Kentucky’s Top 10 Worst Plant Threats

Chemical Control of Plants

• What is needed:– Carrier (water or oil)– Herbicide– Surfactants (optional)

Types of Herbicides

Glyphosate

• Inhibits aromatic amino acid synthesis

• Brands– Accord (DowAgro)– Roundup (Monsanto)

• not registered for forestry)– Rodeo (Monsanto)

• aquatic label– Various generics

Types of Herbicides

Imazapyr

• Inhibits branched amino acid synthesis• Does not kill conifers

– Release pine from hardwoods

• Brands– Arsenal AC (BASF)

• Amine formulation – Chopper (BASF)

• Ester formulation

Types of Herbicides

Triclopyr• Behaves like auxin (IAA)• Over stimulates cell metabolism• Brands

– Garlon 4 (DowAgro) • Ester formulation for foliar and basal bark applications• Effective on actively growing brush by penetrating the bark and

entering the cambium layer. Also effective as a late-season application

– Garlon 3A (DowAgro)• Amine formulation for foliar, cut surface and tree injection applications. • Foliar applications are most effective during the period of active growth. • Tree injections and cut surface treatments can be applied year-round.

Types of Herbicides

• Hexazinone (DuPont)– Soil-active herbicide controls trees, brush, weeds, and

grasses by inhibiting photosynthesis– Brands

• Velpar L – Liquid• Velpar ULW – Granule• Oustar (+ sulfometuron) – Soluble granules

Types of Herbicides

• Metsulfuron (DuPont)– Escort XP

• Dispersible granule, postemergent herbicide

• Mixes in water for spray application and controls many annual and perennial weeds and woody plants in non-crop areas and conifer plantations.

• Best results are generally obtained when applied to foliage after emergence or dormancy break because

• Escort XP is absorbed primarily through the foliage of plants and by the roots to a lesser degree.

Types of Herbicides

• Sulfometuron - DuPontOust XP

– Oust Extra is a dispersible granule herbicide that is mixed in water and applied as a spray or impregnated on dry, bulk fertilizer.

– When applied as a spray, it is absorbed by both the roots and foliage of plants, rapidly inhibiting the growth of susceptible weeds.

– When applied on dry fertilizer, Oust Extra is absorbed primarily by the roots.

– For best results, apply before or during the early stages of weed growth before weeds develop an established root system.

Types of Herbicides

• Clopyralid

Transline (DowAgro)– For selective, postemergence control of

broadleaf weeds– Effective only on composites and legume

Types of Herbicides

• Picloram– Tordon (Dow-Agro)– Pathway RTU (Dow-Agro)

• Ready-to-use herbicide is effective in cut surface applications

• Premixed with dye

• Use undiluted with tree injectors or in the frill girdle treatment using an axe.

• Active ingredients are 5.4% picloram and 20.9% 2, 4 D-Amine.

Amur Honeysuckle

• Amur honeysuckle (Lonicera maackii) is a tardily deciduous, upright, arching shrub to small tree.

• Forms dense thickets in open forests, forest edges, old fields, and roadsides

• Forms a dense shrub layer that crowds out native plants and regeneration

• Depletes soil moisture and nutrients• Berries do not provide the fat and

nutrient rich food that native species provide– Especially needed by birds for long flights

Amur Honeysuckle

• Identified by arching habit, opposite branching and dark green leaves, red to orange glossy berries paired in leaf axils

• Bark flaky and older branches hollow (native honeysuckles are solid)

• States reporting infestations

Amur Honeysuckle

• Hand pulling or mechanical removal can be used on small plants or light infestations

• For seedlings and small plants; systematic herbicide like glyphosate at 2% solution can be applied to the foliage by spray or sponge

• Well established stands should be cut and the stump sprayed or painted with a 20% solution of glyphosate.

• Prescribed burning can be useful in open habitats.– Treatment should be used before seed dispersal (late summer,

early autumn) to prevent reinvasion.

Kudzu

• Kudzu (Pueraria montana) is a twining, trailing, mat-forming, ropelike, woody leguminous vine.

• Occurs in old infestations, along right-of-ways, and stream banks

• Forms dense mats over the ground, debris, shrubs, and mature trees.

• Little spread by seed, usually spreads slowly by runners

• Completely covers, kills by denying light penetration, and replaces existing vegetation.

Kudzu

• Identified by alternate, pinnately compound, three-leaflet leaves

• Stems yellow green with dense, erect golden hairs, aging to ropelike, gray, and hairless

• Flowers lavender to wine-colored with yellow centers

• Flattened, tan, fuzzy, legume seed pods

• The most severe infestations occur in the piedmont regions of Alabama, Mississippi, and Georgia.

Kudzu

• Very difficult to control– Estimated cost up to $200 per acre for 5

years

• Thoroughly wet all leaves the 3% solution of Tordon 101 or 2% Tordon K– July to October for successive years

when regrowth appears– Spray climbing vines as high as possible

or cut those that cannot be controlled– Prescribed burning in the spring can clear

debris, sever climbing vines, and reveal hazards, making summer applications easier.

Winged Burning Bush (Euonymus alata)

• Imported from Asia as a ornamental shrub

• Shade tolerant, spreads by root suckers and animal dispersed seeds

• Widely planted as an ornamental and along highways

• Threatens forests, prairies, and coastal scrublands where it can form dense thickets and displace native woody and herbaceous vegetation.

Winged Burning Bush

• Multiple stemmed and many branched, bushy shrub to 12 feet in height

• Opposite leaves, dark green above, light green beneath– Fall color bright red

• Four corky wings along young lime green branches

• Seeds dangling pair or single reddish capsules in leaf axil, splitting in fall to reveal orange flesh covered seed.

• Found throughout much of the northeastern United States

Winged Burning Bush

• Thoroughly wet all leaves with Arsenal AC or Vanquish as a 1% solution

• Stems too tall for foliar spray– Apply garlon 4 as 20%

solution in basal oil, diesel fuel, or kerosene with a penetrant as basal spray on young bark

– Cut large stems and treat stumps with 10% solution of Arsenal AC or 20% solution glyphosate herbicide

• Seedlings can be pulled by hand in small infestations

Garlic Mustard (Alliaria petiolata)

• Introduced from europe in the 1800’s for culinary and medicinal uses

• Doesn’t require disturbance to enter forested areas, shade tolerant

• Grows quickly in early spring and late fall, when other species are often dormant

• Obligate biennial, first year seedling “rosette stage” stays green through winter

• Not valuable for animal browse• Overruns and eliminates many

native plants and wildflowers, also allelopathic

Garlic Mustard

• Forb with one to several erect, light green stems from the same rootstock– Hairless above and hairy

below

• Basal rosette of kidney-shaped leaves (1st year), alternate heart-shaped to triangular leaves (2nd year)– Garlic odor when crushed

• Terminal clusters of small white flowers

• States reporting garlic mustard infestation

1st year

2nd year

Garlic Mustard

• Both generations can be controlled by thoroughly wetting all leaves with a 2% glyphosate herbicide solution.– Include surfactant only if plants are not near

surface waters

• When herbicides cannot be used– Hand pull plants before seed formation– Repeated annual prescribed burns in fall or

early spring– Burning individual plants with propane

torches has shown some success

Multiflora Rose (Rosa multiflora)

• Introduced from Asia as ornamental, live-stock containment, wildlife habitat, and living fences

• Widely planted and spreads along right-of-ways, road sides, old fields, and forest margins, sometimes climbing trees

• Colonize by prolific root sprouting, stems that root, and animal dispersed seed

• Extremely prolific and forms impenetrable thickets that exclude native plant species

Multiflora Rose

• Erect climbing, arching, or trailing shrub

• Stems long arching or climbing, recurved thorns

• Leaves alternate, pinnately compound with 3 to 9 leaflets– Leafstalk often bristled with

toothed hairs

• Flowers white with 5 petals

• States reporting infestation

Multiflora Rose

• Cutting or mowing 3 to 6 times per growing season for 2 to 4 years is effective

• Wet leaves with a 1% solution of Arsenal AC (April to June) or use an Escort-water mixture at 1 ounce herbicide per acre (April to October).– 4% glyphosate solution from May to

October is less effective but has no soil activity to damage surrounding plants

• Stems too tall for foliar spray– Apply garlon 4 20% solution in basal oil,

diesel fuel, or kerosene to young bark as basal spray

– Cut stems and treat stumps with Arsenal AC as 10% solution or glyphosate as 20%

Oriental Bittersweet (Celastrus orbiculatus)

• Introduced from Asia as a showy, ornamental vine

• Shade tolerant but most infestations located in forest openings, margins, roadsides, and fields

• Colonizes by aggressive vine growth, bird and animal dispersed seeds

• Shades, suppresses, and kills native vegetation

• Vines seriously damage vegetation by constricting and girdling stems

• Threat to the native and rare American bittersweet (Celastrus scandens) due to hybridization and genetic identity loss

Oriental Bittersweet

• Deciduous, twining, and climbing vine to 60 feet in tree crowns

• Stems olive drab with raised, whitish, corky dots becoming tan to gray

• Leaves alternate and variable, bluntly toothed– Dark green becoming bright

yellow in late summer to fall• Conspicuous fruit; yellow

orange to tan, splitting in winter to reveal fleshy scarlet inner sections, persistent through winter– American bittersweet has only

terminal flowers and fruit

• States reporting

Oriental Bittersweet

• Juvenile plants or those in sensitive areas can be hand or mechanically pulled

• From July to October wet leaves with a 3% mix of Garlon 4, Garlon 3A, or glyphosate.

• For stems too tall:– Garlon 4 as 20% solution in basal oil, diesel

fuel, or kerosene to lower 16 inches of stems– Cut stems and treat cut surfaces with Garlon

4 or glyphosate as a 25% solution

Japanese Knotweed (Fallopia japonica)

• Introduced from Asia in the 1800’s• Invades high light, disturbed areas

– Roadsides, ditches, wetlands, right-of-ways, streambanks, etc.

• Associated with soil disturbances• Rarely found in low light areas such as

forest understories• Dense patches emerge early in the

growing season, crowding out native plants

• Infestations near stream banks increase susceptibility to erosion

• Of little value to wildlife• Seeds wind and water dispersed

Japanese Knotweed

• Dense growing, semi-woody shrub to 10 feet

• Hollow, simply branched stems are smooth and shiny with enlarged nodes

• Leaves are alternate and variable, usually triangle shaped with pointed tip and rounded base

• Flowers greenish-white and minute, seeds small dry achene

• Recognized by extremely dense growth form, often monocultural thickets

• Above ground portions die back in winter

• Particularly abundant in the eastern U.S. and coastal Washington and Oregon

Japanese Knotweed

• Treat foliage with herbicides in mixture with water and surfactant– 2% solution Garlon 4, Garlon 3A, or glyphosate

herbicide– Ideal time to spray when surrounding vegetation has

become dormant (Oct. to Nov.) to avoid damage to non-target species

– If mixed with non-target plants, cut stems 5 cm above ground and treat with 25% solution of above herbicides

• Subsequent foliar applications may be necessary to control new seedlings and resprouts

Purple Loosestrife (Lythrum salicaria)

• Perennial herb introduced from Europe and Asia

• Invades natural and disturbed wetland habitats; wet meadows, marshes, stream and river banks, pond margins, reservoirs, and ditches

• Forms dense homogenous stands– Restricts native plants, including species of

endangered orchids– Crowds out valuable native wildlife food plants,

reduces habitat for waterfowl• Decompose quickly in the fall, causing

nutrient flush and alteration of wetland function

• Reproduces through high volumes of seed and vegetatively through underground stems

Purple Loosestrife

• According to U.S. Fish and Wildlife, occurs in every state except for Florida

• Tall (4 to 10 feet), erect herb with opposite or whorled leaves

• Usually covered with a downy pubescence• Showy display of magenta-colored flower spikes

throughout much of the summer• 30 to 50 stems from a single rootstock

Purple Loosestrife

• Small infestations may be pulled by hand, preferably before seed set

• For older plants spot treatment with glyphosate based herbicide (Roundup for uplands, Rodeo for wetlands)

• Biological control likely candidate for control of large infestations– 3 species of insect from Europe have been approved for use by

the U.S. department of Agriculture• Root-mining weevil (Hylobius transversovittatus), and two leaf-

feeding beetles (Galerucella calmariensis and Galerucella pusilla)• Occasionally feed on native vegetation, but impact on non-target

species is considered low

Hylobius transversovittatusand rootstock damage

Chinese Silvergrass (Miscanthus sinensis)

• Ornamental perennial grass introduced from eastern Asia

• Infests roadsides, forest margins, and adjacent disturbed sites, especially after burning

• Shade tolerant• Highly flammable and fire

hazard• Crowds out native plant species• Seed viability spotty, new

cultivars assumed to be mostly sterile

Chinese Silvergrass

• Tall, densely bunched, 5 to 10 feet in height

• Many loosely plumed panicles in late summer, turning silvery to pinkish in fall

• Dried grass standing with some seed heads during winter

• Blades green to variegated with whitish collars

• Tufted hairs at throat, sheath margins, and ligule, but otherwise hairless

• States with suspected infestations

Chinese Silvergrass

• Thoroughly wet all leaves with herbicides in water with a surfactant– Arsenal AC as a 1% solution– Glyphosate based herbicide as a 4% solution if non-target plants

are an issue– September or October with multiple applications to regrowth

• Manual removal before silvergrass goes to seed can be effective if repeated

Japanese Stilt Grass (Microstegium vimineum)

• Introduced from Asia, sometimes called Nepalese browntop

• Flourishes on alluvial floodplains and streamsides, colonizes flood scoured banks, forest edges, roadsides, damp fields, swamps, lawns, and ditches

• Very shade tolerant• Prolific seeder, remain viable in soil

up to 5 years, spreads by hitchhiking on shoes and clothing

• Little wildlife food value– Replaces valuable native food sources– Wildlife continue to feed on native

species while avoiding stilt grass, helping it colonize

Japanese Stilt Grass

• Sprawling annual grass• Flat short leaf blades with off-

center veins• Stem branching near the base

and rooting at nodes to form dense infestations

• Throat collar hairy, ligule membranous with hairy margin

• Dried whitish-tan grass remains standing in winter

• States reporting infestations

Japanese Stilt Grass

• Manual removal results in disturbed soils and aids germination of more stilt grass– Mowing or pulling just before seed set can

prevent seed buildup– Herbicides can be used on resulting seedlings

• Apply glyphosate as a 2% solution in late summer– Apply Vantage (see label) for situations that

require more selective control and less impact on non-target plants