Weed Control in Homeowner Ornamentals

Tim R. Murphy

The University of Georgia

Landscape

Ornamental Weed Control Options

• Hand-removal, hoeing

• Mulches

• Landscape fabrics

• Herbicides

#1 Home Owner Question

What can I spray on *&^#@!? weed to kill it and how much do I need??

Mechanical Control

Plastic or 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 weed seeds.

Fabric Mulches

Landscape Fabrics

• Expensive

• Limited commercial use

• Very good option for homeowners

• Use high quality, non-woven, fused fabric

• 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

control most weeds expensive??good use of “waste” handling is often materials a painConserves water

Advantages Disadvantages

Mechanical Control

Still used for weed control in high value crops

Best control with small weeds <4 inches Must understand how the weed develops

(annuals vs. perennials)

Hand Pulling and Hoeing

Hand Weed Control

keeps you in shaperepetition is a mustenvironmentally friendly can stimulate germinationcontrols most weeds must be timely Inexpensive (if done by self

Advantages Disadvantages

Mechanical Control

Controls many weeds that have emerged

Incorporate fertilizers, lime

Prepares seed or plant beds

Tillage

Tillage Practices

control most weeds expensive??quick and easy can’t get too close to crop – root pruning

noise pollution

Advantages Disadvantages

HERBICIDES

Ornamental – Homeowner Herbicides

• Annual grass control available– Preemergence and postemergence

• Pre and Post broadleaf weed control is difficult

• Use post graminicides for perennial grass control

• Vines, woody plant control is exceeding difficult

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

Homeowner - Selective POST Grass Control Herbicides

• Sethoxydim - Vantage, Hi-Yield Poast– reseeding restriction: not listed

• Fluazifop - Dexol Grassout

Greenlight Bermudagrass Killer

Ortho Grass-B-Gon

- reseeding restriction: 2 months

Ornamentals – 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.

Florida betony

Florida Betony - Stachys floridana

• Labitae (mint family)

• “Rattlesnake weed”

• perennial

• reproduces primarily by tubers

• opposite, serrated leaves

• occurs in turf and ornamentals

Florida Betony Control

• Roundup, Finale

• Casoron applied in winter, very difficult to find, can be ordered at Southern States, commercial herbicide stores

• Use landscape fabric in ornamentals

Bamboo

• Phyllostachys aurea

• Grass family

• rhizomatous

• rarely fruits

• no wildlife value

• full sun, partial shade

• native to China

Bamboo Control

• No herbicide is labeled for the control of bamboo.

Bamboo Control

• Roundup Pro, 2% v/v, apply to regrowth 3 to 6 feet tall, repeat, not on label

• Roundup Pro, 33% v/v, apply with gloved hand to husk stage, repeat, not on label

• MSMA, 2% v/v, will “knock” leaves off, repeat

• Mechanical barrier, 30 inches deep

Phyllanthus spp. - Biology

• Summer annuals

• Spurge family

• Seeds require light

• Tolerates full sun and moderate shade

Chamberbitter, niruri, gripeweed

Chamberbitter - Phyllanthus niruri

• Euphorbiaceae (spurge family)• niruri, gripeweed, leafflower• summer annual, reproduces by seed• alternate leaves, numerous leaflets• inconspicuous flowers• stalkless green, round fruit• no milky juice

Longstalked Phyllanthus

Longstalked Phyllanthus (Phyllanthus tenellus)

• Euphorbiaceae (spurge family)

• summer annual, reproduces by seed

• alternate leaves, numerous leaflets

• inconspicuous flowers

• stalked green, round fruit

• no milky juice

Phyllanthus spp. - Control

• Use mulch

• Apply early spring

Phyllanthus spp. Preemergence Control

• Ronstar (not labeled for use in home landscapes)

• Rout (OHII - slightly less effective)

• Surflan + Gallery (Snapshot TG - less effective)

• Prodiamine (Factor, Endurance, Barricade)

• Gallery

Phyllanthus spp. Postemergence Control

• Roundup Pro

• Finale

• Reward LS

Phyllanthus spp. Ineffective Herbicides

• Basagran T/O

• Image

• MSMA

• Pennant

• Pendimethalin

• Balan

Isoxaben Products - Homeowners

• PRE herbicide for control of annual broadleaf weeds

• Primarily used in woody ornamentals

• Gallery

• Greenlight Portrait

• Reseeding restrictions - 2 months

EPTC Products - Homeowners

• PRE control of annual grass and broadleaf weeds

• Woody ornamentals, some flowers, groundcovers

• Preen for Groundcovers

Homeowner - Nutsedge Herbicides

• Image – imazaquin – reseeding restriction: 6 weeks

• Manage – halosulfuron -reseeding restriction: 4 weeks

• Bentazon– Basagran T/O, Hi-Yield Basagran– reseeding restriction: 0 week

Sedge Herbicides -Ornamentals

• Basagran T/O - yellow, annual sedges

• Manage - yellow, purple, annual sedges

• Image - yellow, purple, annual sedges

• Pennant - yellow, annual sedges– Preemergence only– No homeowner package available

Basagran T/0 - Ornamentals

• Directed spray around base of ornamentals

• Over-the-Top– Hollies, ornamental cabbage, pachysandra– Liriope, impatiens, marigold– English ivy, petunia, ajuga

• “Safer”option for yellow nutsedge than Roundup Pro

Manage - Ornamentals

• Post-directed around woody ornamentals

• New-transplants- wait 3 months

• Do not use in annuals or herbaceous perennials

• May be applied 4 weeks in advance of transplanting woody ornamentals

Image - Ornamentals

• Over-the-top– Junipers, Burford hollies, Helleri holly, Indian hawthorne,

– Liriope, mondograss, hostas, Red tip photinia

– Pachysandra, Asiatic & Confederate jasmine

• Do not apply over root zone of non-listed ornamentals

• Azalea, ligustrum, viburnum, pieris, abelia are severely injured by Image

Dodder

Dodder - Cuscuta spp.

• Convolvulaceae (morningglory family)• rootless, leafless parasitic annuals• “yellow spaghetti”• prolific seed producer• germinates early spring• 8 species known in Georgia• wide host range on broadleaf plants

Dodder Control - Ornamentals

• Fumigate - Basamid

• Casoron, Norosac - woody ornamentals, may be difficult to find

• Dacthal - dropped by manufacturer

• Kerb - woody ornamentals, Restricted Use Herbicide

• Roundup, Finale