Landscape Weed Control

Landscape Weed Control Dennis Morgeson

Agent For Horticulture Washington County

What is a weed? + Plant out of place + Plants causing economic loss + Non-native plant (Privet, Ligustrum spp.) + Plants whose virtues have not been discovered

Chinese Privet

Kudzu

Why Control? + Plant competition + Prevent economic loss

+ Hosts for insects and diseases + Maintain landscape beauty

Reasons Weeds Survive + Hard seed coat, deep burial, germination inhibitors, prolific seed production + Persistent vegetative structures: Bulbs, tubers, rhizomes, stolon's, and corms.

Know The Weeds Life Cycle + Annual: Completes growth cycle in a single growing season (crabgrass). + Perennial: A plant that can persist more than two years, and reproduce through roots or seeds (clover). + Biennial: A plant that normally requires two growing seasons to complete its life cycle, flowering and fruiting in its second year (wild carrot).

Seed Germination Factors + Oxygen + Light + Temperature + Water

+ Scarification (physical removal of the seed coat)

So you let just one weed go to seed?

Plant/Seed

• Pigweed • Lambsquarters • Crabgrass • Annual Bluegrass

>200,000 >30,000 53,000 2,000

Weeds can be a problem all 12 months of the year!

Ornamental Weed Control Options + Hand-removal, hoeing + Mulches

+ Landscape fabrics + Herbicides

Number One Question + How do I get rid of these weeds??!

Fabric Mulches + Plastic fabric thickness affects the degree of weed suppression.

+ Clear and colored plastics that allow light penetration produce high temperatures in the upper surface. + This build up of heat, solarization, kills germinating seeds.

Fabric Mulches + Expensive + Very good option for homeowners

+ Use high quality + Properly mulch

Organic Mulches + Straw, wood chips, pine straw, sawdust, newsprint, and other organic materials + These mulches also shade and physically hinder germinating seedlings

Organic Mulches + Coarse texture better than fine + Texture more important than type + 2 to 4 inch depth + Renew as needed + Nothing is permanent!

Mulches + Advantages-Controls most weeds. Good use of waste materials. Conserves water. + Disadvantages-Expensive?

Handling is often a pain.

Hand Pulling and Hoeing + Still used for weed control! + Best control with small weeds. + You need to understand how the weed develops…Annual, Perennial, Biennial…..

Hand Weed Control + Advantages-Keeps you in shape! Environmentally friendly. Controls most seeds inexpensively if you do it yourself. + Disadvantages-Repetition is a must. It can stimulate germination of other weeds. Must be timely.

Tillage + Controls weeds that have emerged. + Incorporates fertilizers, lime, and organic material. + Prepares seed or plant beds.

Tillage + Advantages-Controls most weeds quick and easily. + Disadvantages-Can be expensive. Doesn’t work in a perennial plant situation on a larger scale.

Herbicides + Annual grass control is available for pre and postemergence. + Pre and post broadleaf weed control is available.

+ Spot weed control is available as well. + Vines and woody plants can be difficult to control.

Herbicide Classification + Selective: Kills some plant species, but does not damage others (2,4-D) + Nonselective: Generally kills all plant species (glyphosate)

Before You Use Herbicide + Identify weed. + Read and UNDERSTAND the label . + Follow the directions carefully. + Use only the recommended amount! + Do not use on desirable plants not listed on label.

Ornamental Preemergence Herbicides + Primarily dinitroanilines Treflan, Surflan, Pendulum, Endurance, XL, Team

+ Preen + Preen-N-Green + Snapshot - trifluralin + isoxaben

Ornamental Preemergence Herbicides + + + + + +

Products labeled for various species Irrigate-in if possible (1/2 inch) within 7 days Do not apply to wet foliage Match weeds to specific products Use fall + spring applications Rotate products if possible

Postemergent Herbicides + Vantage (sethoxydim) + Grass-B-Gon (fluazifop-P) + Roundup (glyphosate) + Finale (glufosinate) + Sharpshooter (Potassium salts of fatty acids)

Selective POST Grass Control Herbicides + Sethoxydim-Vantage, HiYield Poast, Grass Beater

+ Fluazifop-Dexol Grassout, Greenlight Bermudagrass Killer, Ortho Grass-BGone (reseeding restriction of two months)

Ornamental POST Grass Control +

Use on any non-grass ornamental Trees, woodies, annuals, perennials Includes liriope, hosta, iris, daylily Don’t spray open blooms

No “nutgrass” control Avoid applications on “scorchy-hot”, humid days

Integrated Weed Management + Integrating preventive, mechanical (mulches, fabrics), cultural and chemical methods is usually the most effective method of managing weeds in ornamentals.

Common Weeds Of Kentucky Life Cycle: Summer Annual Description: A member of the pigweed family, Palmer amaranth is a troublesome summer annual. The eggshaped leaves are arranged alternately along the stem.

The petiole is as long as (or longer) than the leaf itself. Some of the leaves have a V-shaped "watermark", which is white in color. Not all Palmer amaranths will have the watermark. Another variable identification characteristic is the presence of a single hair in the tip of the leaf notch. As the plants mature, the female plants will have a very long terminal seed head.

Common Weeds Of Kentucky Other Names: Pigweed Life Cycle: Summer annual Description: Spiny amaranth is the most common of the pigweeds found in Kentucky's pastures. It can be distinguished from other pigweeds by the pair of spines at the base of the leaf petiole and the central stem.

Common Weeds Of Kentucky Pigweeds (Amaranthus spp.) are native annual plants that are associated with disturbed sites. Leaves are simple and oval- to lance-shaped with an alternate leaf arrangement. Pigweeds germinate readily from late spring through early autumn, produce numerous seeds, and grow quickly. Seeds of weedy species are small and black. Plants have a primary taproot.

Management: •Cultivate when weeds are less than 4 inches tall; cultivation is not effective with larger plants.

•Apply pre-emergent herbicides and spot spray with postemergent herbicides; however, some pigweed populations have herbicide resistance. Herbicide-resistant populations should be confirmed by a county Extension agent or the Weed Science Society of America.

Common Weeds Of Kentucky Other Names: White Aster, Heath Aster, White Prairie Aster, Life Cycle: Perennial Description: This is a perennial plant which can grow to as much as 5 feet tall. The basal leaves are lanceolate and the upper leaves are linear. The stems are erect and the plant produces abundant flowers (white petals with yellow centers) from August through November. White heath aster is mainly a weed of pastures, forages and noncrop areas.

Common Weeds OF Kentucky Other Names: Cockspur grass, Japanese millet Description: Barnyardgrass is an erect summer annual.

It is found in fields, pastures, wet ditches and waste sites. The stems are erect and often bent at the nodes.

The leaves have no ligule.

Life Cycle: Annual

Common Weeds Of Kentucky Field Bindweed Life Cycle: Perennial Description: A climbing vine with white trumpet-shaped flowers. The leaves are triangular in shape. The base of the leaf is lobed and points outward.

Common Weeds Of Kentucky Johnsongrass (Sorghum halepense) is an aggressive perennial common in agronomic fields, along roadways and waterways, and in low lying areas prone to flooding. Mature leaf blades are 5 to 20 inches long with an obvious white rib down the middle. Plants reproduce by seed and perennial rhizomes, making control difficult. Rhizomes are stout compared to other grasses.

Management: •Apply pre-emergent herbicides to help prevent seedling establishment.

•Post-emergent herbicides selective for grasses can be applied when plants are seedlings, but these are less effective once rhizomes have formed.

•Avoid cultivation, which spreads plants.

Common Weeds Of Kentucky Bermudagrass (Cynodon dactylon) is a drought tolerant, warmseason, perennial grass that actively spreads vegetatively by both rhizomes and stolons. It also has the ability to spread by seed. Spikelets on seed heads (typically 3 to 6) are similar to crabgrass and are present from mid-summer through autumn.

While extremely vigorous, bermudagrass is favored by warm weather, so it does not become a problem until later in the season.

Management: •Avoid cultivation, which spreads rhizomes and stolons.

•Chemical control is recommended and must be repeated as plants readily regrow from rhizomes and stolons.

Common Weeds Of Kentucky Goosegrass (Eleusine indica) is a summer annual that grows in a flat rosette; centers appear white. Plants, which have fibrous root systems, are typically found in dry, compacted soils. Plants are frost sensitive. Seed will not germinate until soil temperatures are over 65° F. Management: •Cultivate when plants are young.

•Apply a grass-specific post-emergent herbicide (graminicide).

Common Weeds Of Kentucky Quackgrass (Agropyron repens) is a perennial grass that spreads by seeds and rhizomes. Seed heads are 2- to 7-inch long spikes. Leaves are 4 to 8 inches long and about ¾ inch wide. Narrow projections (auricles) from leaf blades encircle stems. Quackgrass tolerates mowing and usually remains green even when dormant.

Management: •Avoid cultivation, which spreads rhizomes.

•Chemical control is difficult because rhizome buds may remain dormant so they are unaffected by systemic herbicides. Repeat applications are often necessary.

Common Weeds Of Kentucky Canada thistle (Cirsium arvense) is a difficult to manage perennial that spreads by seeds and rhizomes. Leaves are deeply lobed with spines; leaf margins and bases surround stems making stems look spiny as well. Flower heads are usually purple to pink. Root systems may extend more than 10 feet deep.

Management: •Avoid cultivation and spread.

•Cut or mow plants to help reduce root reserves and starve plants.

•Apply spot applications of herbicides when shoots are at least 10 inches tall and before flowers open when plants are most susceptible to herbicides.

Common Weeds Of Kentucky Common blue violet (Viola sororia) is a short perennial weed (less than 6 inches tall) with heart-shaped leaves on long stems growing from a crown. Plants, which grow in clumps, are spread by seed and short, thick rhizomes. While common in moist areas, plants also tolerate dry sites once established.

Management: •Managing with herbicides is difficult.

•Cultivation spreads rhizomes.

•In small plantings, dig up individual clumps.

•Crop rotation is effective if rotational crop has more herbicide options.

Common Weeds Of Kentucky Common chickweed (Stellaria media) is a winter annual that germinates in autumn and produces small, white flowers in spring. Leaves are small (1⁄4 to 1⁄2 inch long), pointed at tips, and arranged opposite along stems. Plants are easily separated from their shallow fibrous root systems. Other closely related chickweeds (Cerastium spp.) may occasionally be found in plantings.

Management: •Apply a pre-emergent herbicide in autumn.

•Hand weed in spring when stems are fragile.

•Avoid cultivation after seed set to prevent spread.

Common Weeds Of Kentucky Dandelion (Taraxacum officinale) is a common yellowflowered perennial weed that grows as a rosette from a deep taproot. Oval leaves have wavy margins.

Management: •Cultivate or dig individual plants; however, new shoots can grow from dormant buds on root pieces remaining in the ground.

•Apply herbicides as spot applications.

Common Weeds Of Kentucky Hemp dogbane (Apocynum cannabinum) is a perennial weed spread by seed and rhizome. It can be confused with milkweed because stems exude milky sap when broken. Small leaves (2 to 5 inches long and 1 to 2 inches wide) are thick and have white veins on their upper surfaces. Leaves are paired on opposite sides of stems, and they may be attached directly to stems or have short petioles.

Management: •Cut repeatedly and/or cultivate at renovation.

Common Weeds Of Kentucky Horsenettle (Solanum carolinense) is a coarse perennial weed spread by seeds and rhizomes. Stems and leaves have scattered ¼- to ½-inch spines. White and yellow flowers produce green berries that turn yellow as they ripen.

Management: •Cut repeatedly and spot-treat with a systemic herbicide.

•Do not allow plants to go to seed; a single plant can produce up to 5,000 seeds.

Common Weeds Of Kentucky Lambsquarters (Chenopodium album) is a rapidly growing summer annual that can reach 6 feet in height. Erect stems branch freely and are often reddish or striped with pink, purple, or yellow. It is adaptable to most environmental conditions.

Management: •Mulch (to prevent seed germination).

•Apply pre-emergent herbicides (to prevent seed germination).

•Till (to destroy plants).

•Apply post-emergent herbicides (to destroy plants).

Common Weeds Of Kentucky Marestail/horseweed (Conyza canandensis) is a biennial weed that can reach heights of 3 to 6 feet. Seeds germinate throughout spring and early summer; plants mature and set seed the same year. Late-season plants overwinter in the rosette stage. One plant may release 200,000 seeds that disperse easily by wind.

Management: •Cultivate at renovation.

•Apply pre-emergent herbicides to prevent seed germination.

•Burn-down herbicides during seedling or rosette stages destroy young plants.

•Glyphosate-resistant marestail is becoming more common.

Common Weeds Of Kentucky Ragweed (Ambrosia artemisiifolia) is a broadleaved, branched annual with compound leaves (divided into leaflets on a single leaf). Leaves are arranged alternately in plant tops, but lower leaves have an opposite arrangement. This weed typically will not germinate after renovation as soil temperatures tend to be too high during July and August.

Management: •Early control is important.

•Cultivate early in the season and at renovation.

•Apply pre-emergent herbicides.

Common Weeds OF Kentucky Red deadnettle or purple deadnettle (Lamium purpureum) and henbit (Lamium amplexicaule) are members of the mint family. They are winter annuals that produce flowers in early spring. Plants have square stems and shallow roots. Upper leaves of L. purpureum are often reddish in color.

Management: •A limited number of preemergent herbicides are effective

Common Weeds Of Kentucky Other Names: Broad Leaf Dock, Bitter dock, blunt-leaved dock Life Cycle: Perennial Description: The plant grows as a rosestte of foliage with large leaves and produces a deep tap-root.

Other Names: Curly Leaf Dock, sour dock, yellow dock

Life Cycle: Perennial Description: Might be confused with broadleaf dock, however the leaves are narrower and markedly wavy on margins.

Common Weeds Of Kentucky Other Names: Daisy flea-bane Life Cycle: Winter annual; can be biennial Description: The plant begins as a basal rosette and as it matures, the leaves become more lancelolate. The daisy-like flowers are white with yellow centers.

Common Weeds Of Kentucky

Other Names: Field garlic Life Cycle: Perennial Description: Wild garlic is a perennial plant produced from bulblets. The leaves are grass-like, round and hollow, unlike wild onion which is flat and has solid leaves. The leaves emit pungent, onion-like odor when crushed.

Common Weeds Of Kentucky Other Names: Copperleaf, Hophornbeam Life Cycle: Annual Description: This plant is a summer annual which can grow to a height of 40 inches. The oval-shaped leaves have serrated edges with long petioles. The fruit is a pubescent capsule.

Common Weeds Of Kentucky Other Names: Life Cycle: Annual or biennial Description: The leaves are arranged alternately along the stem. The leaves are usually lobed and secrete a milky sap when crushed. Also, there are prickles located on the underside of the midrib as seen in this photo (top right). At maturity, the plant produces many small yellow flowers.

Common Weeds Of Kentucky Other Names: Beef-steak plant Life Cycle: Annual Description: Erect growth habit with green or purplishgreen leaves. Stems are square. When mature, the plants emit a distinctive minty odor. This plant is extremely toxic to all kinds of cattle, sheep and horses.

Common Weeds Of Kentucky Other Names: Crabgrass, Hairy fingergrass Life Cycle: Summer annual Description: Large crabgrass has hairy leaves and roots at the nodes. The leaves may turn red with age.

The most common crabgrass species in Kentucky is large crabgrass, but may also find smooth crabgrass (Digitaria ischaemum).

Common Weeds Of Kentucky Life Cycle: Perennial Description: Primarily a weed of turf, the buckhorn plantain can also become a problem in a poorly maintained pasture. Leaves are in a basal rosette.

Broadleaf Plantain

Buckhorn Plantain

Common Weeds Of Kentucky Other names: Yellow Foxtail, Bristly foxtail, foxtail, pearl millet, foxtail grass Life Cycle: Summer annual Description: Yellow foxtail is a clump-forming summer annual.

Mature plants can be as much as 3 feet in height. The seedhead is a yellow, bristly panicle and resembles a fox's tail.

Common Weeds OF Kentucky Other Names: Field nutsedge, nut-grasss cyperus, yellow nutgrass Life Cycle: Perennial Description: Triangular stem, leaves are yellow to light green in color, seedhead is yellow.

Questions