Weed Control in Homeowner Ornamentals Tim R Murphy

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 Fabric Mulches Plastic or fabric thickness affects the degree of weed suppression. Ø Clear and colored plastics that allow light penetration produce high temperatures in the upper surface. Ø This build up of heat, solarization, kills germinating weed seeds. Ø

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. Ø These mulches also shade and physically hinder germinating seedlings Ø

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

Mechanical Control Hand Pulling and Hoeing Ø Still used for weed control in high value crops Ø Best control with small weeds <4 inches Ø Must understand how the weed develops (annuals vs. perennials)

Hand Weed Control Advantages Disadvantages keeps you in shape environmentally friendly controls most weeds Inexpensive (if done by self repetition is a must can stimulate germination must be timely

Mechanical Control Tillage Ø Controls many weeds that have emerged Ø Incorporate Ø Prepares fertilizers, lime seed or plant beds

Tillage Practices Advantages Disadvantages control most weeds quick and easy expensive? ? can’t get too close to crop – root pruning noise pollution

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-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