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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
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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(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
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
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/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 (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 (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 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 - 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 (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
fireweed American burnweed (fireweed) Postemergence : 2- and 3-way growth regulator herbicides, Manor, Blade. Preemergence products are not very effective or provide only short term control. summer annual
perennial Pennywort or dollarweed • 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.
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 Dichondra, rhizomatous perennial
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 - 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 seed germination 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 Boat shaped leaf tip annual bluegrass
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 Kerb movement onto bentgrass • Excellent for annual bluegrass • Will move with water and damage cool-season grasses
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
Italian Ryegrass • Roundup is effective • Monument, Revolver, Katana are effective • Kerb and Illoxan provides some control • Reward and Finale ineffective • Manor, Blade partial control
Clumpy perennial ryegrass Monument, Revolver, Katana Overseeding
Tall Fescue • Roundup (risky) • Kerbduring winter months • Corsair, Monument, Revolver, Certainty, Katana cool-season perennial