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Sugarcane Weed Identification and Control with Herbicides

Les Baucum

Calvin Odero

Ron Rice

North Florida Research & Education Center

Quincy, FL

November 7, 2011

What is a weed?

• Plant growing where is not wanted

• Plant out of place

• Plant that is a nuisance

• Plant that is undesirable

Weed classification

• Weeds come in all growth forms

• May be classified as

– Grass

– Grass-like (sedge)

– Broadleaf

• Forbs

• Succulents

• Shrubs

Monocots

Dicots

Helpful ID characteristics

• Morphology - structure, shape, and

orientation

– Is it a broadleaf, grass, or sedge?

– Ligule characteristics for grasses

– Inflorescence - if present can make things

easier!!

Leaf type, shape, and texture

Leaf arrangement

Alternate

Opposite

Basal Whorl

Whorled

Root type

Tap Fibrous

Inflorescence

Panicle

Spike

Umbel

Head

Vegetative reproductive structures

Tubers Stolon

Rhizome Plantlets

Monocots: grasses and sedges

Grasses Sedges (Grass-like)

Stems • Hollow or flattened

• Occasionally solid

• Nodes (jointed)

• Solid

• Triangular (3-sided)

• Without nodes

Leaves • Parallel veins

• 2 sides

• Parallel veins

• 3 sides

Flowers • Small

• Inconspicuous

• Small

• Inconspicuous

Example • Goosegrass • Yellow nutsedge

Auricles

Dicots: broadleaf plants

• Two cotyledons

• Primary root often

becomes a strong tap

root with smaller

secondary roots

• Leaves are usually

net veined and broad

at the base with a

petiole or stalk

Dicots: broadleaf plants

Forbs

Shrubs Succulents

Stems • Solid

• Pithy

• Solid

• Growth rings

• Fleshy, thick

• Sharp spines

Leaves • Net-veined • Net-veined • Small, fleshy

• Seldom present

Flowers • Small or large

• Colored

• Showy

• Small

• Showy

• Showy

Example • Common

lambsquarters

• Lantana • Cacti

Sugarcane weed control methods

• Crop competition

– Good stand, rapid & uniform growth, close-in • Shade soils and small weeds

• Mechanical

– Manual i.e. pulling, hand hoeing

– Plowing, disking

• Chemical control

– Herbicides • Soil (PRE) & foliar (POST) applied

Weeds often found in sugarcane and their

control

Crabgrass (Digitaria spp.)

• Very wide first leaf

• Initial clumping growth progressing to

prostrate, tillering

• Visible membranous ligule

• Can be very hairy, or hairless, depending

on species

Crabgrass (Digitaria spp.)

Control

• PRE – Prowl, Atrazine, Metribuzin

• POST – Asulox, Envoke or Asulox + Envoke

• Easier to control when small

Torpedograss (Panicum repens L.)

• Perennial with robust, creeping, sharply pointed rhizomes

• Leaf blade stiff and erect

• Hairs on upper and lower leaf surface

• Seedheads with stiff, ascending branches

• Occurs in wet areas

Torpedograss (Panicum repens L.)

Control

• Rhizome, buds must be destroyed for good control

• Mechanical operations that fracture rhizomes can actually result in increased populations

• Glyphosate (multiple applications) or Arsenal in noncrop areas

Fall panicum (Panicum dichotomiflorum)

• Most common grass in the area

• Relatively easy to identify

– Stem can be hairy or smooth

– Hairy when young

– Ligule fringe of hairs

– Round stem

– Widely dispersed seedhead

Control

• PRE – Prowl, Atrazine, Metribuzin

• POST – Asulox, Envoke or Asulox + Envoke

• Easier to control when small

Fall panicum (Panicum dichotomiflorum)

Wild oat (Sorghum almum)

• Not really an oat

• Closely related to

johnsongrass

– No rhizomes

– Large, membranous

ligule

– Robust plant

Wild oat (Sorghum almum)

Control

• PRE – Prowl, Atrazine, Metribuzin

• POST – Asulox, Envoke or Asulox + Envoke

• Limited experience with S. almum as a specific target

Alexandergrass & Broadleaf panicum

Broadleaf panicum (Urochloa adspersa)

• Relatively prostrate growth – Wide leaves with wavy

margins

– Round stems

– Usually dark green in color

– Very similar to alexandergrass

Broadleaf panicum (Urochloa adspersa)

Control

• PRE - Prowl, Atrazine, Metribuzin

• POST - Asulox or Envoke + Asulam

• Can be difficult

• Much easier to control when small

Alexandergrass (Brachiaria plantaginea)

• Relatively prostrate growth

• Somewhat wide leaves with straight

margins

• Round stems

• Usually light green in color

• Very similar to broadleaf panicum

– Leaves narrower (usually)

– Margins straight rather than wavy (usually)

Alexandergrass (Brachiaria plantaginea)

Control

• PRE - Prowl, Atrazine, Metribuzin

• POST - Asulox or Envoke + Asulox

• Can be difficult to control

• Much easier to control when small

Guineagrass (Panicum maximum)

• Some plants are extremely hairy, while

others are hairless

• Small plants have narrow leaves

• Becomes very large

• Highly branched seedhead

• Round stem

• Can look similar to Sorghum almum

– Sorghum almum shouldn’t be hairy

Guineagrass (Panicum maximum)

Control

• PRE - Prowl, Atrazine, Metribuzin

• POST - Asulox or Envoke + Asulox

• Need a quality surfactant to penetrate hairs

• Can be difficult to control

• Much easier to control when small

Bermudagrass (Cynodon dactylon)

• Easy to identify • Small leaves

• Rhizomes and stolons

• Mat forming

• Ligule fringe of short hairs (hard to see)

• Produces seed and spreads vegetatively

Bermudagrass (Cynodon dactylon)

Control

• PRE - Prowl can suppress from seed

• No selective POST control

• Must be controlled during fallow with multiple applications of glyphosate

Goosegrass (Eleusine indica)

• Found in many fields

• Low growing

– Very white, flattened

stems

– Looks like it has been

stepped on

– Probably not

competitive

Goosegrass (Eleusine indica)

Control

• PRE - Prowl, Atrazine, Metribuzin

• POST - Asulox or Envoke + Asulox

• Much easier to control when small

Pigweeds

(Amaranthus spp.) • Spiny amaranth is most

common – Large, upright growth

habit, entire leaves

– Very evident spines located at nodes

• Livid amaranth – Can be prostrate or erect

– Notched leaf tips

Alligatorweed (Alternanthera philoxeroides)

• Common in wet areas

of the EAA

– Often spread by

cultivation

– Low growing

• Hollow stems when

growing in wet spots

• Opposite leaves

• Small white blooms

Common lambsquarters (Chenopodium album)

• Common during the

cooler months

– Dec, Jan

• Can be difficult to

control due to waxy

leaf surface that

leaves a white-gray

color

Common purslane (Portulaca oleracea)

• Probably not competitive

• Prostrate, succulent

• Leaves small, smooth, opposite or alternate

• Red stems

• Small, yellow flowers

Common ragweed (Ambrosia artemisiifolia)

• Deeply dissected leaves

• Many hairs on upper and

lower surfaces

• Long seedhead at top of

plant

• Yellow/white flowers in

multiples

Ragweed parthenium

(Parthenium hysterophorus)

• Less common than common ragweed

– Common along canals, ditch-banks, noncrop areas

• Leaves less deeply dissected

– Divisions don’t go all the way to the stem

• White flowers

– Single, not multiples

Ragweed parthenium

(Parthenium hysterophorus)

Dayflower (Commelina spp.)

• Common in open

areas, field edges

– Small, probably not

competitive

– Prostrate growth habit

– Parallel veins on

leaves

– Actually a monocot

– Blue flowers

American black nightshade

(Solanum americanum)

• Becoming more

common in EAA

– Alternate leaves

• Usually entire

to somewhat

lobed

– Purple fruit

– Seems quite

competitive

Control of broadleaf weeds

• PRE- most can be controlled with Atrazine,

Metribuzin, and Evik

• POST - 2,4-D or Dicamba work well for most

• POST – Atrazine + Callisto works well too

• Envoke can be used for control of most

pigweeds, ragweed, and lambsquarters

• Sandea can suppress dayflower and control

spiny amaranth and common lambsquarters

Purple vs. yellow nutsedge

Purple vs. yellow nutsedge

Nutsedge control

• Can be suppressed (burned down) with

2,4-D or 2,4-D in combination with Evik

• Envoke, Sandea, and Yukon provide

excellent systemic control

Herbicide program: plant cane

• Fallow

– Start with clean, weed free field – 2 to 3

applications of glyphosate during the fallow

period

– Prior to planting, disk until soil is well worked

• Successive

– Multiple diskings until soil is well worked

Herbicide program: plant cane

• PRE

– Prowl + Atrazine

• Prowl = Prowl H20 : muck soils = up to 8.4 pts/acre;

otherwise 6.2 pts/acre)

– No POST activity; apply shortly after planting

– Will need to be incorporated into the soil (preferably by

rain or irrigation

• Atrazine 4L = 4-8 pts/acre/application

• Atrazine 90DF = 2.2-4.4 lbs/acre/application)

• POST

– Atrazine + 2,4-D (or Dicamba, or 2,4-D Dicamba mix)

Herbicide program: stubble cane

• PRE

– Prowl + Atrazine

• Prowl = Prowl H20 : muck soils = up to 8.4 pts/acre;

otherwise 6.2 pts/acre)

– No POST activity; apply shortly after harvest

– Will need to be incorporated into the soil (preferably by

rain or irrigation

• Atrazine 4L = 4-8 pts/acre/application

• Atrazine 90DF = 2.2-4.4 lbs/acre/application)

• POST

– Atrazine + 2,4-D (or Dicamba, or 2,4-D Dicamba mix)

Thank you