Problem Weeds of Turfgrasses

Tim R. Murphy

Crop and Soil Sciences

The University of Georgia

Why control weeds?

• Reduce crop yields and quality• Lower aesthetic appeal and property value• Some are allergens or poisonous• Disrupt native ecosystems• Harbor insects and diseases• Interfere with right-of-way safety and

transmissions

Weed Management Strategy

• Identify weed, life cycle, habitat

• Institute Control Procedures– Preventive

– Mechanical

– Biological

– Cultural

– Chemical

Virginia buttonweed

Virginia buttonweed (Diodia virginiana)

• Warm-season perennial broadleaf

• Reproduction– creeping stems

– creeping roots

– above and below ground seed production

Virginia buttonweed

• Seed germination

- optimum at 85 to 95 F.

- no germination < 70 F.

- optimum depth 1.0 to 1.5 inches

• Shoot emergence

- root fragments 0.25 inch long can

produce shoots from 8 inch soil depth

Virginia buttonweed - Control

• 2,4-D + 2,4-DP Good• 2,4-D + dicamba Good• 2,4-D+MCPP+dicamba Good• Research at MSU show formulations high in

2,4-D concentration provide better control (ex. Trimec Classic, Escalade)

• Spray regrowth when noted (21 to 35 days)

Virginia buttonweed - Control

• Ronstar - seed only

• Princep - seed only

• Confront, Manor - fair control (variable)

• Monument, Katana – good control (variable)

• Glyphosate - the last resort!

Sedge Herbicides - Turfgrasses

• Basagran T/O - yellow, annual sedges• Manage, SedgeHammer - yellow, purple, annual

sedges• Monument - yellow, purple, annual sedges• Katana - yellow, purple, annual sedges• MSMA/DSMA - yellow, purple, annual sedges• Image - yellow, purple, annual sedges• Certainty – yellow, purple, annual sedges• Pennant - yellow, annual sedges

Green (perennial) kyllinga

Kyllinga spp. (Kyllinga spp.)

• Sedge family

• Annuals and perennials

• Reproduce by seed and rhizomes

• No tuber formation

• Thrive in wet soils

• Increasing in severity

• Lack of MSMA use??

Kyllinga spp. - Control

• Image• Image + MSMA• Manage, SedgeHammer• Katana• Monument• Certainty• MSMA/DSMA

• Repeat applications will be needed

Sedge control ratings.

HerbicideAnnual Sedge

Purple Nutsedge

YellowNutsedge

Annual Kyllinga

Green Kyllinga

Pennant G F G F-G P

Certainty G G-E G-E G G-E

Basagran T/O G P G F-G F-G

Image G F-G P-F G G

Sedgehammer G G G G F-G

MSMA/DSMA G P-F F G G

Image+MSMA G G-E G G G

Monument ?? G-E G G G-E

Violet spp. (perennial)

Violets spp. (Viola spp.)

• Annuals and perennials• Shade or full sun• Reproduce by seed (rhizomes)• 2- and 3-way products - P to F• 2 appl. Confront, 3 to 6 wks apart• 2 appl. Chaser, Turflon II Amine. 4 wks apart• Katana, Manor, Blade

Wild garlic

Wild Garlic/Onion (Allium vineale and canadense)

• Cool-season perennial,reproduces by seed, aerial bulbils and underground bulbs and bulblets

• 2,4-D and other phenoxy products, 2 appl. 6 wks apart, 2 to 3 years

• Image - apply after dormancy, mow 1 to 2 wks after application

• Manor, Blade

Doveweed

Doveweed (Murdannia nudiflora)

• Summer annual, reproduces by seed

• fleshy stems, root at nodes

• 3 appl. MSMA + 2,4-D

• 2 appl. MSMA + Sencor

• Atrazine, 2 applications, 3 weeks apart

• 2 appl. Trimec Southern (14 d intervals)

Doveweed

• Ineffective Herbicides

- Basagran T/O

- Confront

- Vanquish

- Manor, Blade

Spreading dayflower

Spreading Dayflower (Commelina diffusa)

• Summer annual

• Reproduces by seed and stem fragments

• MSMA + Sencor

• Basagran T/O, Prompt

• MSMA

• Turflon II Amine (2,4-D + triclopyr)

Annual blue-eyed grass

Annual Blueeyed-grass(Sisyrinchium spp.)

• Annuals and perennials, Member of Iris family• Reproduce by seed• Thrives in compacted soils, some species like

moist soils• TranXit• Triazines in late fall• 2 appl. MSMA + Sencor, 14 d interval

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

Chamberbitter & Longstalked Phyllanthus Control

• atrazine, simazine, 2 appl., 3 wks apart

• Ronstar - Pre (no home lawns)

• Gallery - Pre

• MSMA, 2 to 3 appl., 7 days apart ???

• 2,4-D+MCPP+dicamba ????

• Manor, Blade????

Prostrate spurge - summer annual

Postemergence: Manor, Blade, Sencor, Trimec, Monument

Preemergence: Simazine, atrazine, Gallery

summer annual

fireweed

Postemergence : 2- and 3-way growth regulator herbicides, Manor, Blade.

Preemergence products are not very effective or provide only short term control.

American burnweed (fireweed)

Pennywort or dollarweed

perennial

•Atrazine or simazine applied twice, 30 days apart.

•Prompt, Image, Manor, Blade.

•2 or 3-way broadleaf mixtures applied 7 days apart are also effective in tolerant turfgrasses.

Dichondra, rhizomatous perennial

Controlled by repeat applications of atrazine, 30 days apart.

2 and 3-way growth regulator herbicides. Confront is a little better than Trimec related compounds.

*Monument

Lawn burweed (spurweed)

Lawn Burweed - Soliva pterosperma

• Compositae (aster family)

• spurweed, sandbur

• winter annual, reproduces by seed

• opposite leaves

• fruits with sharp spines

Lawn Burweed Control

• atrazine, simazine - Pre or Post

• Gallery - Pre, early fall

• 2,4-D+MCPP+dicamba, repeat applications may be necessary

• Manor, Blade

• Katana

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

• atrazine - F-G

• 2,4-D - G

• 2,4-D+MCPP+dicamba - G

• Roundup, Finale

• Manor, Blade

Annual bluegrass – Poa annua

• Winter annual, but perennial biotypes also found on bentgrass greens

• Germinates late summer-fall at soil temperatures around 70 F.

• Second germination flush in mid- to late-winter

Continuous annual bluegrass seedgermination occurred from mid-Nov.through early January in Knoxville, TN.

Callahan and McDonald, 1992

Annual bluegrass control

Preemergence Control• Barricade, Pendulum• Surflan, Dimension• Balan, Ronstar• Kerb• Atrazine, Simazine

annual bluegrass

Boat shaped leaf tip

Non-Overseeded Bermudagrass

• Triazines – standard, but resistance increasing– Kerb – works, costly, lateral run-off

– Pre’s – work, but DNA resistance is here

– Glyphosate – works, partial dormancy

– Diquat – ineffective

• Revolver, TranXit, Monument, Certainty

Overseeded Bermudagrass

• Options for annual bluegrass• Kerb - 60 to 90 days (or charcoal)

– Dimension – 6 to 8 wks– Barricade – 8 to 10 wks (supplemental label)– Balan – low rate, 6 weeks– Rubigan – cost limits use to greens– Prograss – greenup issue – TranXit and Revolver – 2 weeks before seeding

Poa Control with Kerb

• Excellent for annual bluegrass

• Will move with water and damage cool-season grasses

Kerb movement onto bentgrass

Annual Bluegrass Control

Bentgrass Greens• paclobutrazol (Trimmit) at 0.25 lb/ac in the fall

followed by 2 to 3 applications in the spring.

• Pre’s tend to select for the perennial type Poa annua

• Roundup is effective• Monument, Revolver, Katana are effective• Kerb and Illoxan provides some control• Reward and Finale ineffective• Manor, Blade partial control

Italian Ryegrass

Italian Ryegrass Control

Herbicide Rate/A % Ryegrass Control

Roundup 2 qt 93

Finale 2 qt 43

Reward 2 qt 10

Illoxan 1.25 lb 47

Manor 1 oz 40

Overseeding

Clumpy perennial ryegrass

Monument, Revolver,

Katana

cool-season perennial

Tall Fescue

• Roundup (risky)

• Kerb during winter months

• Corsair, Monument, Revolver, Certainty, Katana

• Repeat applications of MSMA

• Usually 3 to 4 treatments required on a 5 to 7 day schedule

Dallisgrass

Dallisgrass – New Option

• Apply MSMA at normal rate

• Follow 2 weeks later with spot treatment of Revolver at 1.0 fl. oz/gallon

• Follow 7 to 10 days later with MSMA at normal rate

Roundup Rate and Bermudagrass Control

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Roundup Rate/Acre

53 DAT 116 DAT

Bermuda Control with Roundup – 1 yr.

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Rate Qt/Acre / No. of Apps.

Bermuda Suppression in Zoysiagrass

• Acclaim Extra – 20.0 fl. ozs./acre– Apply every 4 weeks during growing season

• Fusilade II– 3.0 to 4.0 fl. ozs./acre – Apply every 4 weeks during growing season

• Tank-mix with Turflon Ester at 1.0 qt./acre will improve control

Bermuda Suppression in Tall Fescue

• Apply 4 to 5 applications per year of Acclaim Extra at 20.0 fl. ozs./acre. Add Turflon Ester at 1.0 qt./acre to improve control. Apply every 4 weeks.

• Apply 2 applications (spring + fall) of Fusilade II at 5 to 6 fl. ozs./acre per year for 2 years

Bermuda Suppression in Centipedegrass

• Apply 2 applications (spring + 3 to 4 wks) of Vantage at 2.25 pts./acre per year for 2 years

• Apply 2 applications (spring + 3 to 4 wks) of Envoy at 34 fl. ozs./acre per year for 2 years (sod farm label)

Bermuda Suppression in St. Augustinegrass

• Prograss + Atrazine (2.0 gals. + 2.0 qts./acre)• 2 to 3 applications

– 1st – 2 to 3 wks after spring growth resumes– 2nd – 30 days later– 3rd - 30 days later if regrowth occurs

• Temp. injury and stunting to St. Aug. will occur• Avoid spray overlap or injury will increase

rhizome

seedhead

Bahiagrass

Repeat MSMA

Manor, Blade

rhizomes

www.amazon.com

* 214 weed species*575 color photos*Control info for each weed

$95.00

Turfgrass Web Page

• www.georgiaturf.com or .org

• 437 photographs of 193 weeds

• Control recommendations

• Popular articles

• Links to turfgrass organizations, GA automated weather network