discuss exotics that are common to your district. Identify common Discuss identification characteristics (have twig, leaves, flowers of invasives in MN invasives available or hike to prime location to facilitate ID) Control Methods Discuss manual & mechanical, biological, prescribed burning and 45 min. Discussion & chemical application as methods of control. Herbicide Application Demonstrate the three herbicide application techniques with Demonstration backpack / hand sprayers / daubers and water (with proper PPE). 20 min. Herbicide regulation Discuss EPA regulation of herbicides and label information. & labeling Use herbicide containers to examine the components of a label. 20 min. Herbicides used by Discuss commonly used herbicides and associated application MCC technique, predominant use, and health/environmental impacts. Divide CMs into crews to discuss the herbicide application 25 min. Herbicide Application scenarios provided. Regroup to discuss what herbicide (if any) Scenario Sheet they recommended, application technique, and how to mitigate any health/environmental concerns. 15 min. Q&A Conclude with questions and follow up with information requests 3

4 Invasive Exotics INTRODUCTION If left unchecked, invasion by exotics may severely and irrevocably alter the biological function and economic value of a particular area by displacing native vegetation, decreasing productivity, altering nutrient cycling and soil structure, and disrupting natural disturbance and succession patterns. Invasive proliferation degrades already threatened native prairies and woodlands and eliminates cover and food sources for native fish and animals. Invasives cause problems for those who use natural resources, whether for recreational use of land or waters or industrial use of public waters. Indigenous: Definitions A species is known as indigenous to a particular area if it originates naturally without having been either intentionally or inadvertently introduced. Indigenous species have well-established ecological niches within their natural ranges, and are well adapted to local abiotic and biotic factors, such as climate, soil, and species interactions Exotic: Species that have been artificially introduced, or moved, by human activities to a location where they do not naturally occur are termed exotic, nonnative, alien, or nonindigenous. Some exotic species were intentionally introduced for their agricultural utility or for aesthetics, such as Buckthorn and Purple Loosestrife. Unintentional introductions generally result from contaminated imports. Species are carried on barges, boats and trailers, animals, vehicles, commercial goods, packing materials, produce, and in ballast water of ships. Invasive: When species cause ecological or economic problems, they are termed invasive or harmful exotic species. Invasives are typically nonnative species. However, a native plant may start acting like an invasive species due to some human-caused habitat change (such as a change in water quality because of agricultural runoff or the abnormal suppression of fire). Invasives are a major cause of biological diversity loss throughout the world, second only to habitat destruction. Invasive Exotics: Any species, including its seeds, eggs, spores, or other biological material capable of propagating that species, that is not native to that ecosystem; and whose introduction does or is likely to cause economic or environmental harm or harm to human health. 4

5 A number of invasive plant species contribute to habitat alteration and degradation by outcompeting native species. Without the natural controls (predators, competitors, parasites, diseases) inherent in their native regions that keep their populations in check, exotic species become invasive because of their tendency towards rapid growth and maturity, prolific seed production and dispersal over large areas, and highly successful germination and colonization. Thus, they are able to displace native plants by out-competing for essential resources. Characteristics of Invasive Species Below are a few common characteristics of invasive species. Productivity: More seeds mean more seedlings. Purple loosestrife and white and yellow sweet clovers produce hundreds of thousands of seeds per plant. Dispersal: Invasive plants often have seeds or other propagules that are easily spread by people, wind, water, or wildlife. They can establish in new locations far from their parent plants. Eurasian milfoil fragments can be carried on boats and trailers to new locations. Buckthorn and honeysuckle berries are eaten by birds, and are later deposited where they fly. Purple loosestrife seeds can be carried by wind and water. Growth period or seasonal advantages: Buckthorn, when planted in North America, leaf out early in the spring and stay green long after most deciduous trees in autumn. Buckthorn's longer growing season means faster growth to maturity, an advantage over native shrubs. Lack of natural controls: When a species is transferred to a new location outside its natural range, the insects, diseases, or other pests that help control it may be left behind. The degree to which an invasive exotic possesses these characteristics typically correlates to the degree to which it is widespread and troublesome. Conservation experts estimate that in the US, Invasive plant infestations cover 100 million acres (an area twice the size of Delaware) and are spreading at a rate of 14 percent per year. 5

6 COMMON INVASIVE EXOTICS OF MINNESOTA Birdsfoot trefoil (Lotus corniculatus) Appearance: Perennial herbaceous plant, tall; the clover-like plant has a sprawling growth pattern. Leaves: Three clover-like leaflets on a short stem with two additional leaflets at the base of the stem. Flowers: Yellow pea-like flowers occur typically in flat-topped clusters of 3-12, 0.5 long flowers which are sometimes tinged with red. Blooms most of the summer. Seeds: One-inch long brown seed pods are produced in clusters, resembling a bird s foot. Ecological Threat: Birdsfoot trefoil forms dense mats choking and shading out most other vegetation. It grows best in the Midwest and is most problematic in prairies and disturbed open areas, such as roadsides. This European species has been introduced to the U.S. and Canada for livestock forage and erosion control along roadsides. It is still sold commercially. Control Methods: Mechanical: Mowing frequently at a height of less than 2" for several years, (this will be stressful to native plants as well). Chemical: Spot spraying affected areas after plants re-green from a burn or mowing, with clopyralid + surfactant + dye (Transline). If no mechanical control is used, spray plants in spring when young and actively growing. The selective herbicide, Transline, also affects native plants of the sunflower and pea families. **Prescribed burns increase Birdsfoot trefoil seed germination, increasing proliferation in native prairies. Thus, prescribed burning without herbicide application is not an adequate means of control. 6

7 Black locust (Robinia pseudoacacia) Appearance: Fast growing tree up to 75' in height with deeply furrowed flat-topped ridges. Seedlings and root sprouts have long thorns and grow rapidly. Leaves: Alternate, pinnately compound (leaflets on both sides of a common stalk) with 7-21 elliptic, untoothed leaflets, with one leaflet at the tip. A pair of short, sharp thorns sit at the base of each leaf where it is attached to the twig. Flowers: Fragrant, drooping white flowers arranged in elongated clusters appear in late May and June. Seeds: Seed pods are smooth, 2-4" long; they mature in September and persist through winter. Roots: Extensive fibrous root system. Spreads vegetatively through root suckering and runners. Ecological Threat: Invades primarily disturbed habitats, degraded wood, thickets and old fields crowding out native vegetation of prairies, oak savannas and upland forests, forming single species stands. It reproduces vigorously by root suckering and stump sprouting forming a common connecting root system. It is native to the U.S. and occurs naturally on the lower Appalachian mountain slopes. It has been extensively planted for its nitrogen-fixing qualities and its hard wood. Control Methods: Mechanical: Mowing and burning is only temporarily effective because of the tree's ability to resprout and spread vegetatively. Chemical: Cut-stump treatment with 6.25% glyphosate solution (Roundup/ Rodeo) Cut-stump or basal bark spray treatment around the stem with 25% triclopyr solution (Garlon). Foliar spray in single species stands with glyphosate (Roundup/ Rodeo) or clopyralid (Transline) **Since Black Locust spreads though runners, any cutting of the root material by pulling or digging will actual aid in the propagation and spread of the plant. Cut-stump herbicide treatment is recommended. 7

8 Buckthorn Common buckthorn (Rhamnus cathartica) was first brought to Minnesota from Europe in the mid-1800s as a very popular hedging material. Shortly after its introduction here, it was found to be quite invasive in natural areas. The nursery industry stopped selling it in the 1930s, but many buckthorn hedges may still be found in older neighborhoods throughout Minnesota. Glossy buckthorn (Frangula alnus), also from Europe, has been sold by the nursery trade in two different forms. The cultivar Columnaris has a narrow and tall form; the cultivar Aspenifolia spreads up to 10 feet and has narrow leaves that give it a ferny texture. This buckthorn aggressively invades wetlands including acidic bogs, fens and sedge meadows. Ecological Threat Out-competes native plants for nutrients, light, and moisture Degrades wildlife habitat Threatens the future of forests, wetlands, prairies, and other Buckthorn is one of the natural habitats most invasive species Contributes to erosion by shading out other plants that grow found in Minnesota. on the forest floor Serves as host to other pests, such as crown rust fungus and soybean aphid Forms an impenetrable layer of vegetation Lacks "natural controls" like insects or disease that would curb its growth Regulations European or common buckthorn and glossy or alder buckthorn are listed as restricted noxious weeds in Minnesota. It is illegal to import, sell, or transport buckthorn in Minnesota. Buckthorn leafs out early and retains leaves late into the fall creating dense shade that helps it to out-compete many native plants. 8

9 Buckthorn cont. Controlling seedlings or small buckthorn plants Mechanical Control: If less than 3/8 inch in diameter, remove by hand. Small seedlings can be pulled and will not re-sprout. If greater than 3/8 inch, use a hand tool that pulls the shrub out, such as a Weed Wrench. Limit soil disturbance as much as possible. Soil disturbance aids in propagation of new seeds dormant in the soil. Chemical Control: Spray foliage of short buckthorn or seedlings with a herbicide. Glyphosate (Roundup/ Rodeo) will kill all actively growing vegetation on which it is sprayed. Triclopyr (Garlon) will kill broadleaf plants and will not harm grasses when applied properly. Controlling large buckthorn Buckthorn plants that are two inches in diameter or larger, are best controlled by cutting the stem at the soil surface and then treating the stump to prevent re-sprouting. This can be effectively done with hand tools, chainsaws or brush cutters. Stumps should be treated immediately after cutting (within 2 hours) with a herbicide containing triclopyr (Garlon) or glyphosate (Roundup) to prevent re-sprouting. The best time to cut and chemically treat the stumps is in late summer and throughout the fall. Herbicides can be applied to cut stumps with a low volume sprayer. In cases where more than a few plants are treated, add an indicator dye (available where pesticides are sold) to the herbicide to mark cut stumps you have sprayed. For basal stem treatment, a method that applies chemical through the bark, low volume spray applications can be made with Garlon 4 and similar oil-based products. This application method uses triclopyr ester mixed with an oil diluent (i.e. Bark Oil Blue, kerosene or diesel oil) applied directly to the bark of buckthorn from the root collar up about inches. This treatment works best on stems less than 2-3 inches in diameter. An ultra low volume spray wand should be used to minimize herbicide use and reduce the potential for non-target injury. Buckthorn treated in this fashion can be left standing or cut at a later date. Note: Buckthorn seeds in the soil can remain viable for up to five years. Follow-up control of seedlings that emerge after initial control efforts is important on all sites. With no follow-up control, buckthorn will come back. Fire offers a long-term management option in grassland or savanna cover-types. Burning will need to be done every two to three years. If burning is not an option, a follow up treatment of the seedlings (pulling or spraying) is needed. Applying chemicals to cut buckthorn. 9

10 Canada thistle (Cirsium arvense) Appearance: Perennial herbaceous plant, 2-5' tall with slender grooved stems that branch only at the top. It has male and female plants. Leaves: Alternate, smooth, oblong, tapering, and directly attached to the stem, deeply divided, with prickly margins. Flowers: Numerous small purple flowers appear on top of the upper branched stems between June and September. Seeds: Small light brown seeds are tufted for dispersal by the wind. Seeds remain viable in the soil for over 20 years. Roots: Each plant has a fibrous taproot with wide spreading horizontal roots. Each small section of root can form a new plant enabling the plant to spread vegetatively. Ecological Threat: Canada thistle invades natural areas such as prairies, savannas, glades and dunes if some degree of disturbance already exists. It also invades wet areas with fluctuating water levels such as stream banks, sedge meadows and wet prairies. Once it has established itself it spreads quickly replacing native plants, diminishing diversity. It grows in circular patches spreading vegetatively through horizontal roots which can spread 10-12' in one season. It has been declared a noxious weed in 43 states as one of the most tenacious agricultural weeds. Canada thistle is on the MDA Prohibited noxious weeds list in Minnesota. Control Methods: Mechanical: Repeated pulling and mowing weaken roots. Mow when flower buds are just to open. Mow at one month intervals over several growing seasons. Late spring burns in May/June are most detrimental, but also stimulate seed germination; burn consecutively for 3 years. Chemical: Spot application with 2, 4-D or with selective herbicide clopyralid (Transline) Biological: Stem weevil, bud weevil and stem gall fly. **Canada thistle can recover from almost any stress induced by control attempts, because of root nutrient stores. Therefore, returning infested land to a productive state occurs only over time. Combine mechanical and chemical control methods. 10

11 Crown vetch (Coronilla varia) Appearance: Perennial herbaceous plant, growing 2-6' long stems with a reclining and trailing growth pattern. In winter and early spring crown vetch can be easily recognized as brown unsightly patches. Leaves: Pinnately (feather-like) compound, (leaflets on both sides of a common stalk) with pairs of oblong leaflets. Flowers: Clustered in flat-topped umbels ranging from pink, lavender to white on extended stalks which grow from the leaf axils; blooming from May through August. Seeds: Slender seeds are contained in finger-like pods; they remain viable in the soil for 15 years. Roots: Spread vegetatively with horizontal stems growing below the soil surface, called rhizomes, forming roots and producing new plants. They can grow up to 10' long, contributing to extensive vegetative spread. Ecological Threat: It is now a serious invader of prairies and dunes. It is found in disturbed remnant prairies and woodland edges, gravel bars along streams, as well as agricultural land and roadsides. It prefers open and sunny areas. It was introduced from Europe and southeast Asia during the 1950s as groundcover, bank and slope stabilizer along roads and waterways, and as green fertilizer crop, and it is still sold commercially. Control Methods: Mechanical: Hand pulling of mature plants can be effective when controlling small infestations, but all pieces of stem, roots, and rhizomes must be removed to prevent resprouting. Prescribed burning in late spring for several successive years Mowing in June and late August for several successive years Chemical: Spot spraying affected areas after plants re-green from a burn or mowing, with clopyralid + surfactant + dye (Transline), glyphosate (Roundup), triclopyr (Garlon), or 2,4-D. **Mowing at a frequency of less than once per year proves only to slow spread. Prescribed burning only effectively kills seedlings or slows spread. Mechanical methods should be used prior to herbicide application to reduce biomass, thus increasing herbicide spray coverage. 11

12 Garlic mustard (Alliaria petiolata) Appearance: Biennial herbaceous plant with weak single stems 12-36" high in its second and flowering year. Only plant of this height blooming white in wooded environments in May. Leaves: Round, scallop-edged, dark green; first year, rosettes of 3 or 4 leaves; second year plants have alternate stem leaves. Leaves and stems smell like onion or garlic when crushed. Flowers: White, small and numerous, with four separate petals. Each plant has one or two flowering stems on second year plants. Seeds: Slender capsules " long, containing a single row of oblong black seeds. Seeds are viable in the soil for 5 years. Roots: White, slender taproot, "S"-shaped at the top. Ecological Threat: Garlic mustard spreads into high quality woodlands upland and floodplain forests, not just into disturbed areas. Invaded sites undergo a decline on native herbaceous cover within 10 years. Garlic mustard alters habitat suitability for native insects and thereby birds and mammals. This European exotic occurs now in 27 midwestern and northeastern states and in Canada. Garlic mustard is on the MDA Prohibited noxious weeds list in Minnesota. Control Methods: Mechanical: Repeated pulling in areas of light infestations Flowering stem cutting at ground level to prevent seed production. Cut when seedpods are present but before seeds mature and scatter. Cut, bag, and remove seed stalks. Prescribed burning if there is enough fuel to carry the flames Chemical: Spot application of 2% glyphosate (Roundup/ Rodeo) in early spring or late fall **Fire can encourage germination of stored seeds and promote growth of emerging garlic mustard seedlings. For this reason, burns must be conducted for three to five consecutive years. Regardless of the control method employed, annual monitoring is necessary for a period of at least five years to ensure that seed stores of garlic mustard have been exhausted. 12

13 Honeysuckle (Lonicera tartarica, L. morrowii, L. x bella) Appearance: Upright deciduous shrubs, 5-12' high. Lonicera x bella is a horticultural hybrid. Older stems have shaggy bark and are often hollow. Leaves: Opposite, simple, oval, and untoothed. L. tartarica has smooth, hairless leaves, L. morrowii has downy leaves. Flowers: Fragrant, tubular, bloom in May and June, white, red, but most often pink. Fruit: Fruits are red or yellow, situated in pairs in the leaf axils. Roots: Roots are fibrous and shallow. Ecological Threat: Exotic honeysuckle replace native forest shrubs and herbaceous plants by their invasive nature and early leaf-out. They shade out herbaceous ground cover and deplete soil moisture. Seeds are readily dispersed by birds. Some research suggests that the plant inhibits the growth of other plants in its vicinity. Introduced to North America as ornamental shrubs and beneficial to wildlife. Commercial propagation continues with many cultivars available from nurseries. Control Methods: Mechanical: Pulling seedlings in small infestations when soil is moist. Prescribed burning will kill seedlings and top kill mature shrubs, repeated burns may be needed to control infestations. Chemical: Cut-stump treatment with 20% glyphosate (Roundup/ Rodeo). Cut-stump or basal bark spray treatment around the stem with triclopyr (Garlon). Foliage spraying with glyphosate (Roundup/ Rodeo), where burning is not possible, prior to leaf out of native species. **Hand pulling is not recommended since disturbed soil is prone to future weed infestations. Cutting coupled with a cut-stump herbicide application proves most effective. Annual prescribed burns are recommended for the first few years following honeysuckle removal. 13

14 Leafy spurge (Euphorbia esula) Appearance: Perennial herbaceous plant, 2-3 1/2' tall, erect branching, smooth stems growing from a deep vertical root. Stems, flowers, and leaves emit a white milky sap when broken. Leaves: Alternate, small, oblong to lance-shaped, on the upper part of stem; scale-like on the lower part of the stem. Flowers: Small, borne by showy yellow-green bracts which open in late May; flowers bloom from June into fall. Umbrella-shaped flower cluster, 7-10, at the top of each stem, single, stemmed flowers grow from leaf axils below. Seeds: Explosive dispersal from a seed capsule up to 15'; high germination rate; seeds remain viable in the soil for 7 years. Roots: Extensive deep root system, vegetative reproduction from crown and root buds. Ecological Threat: Rapidly invades primarily non-cropland disturbed environments, such as roadsides. Is a threat primarily to moist and dry prairies and savannas, quickly displacing native plants. Tolerant of a wide range of habitats, from dry to moist, and sunny to semi-shade. Most aggressive in dry soil conditions where there is less competition from native plants. Native to Europe and Asia it occurs across much of the northern U.S. in the grasslands and savannas of the Great Plains. Leafy spurge is on the MDA Prohibited noxious weeds list in Minnesota. Control Methods: Mechanical & Chemical: Prescribed burning in conjunction with repeated treatment with glyphosate (Roundup/ Rodeo) + 2,4-D (one pint each per acre). Combination herbicide/burn regiment recommended for late fall. Biological Root-boring beetle, four root-mining beetles, shoot-tip gall midge **Multiple combination herbicide / burning regiments are necessary every year for several years, making leafy spurge control an extremely expensive undertaking. If left uncontrolled for a single year, leafy spurge can reinfest rapidly. 14

15 Purple loosestrife (Lythrum salicaria) Purple loosestrife is a wetland plant from Europe and Asia. It was introduced into the east coast of North America in the 1800s. First spreading along roads, canals, and drainage ditches, then later distributed as an ornamental, this exotic plant is in 40 states and all Canadian border provinces. Ecological Threat: Purple loosestrife invades marshes and lakeshores, replacing cattails and other wetland plants. The plant can form dense, impenetrable stands which are unsuitable as cover, food, or nesting sites for a wide range of native wetland animals including ducks, geese, rails, bitterns, muskrats, frogs, toads, and turtles. Many rare and endangered wetland plants and animals are also at risk. Location and dispersal: Currently there are about 2,000 purple loosestrife infestations recorded in 68 of Minnesota's 87 counties. Of those sites, the majority (70%) are lakes, rivers, or wetlands. Inventory totals indicate that Minnesota presently has over 58,000 acres infested with purple loosestrife. Likely means of spread: Seeds escape from gardens and nurseries into wetlands, lakes, and rivers. Once in aquatic systems, seeds are easily spread by moving water and wetland animals. Purple loosestrife infestation in MN. Regulations: Purple loosestrife (Lythrum salicaria, L. virgatum and any combination thereof) is listed as a noxious weed and a prohibited exotic species in Minnesota. It is illegal to possess, plant, transport, or sell purple loosestrife in Minnesota. 15

16 Purple loosestrife cont. Appearance: Stalks: Stalks are square, five or six-sided, woody, as tall as 2 meters (over 6 feet) with several stalks on mature plants. Leaves:. Leaves are downy, with smooth edges. They are usually arranged opposite each other in pairs which alternate down the stalk at 90 degree angles, however, they may appear in groups of three. Flowers: Individual flowers have five or six pink-purple petals surrounding small, yellow centers. Each flower spike is made up of many individual flowers. Seeds: As flowers begin to drop off, capsules containing many tiny seeds appear in their place. Depending on where you live, plants may go to seed as early as late July. Each mature plant can produce up to 2.7 million seeds annually. As tiny as grains of sand, seeds are easily spread by water, wind, wildlife and humans. Germination can occur the following season, but seeds may lay dormant for several years before sprouting. Roots: On mature plants, rootstocks are extensive and can send out up to 30 to 50 shoots, creating a dense web which chokes out other plant life. Purple loosestrife can range from 2 to 7 feet high. Control Methods: Chemical: Herbicide application is most effective mid-summer through early fall (July 1 - September 1). Treat as soon as possible after loosestrife begins to flower to minimize seed production. The disadvantage of treating early in the season is that loosestrife plants are difficult to locate because they are not in flower. Glyphosate herbicides are very effective for killing purple loosestrife. Only aquatic formulations of Glyphosate may be used to control purple loosestrife at aquatic sites (such as Rodeo). Roundup can only be used on upland areas for vegetation control. Glyphosate is nonselective; however, selective application techniques allow it to be used effectively with minimum damage to nontarget plant species. Triclopyr, a broadleaf herbicide, can be effective on loosestrife, when used from late May through September. This herbicide is more selective and will not harm monocot species such as cattails. Renovate is the aquatic formulation of triclopyr that can be used to control loosestrife in Minnesota. Wet about 1/4 to 1/2 of the leaf areas of each plant (a "clump" of loosestrife is an individual plant), taking care to avoid spraying other species. Many plants require only one brief squirt of herbicide. Biological: Purple loosestrife eating insects have been released on more than 800 of the 2000 known purple loosestrife infestations in Minnesota. Two leaf-feeding beetles, one root-boring weevil and one flower-feeding weevil were released in MN in Since then, all four species have been established in the state. 16

17 Reed canary grass (Phalaris arundinacea) Appearance: Perennial coarse cool season grass that grows 2-6' high. It had been especially selected for its vigor, and is one of the first to sprout in spring. Erect hairless stems. Leaf blades: 1 4"-1 3" wide, gradually tapering, up to 10" long. It has a highly transparent ligule (a membrane where blade and sheath meet) which distinguishes it from the native bluejoint grass. Flowers: Densely clustered single florets, green to purple changing to beige over time, blooms May to mid-june. Roots: Reproduces vegetatively through horizontal stems growing below the soil surface, called rhizomes, creating a thick impenetrable mat at or directly below the soil surface. Ecological Threat: Reed canary is a major threat to natural wetlands. It out competes most native species. It presents a major challenge in wetland mitigation efforts. It forms large, single-species stands, with which other species cannot compete. If cut during the growing season a second growth spurt occurs in the fall. Invasion is associated with disturbances, such as ditch building, stream channeling sedimentation and intentional planting. This Eurasian species has been planted throughout the U.S. since the 1800s for forage and erosion control. It is still being planted. Control Methods: Mechanical: Consecutive annual burns late spring, early to mid summer or early to mid fall. Mowing mid-june and October to reduce seed and encourage native species. Frequent cultivation followed by fall seeding Shade, landscape fabric, thick sheet mulch Chemical: Application of glyphosate (Rodeo) in fall **Early spring burning stimulates the production of shoots, and therefore is not recommended. Similarly, the use of heavy equipment for reed canary grass removal causes rapid regrowth from rhizomes and seeds that remain in the soil. Clipping back plants at ground level and covering them with opaque black plastic tarps can reduce but not eliminate populations. Rodeo application, followed in two to three weeks by prescribed burning has proven most effective. The use of fire helps to ensure mortality by killing resprouts and germinants. 17

18 CONTROL METHODS While invasive species rarely can be eradicated, their populations can be controlled and adverse impact minimized via manual, mechanical, biological, and/or chemical means. Control methods used to combat invasive species also impact habitat. Different methods of control must be explored and the method that proves least damaging to the ecosystem must be selected. Control methods are implemented to manage the land for biodiversity, not just for the destruction of invasive species. A. Manual and Mechanical Manual and mechanical techniques such as pulling, cutting, and otherwise damaging plants, may be used to control some invasive plants, particularly if the population is relatively small. These techniques can be extremely specific, minimizing damage to desirable plants and animals, but they are generally labor and time intensive. Treatments must typically be administered several times to prevent the weed from re-establishing, and in the process, laborers and machines may severely trample vegetation and disturb soil, providing prime conditions for re-invasion by the same or other invasive species. Manual and mechanical techniques are generally favored against small infestations and/or where a large pool of volunteer labor is available. They are often used in combination with other techniques, such as herbicide treatment or fire. When using manual and mechanical methods, it is especially important to thoroughly clean and inspect all equipment and clothing before moving it off-site. This will lessen the probability of spreading the weed(s) to the next worksite. Weed Pulling Pulling or uprooting plants can be effective against some shrubs, tree saplings, and herbaceous and floating weeds. Annuals and tap-rooted plants are particularly susceptible to control by hand-pulling. Hand pulling is often the best way to control small infestations or exotics in areas without easy access. The key to effective hand pulling is to remove as much of the root as possible while minimizing soil disturbance. For many species, any root fragments left behind have the potential to re-sprout, and pulling is not effective on plants with rhizomes, deep and/or easily broken roots. Weed wrenches and other tools enable control of large saplings and shrubs that are too big to be pulled by hand. Most weed-pulling tools are designed to grip the weed stem and provide the leverage necessary to pull its roots out. Hand tools such as the weed wrench work best on firm ground as opposed to soft, sandy, or muddy substrates. Weed wrenches are available in four sizes, from the mini, which weighs 5.25 lbs and is capable of pulling weeds with stems up to 1.0 inch in diameter, to the heavy, which weighs 24 lbs and can handle weeds up to a diameter of 2.5 inches. Minimize soil disturbance by pulling out weeds slowly and carefully, and replace soil to disturbed areas where possible. Trampled and disturbed areas can provide optimal germination sites for many weeds. Minimize trampling by limiting the number of people in the site and the amount of time spent there. The advantages of pulling include its small ecological impact, minimal damage to neighboring plants, and low (or no) cost for equipment or supplies. Pulling is extremely labor intensive, however, and is effective only for relatively small areas, even when abundant volunteer labor is available. 18

19 Mowing / Brush-cutting / Chainsawing Mowing and cutting can reduce seed production and restrict weed growth, especially in annuals cut before they flower and set seed. Some species however, re-sprout vigorously when cut, replacing one or a few stems with many that can quickly flower and set seed. Be sure to consider the biology of the weed before cutting. Mowing, cutting, and sawing are often used as primary treatments to remove aboveground biomass, in combination with prescribed burning or herbicide treatments. It is important to collect the cut fragments of species capable of re-sprouting from stem or root segments to prevent them from washing or blowing into uninfested areas. Girdling Girdling is often used to control trees or shrubs that have a single trunk. It involves cutting away a strip of bark several centimeters wide all the way around the trunk. The removed strip must be cut deep enough into the trunk to remove the vascular cambium, or inner bark, the thin layer of living tissue that moves sugars and other carbohydrates between areas of production (leaves), storage (roots), and growing points. This inner cambium layer also produces all new wood and bark. To girdle a tree, cut parallel lines approximately three inches or more apart around the circumference of the tree. The cuts can be made using a knife, ax, or saw, and should be slightly deeper than the cambium. Strike the trunk sharply between the cuts using the back of an ax or other blunt object. The bark should come off in large pieces and prevent the tree from any further growth. It is important not to cut too deeply into the trunk because this could cause the tree to snap and fall in high winds. To determine the depth of the cambium, make two short test cuts and strike the bark between the cuts. After several strikes the bark should come off intact, exposing the cambium and wood (xylem) below. Girdling is effective against pines, some oaks, and some maples. It typically requires less labor than cutting and removal, is inexpensive, and kills only the targeted plant. It also leaves no residue except the standing trunks. In addition, a dead standing tree (snag) can provide valuable wildlife habitat, and if left to decay, allows the nutrients of the tree to be returned to the system, rather than being removed and deposited elsewhere. A few species, notably black locust (Robinia pseudoacacia) should not be girdled because it responds by producing many fast growing root and stem sprouts. Therefore, before girdling, find out if the target species responds by re-sprouting. If so, use another control technique, such as herbicide application or fire. Mulching Mulch is a layer of decaying organic matter that occurs naturally in all forests. It is a nutrient rich, moisture absorbent bed of decaying forest leaves, twigs and branches, teeming with fungal, microbial and insect life. Natural mulch serves as a "nutrient bank," storing nutrients contained in organic matter and slowly making these nutrients available to plants. Mulch forms a necessary link in nutrient cycling vital for our soils. 19

20 Mulching improves nutrient and water retention in the soil, encourages favorable soil microbial activity and worms, and suppresses weed growth. Mulching can be used to control invasives in relatively small areas, but may stunt or stop growth of desirable native species. Mulching cannot control some perennial weeds because their extensive food reserves allow them to continue to grow up through the mulch. To mulch, cover the ground and/or seedlings with organic matter such as hay, grass clippings, or wood chips. Newspaper clippings can also be used. This prevents weed seeds and seedlings from receiving sunlight necessary to survive and grow. When properly executed, mulching can significantly improve the well-being of native plants and reduce maintenance as compared to bare soil culture. Mulched plants have better vigor and, consequently have improved resistance to pests and diseases. Sheet Mulching Sheet mulching is a related technique for controlling invasive species and improving soil and plant health. Sheet mulch is put down in layers to mimic natural forest mulch. To prepare the site for sheet mulching, knock down tall weeds and woody plants manually or with a brush cutter. Then proceed to lay down the following four layers: 1) Concentrated Compost: Encourage microbial activity by adding enriched nitrogen-rich compost, manure, worm castings, etc. at the rate of about 50 lbs/100 square feet. If the soil is acidic, add a layer of lime or crushed coral and soak with water to disperse these additions. 2) Weed Barrier: Put down an organic weed barrier to prevent the germination and eventual emergence of weeds through the mulch. Underneath this weed barrier grasses and weeds die and are processed by earthworms that turn and aerate the soil. Of the four sheet mulch layers, the weed barrier has no natural counterpart on the forest floor. In the forest, weeds do not sprout because there is "no room for them," due to a lack of space above and below the ground, and a lack of light. By planting an area properly, there will eventually be no room for weeds. The weed barrier is needed only for establishment of the mulch, and disappears with time. If the area is planted appropriately, weeds will not emerge after the decomposition of the weed barrier. The weed barrier can be composed of 4-6 sheets of cardboard. Overlap the pieces of material to completely cover the ground without any breaks, except where there are plants you want to save. Around these leave a generous opening for air circulation around the root crown. 3) Compost Layer: Located on top of the weed barrier, the compost layer must be weed seed free. Well conditioned compost, grass clippings, seaweed and leaves are ideal materials to spread over the weed barrier to form a dense layer about 3 inches deep. 20

21 4) Top Layer: The top layer must also be weed seed free. Good materials for this include leaves, twigs and small branches, straw, sawdust, and bark. Wood chips are most commonly used due to their high effectiveness and availability. This layer should be about 3-5 inches deep. The top layer will slowly decompose into lower layers, and therefore must be replaced periodically. Layer 2 (cardboard weed barrier) and layer 4 (wood chip top layer) are the most critical for inhibiting growth of invasive species. At minimum, these two layers must be established and maintained. Layer 1 (concentrated compost) and layer 3 (compost layer) aid in soil rehabilitation, which is a better long term solution. All layers should be employed when time and resources permit. Eventually, maintenance tasks such as watering, fertilization and weeding will be reduced. The overall maintenance burden in mulched conditions, when properly executed, is far less than in conventional systems. B. Biological Control When a plant from one continent is introduced to another, it usually leaves behind the natural enemies that help prevent population explosions where it normally grows. The purpose of biological control is to reunite a plant with its natural enemies. Biological control (biocontrol for short) is the use of animals, fungi, or other microbes to feed upon, parasitize or otherwise interfere with a targeted pest species. Complete eradication is unlikely; the goal of biocontrol is to reduce numbers of the target plant to lessen its ability to displace native vegetation. Successful biocontrol programs usually significantly reduce the abundance of the pest. However, in some cases, they simply prevent the damage caused by the pest (e.g. by preventing it from feeding on valued crops) without reducing pest abundance. There are several general approaches to using biocontrol agents: Classical biocontrol: targets a non-native pest with one or more species of biocontrol agents from the pest s native range. This is the most common approach for plant pests. New Association or Neoclassical biocontrol: targets native pests with non-native biological control agents Conservation, Augmentation, and Inundation: maintains or increases the abundance and impact of biocontrol agents that are already present, and in many cases native to the area. Conservation and augmentation approaches show great promise for enhancing the impacts of classical biocontrol. Biocontrol is often viewed as a progressive and environmentally friendly way to control pest organisms because it leaves behind no chemical residues that might have harmful impacts on humans or other organisms, and when successful, it can provide essentially permanent, widespread control with a very favorable cost-benefit ratio. However, some biocontrol programs have resulted in significant, irreversible harm to untargeted (non-pest) organisms and to ecological processes. Therefore, before releasing a biocontrol agent, it is important to balance its potential to benefit conservation targets and management goals against its potential to cause harm. 21

22 C. Prescribed Burns Fire can encourage the germination of some plants, including a number of rare and endangered species. Conversely, fire can also sharply reduce the abundance of some species. The weather, topography, and fuel type will determine the temperature and intensity of the prescribed burn, and this along with the timing of the treatment, will determine how the burn impacts the vegetation and the abundance of particular species. The most effective fires for controlling invasive plant species are typically those administered just before flower or seed set, or at the young seedling/sapling stage. In some cases, prescribed burns can unexpectedly promote an invasive. These prescriptions must be modified or other management actions taken to undo or reverse the promotion of the invader. For example, repeated burns may be necessary to effectively control weedy plants and/or herbicide treatments may be required to kill the flush of seedlings that germinate following a burn. Resprouts or seedlings that are 1 to 3 months old are often especially sensitive to herbicides. The most effective prescribed burn plans are those that mimic natural fire regimes (which may have been disrupted by land use changes, urban development, fire breaks, or fire suppression practices). Many prescribed burn programs are designed to reduce the abundance of certain native woody species that spread into unburned pinelands, savannas, bogs, prairies, and other grasslands. Spot-burning invasive weeds with a propane torch can be cheaper and easier than implementing a prescribed fire (permits are still required), but is only effective when the infestation is small. Spot-burning can be used to burn individual plants, groups of plants in a small area, or to ignite brush piles. Propane torches can be used in areas where there is little or no fine fuel to carry a prescribed burn, and can also be used to kill plants when conditions are wet. D. Chemical Herbicide application is often used for large scale invasive species control. It is best to select compounds that are effective against the weed, not likely to drift, leach to groundwater or wash into streams, nontoxic to people and other organisms, not persistent in the environment, and are easy to apply. In some circumstances, a single application of a more toxic or persistent chemical that kills the weed, however, may be preferable to a less persistent, less toxic compound that must be applied repeatedly. Strive to do the job with the smallest total negative impact to the environment. Foliar Application: In foliar application, herbicide is sprayed on plant leaves, stems, or shoots. Foliar herbicide applications are most effective when the vegetation to be controlled is between two and six feet in height. All foliar treatments should be made after full leaf expansion in the spring and before fall colors are visible. Foliar applications should be made with a low pressure (20-50 psi) backpack sprayer. Apply herbicide with a backpack or similar hand-operated pump sprayer equipped with a flat spray tip or adjustable cone nozzle. Apply herbicide to the leaves and stems of target plants using a consistent back and forth motion. Herbicide should thoroughly cover foliage, but not to the point of run-off. All recommended herbicides require complete foliar coverage to be effective. Applications made while walking backward will reduce the risk of the herbicide wicking onto the applicator's clothing. Allow herbicide treatments to dry for at least three hours at an air temperature above 60 F to ensure adequate absorption and translocation. In areas that receive significant public use, it may be necessary to close off the treatment area until the herbicide has completely dried. 22

23 Adequate control with foliar applications can be difficult to accomplish since complete coverage of all foliage is essential for control, but over-application (that leads to spray run-off) will reduce effectiveness. Therefore, foliar applications commonly require multiple follow-up treatments before control is accomplished. It is important to control spray drift when making foliar applications. Certain desirable hardwood and crop species are highly sensitive to spray drift and can be inadvertently damaged. Basal Application: Basal bark treatments are effective for controlling woody vines, shrubs, and trees. Treatments can be made any time of year, including the winter months, except when snow or water prevents spraying the basal parts of the stem. Proper plant identification is crucial during the dormant season due to the absence of foliage. Basal application combines the herbicide with penetrant oil (i.e. Garlon 4 and Bark Oil Blue) and applies the mixture directly to the bark of a standing tree (i.e. Buckthorn). For trees that are less than 6-inches in diameter and have smooth bark, this method is frequently successful. However, it is important that the lower 12 to 18 inches of the stem be treated on all sides with the herbicide/oil mixture. Adequate coverage is essential, since treating only one side of the stem will result in controlling only half of the tree. Basal applications can be made any time of the year, but are most effective during the dormant season when leaves are not present. Basal applications will not provide rapid control. Herbicide injury is often not observed for several weeks after treatment and total control may require several months. Additionally, basal treatment is not effective on older trees with thick bark. For older trees, other application techniques should be employed. Cut Stump: This technique is employed after cutting a tree to eliminate, or greatly reduce, resprouts from the cut surface. The herbicide should be applied to the cut surface as quickly as possible, after the sawdust has been removed. If applied immediately, a herbicide/water solution is sufficient. If herbicide treatment is delayed and the cut surface has begun to dry, a herbicide/basal oil mixture must be applied to the top and around the collar of the stump. For stumps greater than 3 inches in diameter, wet the outer edge while avoiding herbicide runoff. Only living tissue in larger trees is around the outer edge. Covering the entire cut surface will require more herbicide, most of which will provide little effect. For smaller stems it is appropriate to cover the entire cut surface. For this procedure, herbicides can be applied using a backpack sprayer, squirt bottle, or paint brush. A tracer dye should be used to ensure treatment of all stumps. 23

24 Instruments for Herbicide Application: Backpack Sprayer: Tanks made of high-tensile, UV-stabilized polyethylene with highimpact strength and chemical resistance. Weighs 9-1/2 lbs. empty. Large 4" opening with strainer for safe fillings. Padded nylon web straps. Adjustable pump handle for left or right hand operation. Diaphragm pump generates a lower pressure (maximum 60 p.s.i.) resulting in larger droplets with less spray drift. Works well with abrasive sprays or wettable powders which may cause wear to piston pumps. Delivers 0.5 GPM at 60 p.s.i. Supplied with two spray nozzles which provide three different spray patterns. Flat spray nozzle is recommended for general area spraying (foliar application). For spot spraying (basal bark treatment), the conical nozzle provides a cone-shaped spray when used with the swirl plate and a pin-stream spray without the swirl plate. Hand Sprayer: Piston Pump Sprayer is ideal for quick and small spray applications Weighs 1 lb. Adjustable nozzle to modify spray (from single stream to spray). Pump builds pressure to determine spray rate. Most practical for cut-stump treatment. Dauber: Permeable, absorbent, material such as a sponge, located on the end of the bar, dispenses herbicide. The sponge remains saturated with herbicide (from the bar) for continual application. Bar length minimizes risk of herbicide contact with the applicator. Most practical for cut-stump treatment 24

25 Herbicides INTRODUCTION Herbicides are chemical compounds that kill plants or inhibit their normal growth. A herbicide in a particular formulation and application can be described as selective or nonselective. Selective herbicides are used to control weeds without damaging crops or other non-target species. Nonselective herbicides are toxic to all plants and are used where complete control of plant growth is required. Contact herbicides kill only the parts of the plant they touch, while systemic herbicides are absorbed by foliage or roots and translocated to other parts of the plant for complete destruction. Preemergence herbicides, mixed into the soil, will kill germinating seeds and small seedlings. Postemergence herbicides either hinder photosynthesis or inhibit growth. HISTORY Early chemical herbicides were inorganic compounds. Herbicides such as ashes, common salts, and bittern have been used in agriculture since ancient times. Observation in 1896 that Bordeaux mixture, a fungicide, also provided control of certain weeds, led to the use of copper sulfate as a selective weed killer to control charlock (wild mustard) in cereals. By 1900, solutions of sulfuric acid, iron sulfate, copper nitrate, and ammonium and potassium salts were known to act as selective herbicides; soon thereafter sodium arsenite solutions became the standard herbicides, and they were used in large quantities until about Other inorganic herbicides include ammonium sulfamate, carbon bisulfide, sodium chlorate, sulfuric acid solutions, and formulations containing borate. Organic herbicides began to be produced in earnest with dinitrophenol compounds in A breakthrough occurred in the 1940s with 2,4-D (2,4-dichlorophenoxyacetic acid), a compound similar to plant hormones, which is a highly selective systemic herbicide when used in very small quantities. 2,4-D was quickly adopted to control broad-leaved weeds in corn, sorghum, small grains, and grass pastures, as well as in lawns and other ornamental turf. The phenoxyaliphatic acids and their derivatives, another major group of organic herbicides, succeeded because of their selectivity and ease of translocation. Other groups of organic herbicides include organic arsenicals, substituted amides and ureas, nitrogen heterocyclic acids, phenol derivatives, triazines, and sulfonylureas. In the 1960s and 1970s, a combination of 2,4-D and 2,4,5-T was widely used in Vietnam as a defoliant under the name Agent Orange. As a result of questions concerning the possible health effects of the use of Agent Orange, heightened awareness of possible ecological and health dangers attributable to herbicides has resulted in reevaluation of many compounds and has called indiscriminate use into question. Use of the dioxin-containing 2,4,5-T was prohibited in the United States in In 1975, Mexico, at the urging of the United States government, began spraying fields of marijuana with paraquat, which both eliminated the crop and raised fears of toxic side effects in marijuana users. 25

26 REGULATION In the United States, the EPA regulates pesticides. During the registration process, a label is created which contains directions for the proper use of the material. Based on acute toxicity, pesticides are assigned to a Toxicity Class. Pesticides considered too hazardous for sale to the general public are designated restricted use pesticides. Only certified applicators, who have passed an exam, may purchase or supervise the application of restricted use pesticides. * As non-commercial applicators, Corpsmembers only need licensing if applying restricted use herbicides. None of the herbicides MCC applies are restricted use. The Federal Insecticide, Fungicide, and Rodenticide Act of 1972 (FIFRA) set up the current system of pesticide regulations. It was amended somewhat by the Food Quality Protection Act of Its purpose is to make pesticide manufacture, distribution and use as safe as possible. The most important points for users to understand are these: it is a violation to apply any pesticide in a manner not in accordance with the label for that pesticide, and it is a crime to do so intentionally. HERBICIDE LABEL INFORMATION All US registered pesticides must have a label approved by the EPA. The label contains product information, including relative toxicity, potential hazard to humans and the environment, directions for use, and first aid treatment in case of exposure. Each section of the sample label below is detailed on the following page. 26