Ragweed Parthenium Control Programs in South Florida

Calvin Odero

Tropical Research & Education Center

Homestead, FL

Weed Science Research at EREC

• Crops

‒ Sugarcane

‒ Vegetables

‒ Bioenergy crops

‒ Rice

South Florida Sugarcane Region

Miami

West PalmBeach

Total Sugarcane Acreage

2010-2011

389,616 acres

Organic Soils

319,553 acres82 %

Sandy Soils

70,063 acres18 %

Non-crop areas

Common ragweed

Ragweed parthenium

Ragweed parthenium

Ragweed parthenium

(Parthenium hysterophorus)

Synonyms• False ragweed• Santa Maria feverfew

Asteraceae

Native• Central America• West Indies• South America

Distribution of parthenium

Biology and life cycle

Erect-branched annual, grow, flower throughout the year in subtropical environs

Predominantly germinate in spring, early summer• Flower 4 to 8 wks after germination,1-3 ft tall

Prolific seed producer capable of producing 19,000 seeds/ft2 • Soil seedbank quantities of 4,200 seeds/ft2

Buried seeds remain viable in soil for >2 yrs • Build-up a substantial, persistent seedbank• Viable for only 6 months on surface

Seedling

Cotyledons • Rounded paddle shape, 0.1

to 0.2-in long, borne on short stalks <1-in long

1st true leaves• Egg-shaped, covered in

fine, white hairs

Older leaves • Lobed, deeply divided

Seedling • Basal rosette • Leaves 3 to 8-in long,1 to 2-

in wide• Hairy (leaves, stems)

Mature plant

Stems • Erect, hairy• Branched, covered by

longitudinal lines

Leaves • Alternate, deeply

lobed• Lower leaves form a

basal rosette, upper leaves can be entirely or slightly lobed

• Hairy

Mature plant

Flower heads • Clusters at the top of plant,

borne on short stalks, arise from the leaf forks

• Densely haired small, white, form a 5-side disk shape

• Long white flowerlets (ray flowers) present in the corners

• Flower heads become hard and brown as they mature

Seeds • < 0.1-in long, flattened,

narrow-diamond shape• Striped grey to black

Deep taproot

Negative impacts

Rapid invader that reduces biodiversity, affects landscape, soil qualityAllelopathic (parthenin)• Tree spp, crops, weed spp

Yield reduction• Sorghum (49-97%)

Harmful to humans, livestock• Contact dermatitis, skin irritation, nausea,

giddiness, respiratory problems (bronchitis, asthma)• Ingestion by livestock results in acute toxicity

Parthenium control in EAA

Frequency of detection of parthenium is on the rise in recent years in the EAA• Ditch banks, cultivated fields, noncropland

Increase can be attributed to• Repeated use of glyphosate over the years which

has imposed unprecedented selection pressure on weed populations − Shifts in weed species from those easily controlled by

glyphosate to those more tolerant − Glyphosate resistance?

• Lack of POST herbicides with residual activity

Saflufenacil

Trade name: Sharpen

Preplant, PPI, PRE burndown, POST harvest aid• Corn, small grains, fallow, legumes

Pyrimidinedione• Protoporphyrinogen-IX-oxidase (PPO)

− Chlorophyll biosynthesis

• PPO inhibition results in a rapid loss of membrane integrity− Cellular leakage, tissue necrosis, plant death

• Readily absorbed by roots, shoots, leaves− Translocated via the xylem, relatively little movement in the phloem

• Contact and residual activity− Show initial injury symptoms within a few hours

25 g ai/ha (1 fl oz/A) saflufenacil treated parthenium 1 DAT

Saflufenacil

Broad-spectrum control of broadleaf weeds• More tolerant/resistant to glyphosate

− Common lambsquarters, Russian thistle, waterhemp, common and giant ragweed

Parthenium difficult to control with glyphosate• Can saflufenacil be a control option for

parthenium in the EAA?

Objective

Compare the response of parthenium to POST application of saflufenacil in the EAA

Methods

Greenhouse experiments at EREC

CRD• Saflufenacil

− 0, 0.8, 1.6, 3.1, 6.3, 12.5, 25, 50 g ai/ha

• Glyphosate− 0, 26, 53, 105, 210, 420, 840, 1680 g ae/ha

POST application• Rosette stage of parthenium

Treatments applied with a CO2 pressurized knapsack sprayer• 8002, 180 L/ha, 276 kPa

Methods

Parthenium injury visually estimated at 7 and 14 DAT, scale of 0 to100 where 0 = no injury

100 = complete plant death

Parthenium harvested at soil level at 14 DAT to determine biomass

Parthenium survival (regrowth) following herbicide treatment recorded at 14 DAT

Methods

• Nonlinear regression performed to quantify effect of herbicide rate on − Visual injury, dry weight, survival

• drc package of R

Left to right: 0, 26, 53, 105, 210, 420, 840, 1680, 0 g ai/ha saflufenacil

treated plants at 7 DAT

Saflufenacil: Injury (7, 14 DAT)

ED90 = 18.9 g ai/ha (7 DAT) ED90 = 8.0 g ai/ha (14 DAT)

Saflufenacil: dry weight

GR90 = 8.9 g ai/ha

Saflufenacil: probability of survival

Glyphosate: dry weight

Left to right: 0, 26, 53, 105, 210, 420, 840, and 1680 g ae/ha glyphosate treated plants at 7 DAT

Field experiment

In 2010 and 2011 at the EREC, King Ranch near Belle Glade

RCBD, 4 reps• Saflufenacil (6.2, 12.5, 25, 50 g ai/ha)• Glyphosate (840, 1680 g ae/ha)

Parthenium injury visually estimated at 7, 14, 21 DAT, scale of 0 to100 where 0 = no injury

100 = complete plant death

Field: Control

ED90 = 27.0 g ai/ha (7 DAT) ED90 = 6.2 g ai/ha (14 DAT)ED90 = 5.7 g ai/ha (21 DAT)

1 DAT (12.5 g ai/ha)

7 DAT (12.5 g ai/ha)

Discussion

Parthenium control increased as rates of saflufenacil increased• Greenhouse: ED90 of 18.9 and 8.0 g ai/ha at 7 and 14 DAT

• Field: ED90 of 27.0, 6.2, and 5.7 g ai/ha at 7, 14, and 21 DAT

Parthenium dry weight decreased as rates of saflufenacil increased • GR90 of 8.9 g ai/ha

Probability of rosette ragweed survival decreased with increasing rates of saflufenacil

No response of parthenium to glyphosate even at 1680 g ae/ha (43 fl oz/A ~2.5 pt/A)

Conclusion

Saflufenacil can be applied as a POST burndown for control of parthenium

ED90 values from 14 DAT indicated that saflufenacil can provide 90% control of ragweed parthenium at 5.7 to 8.0 g ai/ha (<0.5 fl oz/A)• Lower than the saflufenacil recommended POST burn-down

− 25 to 50 g ai/ha (1 to 2 fl oz/A) for fallow areas− 2 to 4 fl oz/A (<6-in weeds) for noncropland− 4 to 6 fl oz/A (>6-in weeds) for noncropland

Saflufenacil plus other herbicides can provide residual control of parthenium and other broadleaf weeds• Eliminate the need for repeated herbicide application by

saving the grower both time and additional application cost

Other herbicides for control

PreemergenceAlachlor (Lasso)

Atrazine

Chlorimuron (Classic)

Flumioxazin (Valor)

Postemergence• 2,4-D amine• 2,4-D plus atrazine• Bentazon (Basagran)• Dicamba (Banvel)• Diquat (Reward)• Acifluorfen (Blazer) PPO soybean• Glufosinate (Liberty)• Metsulfuron (Escort)• Halosulfuron (Sandea)• Metribuzin (Dimetric)• Picloram (Tordon)• Trifloxusylfuron (Envoke)

Literature sources

EDISOdero, D.C., B. A. Sellers, and J.A. Ferrell. Biology and Control of Ragweed Parthenium in Non-Cropland.

Stamps, R. H. Identification, Impacts, and Control of Ragweed Parthenium (Parthenium hysterophorus L.)

Odero, D. C. Response of ragweed parthenium (Parthenium hysterophorus) to saflufenacil and glyphosate. Weed Technology. In press.

Contact information

Calvin Odero

Phone: 561-993-1509

Email: dcodero@ufl.edu

http://erec.ifas.ufl.edu/weeds/

THANKS

QUESTIONS?