by Mark Czarnota

Some Troublesome Weeds
of Ornamentals!
by Dr. Mark Andrew Czarnota
UGA, Griffin Campus

My History
• Native of Pennsylvania
• University of Delaware (B.S.), Virginia Tech (M.S.),
Cornell (Ph.D)
• Worked for 3 years between those degrees
• Associate Professor and Extension Specialist at the
University of Georgia, Griffin
• 75% Extension, 25% Research
• All aspects of weed control in ornamentals, small
fruits, Christmas trees, and flower culture

Pre Herbicides for the Ornamental Industry
Trade Name
Active
Containers (C) /
Field (F)
Landscape Use
Tower (dimethenamid) F Y
Casoron (dichlobenil) F Y
Dimension (dithiopyr) F, C Y
Broadstar (flumioxazin) F, C N
Gallery (isoxaben) F, C Y
Pennant (metolachlor) F, C Y
Devrinol (napropamide) F, C Y
Surflan (oryzalin) F, C Y
Ronstar (oxadiazon) F, C Y
Pendulum (pendimethalin) F, C Y
Barricade (prodiamine) F, C Y
Kerb (pronamide) F N
Princep (simizine) F Y
Treflan (trifluralin) F, C Y

Post Herbicides for the Ornamental Industry
Non-Selective Herbicides
Trade Name Active
Reward (diquat)
Finale (glufosinate)
Roundup (glyphosate)
Goal (oxyfluorfen)
Scythe (pelargonic acid)
Grass Herbicides
Trade Name
Envoy Max
Acclaim Extra
Fusilade II
Segment (aka:
Vantage)
Trade Name
Active
(clethodim)
(fenoxaprop)
(fluazifop-p-buytl)
(sethoxydim)
Selective Broadleaf Herbicides
Basagran
Lontrel
Sedgehammer
(aka: Manage)
Image
Garlon
Active
(bentazon)
(clopyralid)
(halosulfuron)
(imazaquin)
(triclopyr)

Combo Herbicides
•Dry formulation
•Usually contain a burndown
herbicide (oxyfluorfen) and a
preemergent herbicide
(pendimethalin)
•Easy to apply and forgiving

Combination Herbicide for the
Ornamental Industry
Trade Name Formulation Active
OH2
3 GR
oxyfluorfen /
pendimenthalin
Containers (C) / Field (F) /
Landscape (L)
F, C, L
Rout 3 GR oxyfluorfen / oryzalin F, C, L
Kansel+
3.25 GR
oxadiazon /
pendimethalin
F, C, L
Snapshot 2.5 GR isoxaben / trifluralin F, C, L
Showcase
2.5 GR
isoxaben / trifluralin /
oxyfluorfen
F, C, L
XL (Amaze) 2 GR benefin / oryzalin F, C, L
Regal O-O
3 GR
oxyfluorfen /
oxadiazon
F, C, L
RegalStar 1.2 GR oxadiazon / prodiamine F, C, L
Freehand
1.75 GR
dimetnenamid /
pendimethalin
F, C, L
Biathlon
2.75 GR
oxyfluorfen /
prodiamine
F, C, L

Herbicides for Herbeacous
Annuals and Perennials
Trade Name Formulation Active
Kansel+
3.25 GR
oxadiazon /
pendimethalin
Containers (C) / Field
(F) / Landscape (L)
F, C, L
Snapshot 2.5 GR isoxaben / trifluralin F, C, L
XL (Amaze) 2 GR benefin / oryzalin F, C, L
Freehand
1.75 GR
Dimetnenamid /
pendimethalin
F, C, L
Treflan (trifluralin) F, C Y

Annual Weeds
• Our state is very diverse, and if it does not get
cold enough for long enough, many annuals will
not die!
• Use preemergence herbicides - most give a
control barrier for 6 to 8 weeks!
• One exception is plants in the Euphorbiaceae
family. Plants in this family are very tolerant to
DNA herbicides (i.e. Surflan, Baricade, Treflan)

Annual Weeds
• Most annuals have a very long germination
window (3 months or greater)
• Several can go from seed to flower in ≤ 7 days
• Encourage clients to maintain a 2 to 4 inch layer
of mulch, as this can eliminate much of your
annual weed problems (~80%).
• Once seeds have germinated few selective
herbicides are available.

Bittercress
Hairy bittercress (Cardamine hirsuta)

Bittercress Control
Control:
• Seed to flower in less than 14 days
• Seeds forcibly extracted
• Ronstar is an excellent pre herbicide on this
plant
• Mainly seen when temperatures are in the
60’s

Oxalis
Woodsorrel (Oxalis corniculata and O. stricta)

Control:
Bittercress Control
• Seed to flower in less than 14 days
• Seeds forcibly extracted
• Ronstar is an excellent pre herbicide on this
plant
• Mainly seen when temperatures are in the
60’s
• Creeping wood sorrel (Oxalis corniculata) is a
perennial

Spurge
Spurge (Euphorbia or Chamaesyce spp.)

Phyllanthus
Phyllanthus (Phyllanthus spp.)

Spruge / Phyllanthus Control
Control:
• Seedling usually seen with warmer soil
temperatures (≥ 70 ºF)
• Lots of seed production
• DNA’s are very poor at controlling these
plants

Mulberry Weed
Mulberry weed (Fatoua villosa sp.)

Control:
Mulberry Weed Control
• Seed to flower in less than 14 days
• Lots of seed production
• Most pre herbicides have good activity

Eclipta
Eclipta (Eclipta prostrata)

Control:
Eclipta Control
• Most pre herbicides have good activity
• Plant roots easily from stem pieces
• Difficult to hand remove once established
• Lots of seed production
• Tolerant of glyphosate

Crabgrass
Crabgrass (Digitaria spp.)

Crabgrass Control
Control:
• Always crabgrass and annual grasses
• 2 to 4 inch mulch layer smoother seedlings
• Most preemergence herbicides work well
• Usually seen when soil are in the 70’s
• Post herbicides give us good selective control

Vetch
Vetch (Vicia spp.)

Control:
Vetch Control
• Mainly a weed in landscape
• Some preemergence herbicides are poor (i.e.
DNA’s, BroadStar and Gallery much better)
• Lontrel give good selective postemergence
control in several established ornamentals
(Junipers, Holly, Azalea, etc.)

Morningglory
Morningglory (Ipomoea spp.)

Morningglory Control
Control:
• Anything with isoxaben (Gallery, Snapshot),
simazine (Princep), prodiamine (Barricade)
• Don’t confuse with bindweeds
• Post control spot treat with glyphosate
• Might get sulfentrazone one day

Perennial Weeds
• Can be controlled with preemergence herbicides
if controlling from seed stage
• Once plant is established selective control can be
difficult (only Basagran, Halosulfuron, Lontrel,
and Image)

Yellow and Purple Nutsedge
Yellow nutsedge
(Cyperus esculentus)
Purple nutsedge
(Cyperus rotundus)

Control:
Nutsedge Control
• Hand removal and cultivation is a waste of
time!
• Sedgehammer® is the bomb as far as
postemergence selective control
• Purple nutsedge is the #1 weed in the world
and Yellow is considered a top 10 weed.
• Yellow nutsedge is also known as Chufa

Bermudagrass (Cynodon dactylon)
Burmudagrass

Burmudagrass control
• All the popular grass herbicide will provide selective
control, but multiple applications will be necessary to
control
• Non-Selective Control can be achieved with the use of
glyphosate, but directed sprays must at least >5% spray
solutions using at least 41% concentrates to make that
5% spray solution

Dichondra
Dichondra (Dichondra spp.)

Control:
Dichondra Control
• Hand removal and cultivation is a waste of
time!
• No selective herbicide available
• Post directing glyphosate, be sure to use at
least a 5% spray solution using at least a
41% concentrate to make
• Plant use as an alternative turfgrass in
certain parts of the country

Pennywort
Pennywort (Hydrocotyle spp.)

Control:
Pennywort Control
• Hand removal and cultivation is a waste of
time!
• Lontrel is only post selective herbicide
available, but requires multiple applications
• Post directing glyphosate, be sure to use at
least a 5% spray solution using at least a
41% concentrate to make
• Plant sold as an ornamental (water gardens)

Field / Hedge Bindweed
Field bindweed (Convolvulus arvensis)
Hedge bindweed (Calystegia sepium)

Field / Hedge Bindweed
Control:
• Physical removal of the Vine is difficult
because of tuber / rhizome system.
• Paint or spray vines, cut vine back and
wait for reflush and spray with
glyphosate (5 to 10%) or Lontrel
• Repeat applications

Florida Betony
Florida Betony (Stachys floridana)

Florida Betony
Control:
• Physical removal of the plant is difficult
because of tuber / rhizome system.
• Spot treat foliage with 5% Roundup
(glyphosate) solution
• Casoron (dichlobenil) can be applied
over-the-top of most woody ornamentals,
and does a good job of selective control

Mugwort
Mugwort (Artemisia vulgaris)

Control:
Mugwort Control
• Hand removal and cultivation is a waste of time!
• Lontrel and Basagran provide good postemergence
selective control (Basagran will require multiple
applications
• Post directing glyphosate, be sure to use at least a
5% spray solution using at least a 41% concentrate
to make
• Variegated form of the plant sold is sold as a
ornamental

Dogfennel
Dogfennel (Eupatoium capillifolium)

Dogfennel Control
Control:
• Difficult to hand removal established plants!
• Most preemergence herbicides will control at
seedling stage
• Lontrel provides excellent postemergence selective
control, but may require multiple applications

Liverwort

Liverwort

Liverwort Control
Control:
• Hand removal
• Broadstar / Sureguard (flumioxazin),
Ronstar (oxadiazon), acetic acid, oregano oil
and others show potential
• Limit watering as much as possible
• Mogeton (quinoclamine) was great but gone

Woody Weed Control
• Trees, Shrubs, and Vines can be
controlled with stump or stem
applications.
• Roundup and Garlon can be used
at 50% or full strength, and
painted to stems, fresh cut stems,
and stumps.
• In unmanaged areas, you can do a
basal bark application with
Garlon and other herbicides.
Cut
Paint

Chinese Privet (Ligustrum sinense)

Privet Control
Control:
• Physical removal of the shrub
• Cut shrub back, and paint stumps with
concentrated Roundup or Garlon (triclopyr)
• Dormant basal bark application (Garlon)
• After cutting shrub back, wait for reflush (8
to 10 inches) and spray with Roundup (5%
solution) or Garlon

English Ivy Hedera helix

Control:
English Ivy Control
• Physical removal of the vine is difficult.
• If climbing something, cut vine as low as
possible (remove a chunk), and paint cut
stem (root side) with concentrated Roundup
or Garlon (triclopyr)
• If a ground cover, mow or cut to ground.
Wait for reflush (4 to 6 inches) and spray
with Roundup (5 to 10% solution) or Garlon

Bamboo
‣Planted for ornamental uses
and escaped – most Phyllostachy
spp.
‣Growth characteristics makes
bamboo difficult to control
Phyllostachys spp.

Results
2004 Control of bamboo (Phyllostachys rubromarginata) with selected
herbicides.
Bamboo Control
Treatment Rate 8 WAT 16 WAT 25 WAT 61 WAT
kg ai/ha ---------- % ------------ ------------
-
Untreated 0 b 0 b 0 c 0 c
Dichlobenil 17.9 23 b 23 b 0 c 7 c
Glyphosate 4.5 88 a 88 a 82 b 47 b
Imazapyr 1.7 87 a 87 a 95 a 88 a
LSD (0.05) 25 25 3 15

Results
Imazapyr 1.7 kg ai/ha
Glyphosate 4.5 kg ai/ha

Blackberry
Blackberry and others (Rubus spp.)

Blackberry Control
• Garlon 3A (triclopyr) can provide selective control, and
glyphosate can provide non-selective control.
• One method of controlling is to paint a one foot section of
the Blackberry cane with concentrated triclopyr or
glyphosate
• Post directed sprays can be made, but will require 5% spray
solutions of either triclopyr or glyphosate (at least a 41%
concentrate)
• Multiple applications my be required

Plant Books
• Manual of Vascular Flora of the Carolinas,
by Radford, Ahles, and Bell (Publisher: The
University of North Carolina Press)
• Flora of North America (Publisher: Oxford
Press)

Weed Books
• Weeds of the NorthEast, by Uva, Neal, Ditomaso
(Publisher: Cornell University Press)
• Color Atlas of Turfgrass Weeds, by McCarty,
Everest, Hall, Murphy, Yelverton (Publisher: Ann
Arbor Press)
• Weeds of the West, by Whitson, Burrill, Dewey,
Cudney, Nelson, Lee, Parker (Publisher:
University of Wyoming)
• Forest Plants of the Southeast and Their Wildlife
Uses, by Miller and Miller (Publisher: Southern
Weed Science Society)

Questions!