Precept

Precept

1 Trade name	Manufacturer	Form
PRECEPT SELECTIVE HERBICIDE	BAYER CROPSCIENCE PTY LTD	EC

2 PRICE:

$14.16

3 ACTIVE INGREDIENTS:

MCPA 125g/L + pyrasulfotole 25g/L+mefenpyr-diethyl

MCPA is present as the 2-ethylhexyl ester - a low volatile ester.

4 CHEMICAL GROUP: H,I

5 RELATED HERBICIDES:

Group H herbicides - Phenoxy

Balance	Isoxaflutole 750 g/kg
Benzofenap 300	Benzofenap 300g/L

Group I herbicides - Pyrazole or phenyl pyrazole ketone 2,4-D amine 500	2,4-D Amine 500g/L
2,4-D amine 625	2,4-D Amine 625g/L
2,4-D amine plus Dicamba	2,4-D 250gL + dicamba 100g/L
2,4-D ester 800	2,4-D Ester 800g/L
2,4-D ester plus Garlon	2,4-D ester 530g/L + triclopyr 200g/L
2,4-D LV ester 600	2,4-D LV ester 600g/L
2,4-DB 400	2,4-DB 400g/L
2,4-DB plus MCPA	2,4-DB 200g/L + MCPA 250g/L
Access	Picloram 120g/L + triclopyr 240g/L
Dicamba 200	Dicamba 200
Dicamba 25 plus MCPA 150	Dicamba 25g/L + MCPA 150g/L
Dicamba 500	Dicamba 500g/L
Dicamba 700	Dicamba 700g/kg
Dicamba plus MCPA	Dicamba 80g/L + MCPA 340g/L
Garlon 600	Triclopyr 600g/L
Grazon Extra	Aminopyralid 8g/L+picloram 100g/L+tricolpyr 300g/L
Hotshot	Aminopyralid salt 10g/L + fluroxypyr-meptyl 140g/L
Lontrel	Clopyralid 300g/L
Lontrel 750	Clopyralid 750g/kg
MCPA amine 500	MCPA 500g/L
MCPA LVE	MCPA LV ester 500g/L
MCPB 400	MCPB 400g/L
Picloram plus Triclopyr	Picloram 100g/L + triclopyr 300g/L
Starane 200	Fluroxypyr 200g/L
Tordon 242	MCPA 420g/L + picloram 26g/L
Tordon 75-D	2,4-D 300g/L + picloram 75g/L
Tri-kombi	24D Ester 800g/L + Dicmaba 40g/L + Mecoprop 336g/L

6 GENERAL DESCRIPTION:

Precept is a post emergence, leaf absorbed, translocated herbicide for broad leaved weed control in cereals.

7 APPLICATION METHODS AND TIPS:

Best results when plants are actively growing in warm weather with good light intensity. Apply at least one hour before sunset if low night temperatures are expected.

Use 1% spray oil or ammonium sulphate at 1%. Wetting agents if mixing with Wildcat.

Avoid spraying frost affected plants or use higher rates.

Ensure good coverage.

Use higher water volumes on dense or old weeds.

8 WEATHER:

Rainfast in 2 hours.

Frost effects: Less effective on frost affected plants or when used in frosty conditions. Use higher rates and apply at least an hour before sunset or preferably during the warmest part of the day.

Wind: Avoid application when wind speeds are less than 1 km/hour if susceptible crops are within 1 km. Avoid application if wind speeds are greater than 20 km/hour and susceptible crops are within 200 metres.

Inversions: Don't apply during inversion conditions.

Temperature: Best results in warm temperatures. Poorer results when temperatures are less than 4 degrees C.

Delta T and relative humidity: Avoid application when Delta T is greater than

Soil moisture at application: Best results when adequate soil moisture allows active growth. Poorer results under water-logged or dry conditions that are reducing plant growth rate.

9 ADJUVANTS:

Wetting agents: Are often used where a mixing partner makes the use of a spray oil undesirable.

Spray oils: Generally applied with a spray oil at 1% when applying Precept alone.

Ammonium sulphate: Is often used when applying Precept alone. Use at 500 g a.i./ha or 1% of spray mix.

See label for specific adjuvant recommendations.

10 WATER QUALITY:

Hard water:

Salty water:

Colloids:

pH:

Tank life: Weeks.

11 COMPATIBILITY:

Ally in tank mixes with Precept may have reduced growth rates and more discolouration.

Trace elements.

See HerbiGuide Compatibilities button.

12 EQUIPMENT:

Boom sprays:

Carrier volume: 50-150 L/ha. Use smaller nozzles if low rates are being used. Use higher water rates on larger or overlapping weeds.

Nozzles: Flat fan. Use a fine/medium (200-300 micron VMD) or medium droplet size.

Pressure: 150-400 kPa.

Use equipment that provides constant agitation.

Aerial:

Ensure thorough coverage. Permit required.

13 SPRAYER DECONTAMINATION:

Clean Up:

Clean soon after spraying to reduce the risk of forming dried deposits that may be difficult to remove.

Remove filters and clean separately. Rinse with soapy water (eg 500 mL or g of Drive, Dynamo, Omo or Surf per 100 L water) or water plus 0.25% wetting agent and run through boom. Rinse with water.

Decontamination:

Remove filters and clean then soak in 500 mL household ammonia in 10 L water for 30 minutes.

Rinse sprayer with soapy water (eg 500 mL or g of Drive, Dynamo, Omo or Surf per 100 L water) or water plus 0.25% wetting agent and run through boom. Fill with 1% solution of ammonia and allow to stand for several hours. Triple rinse with water. Or use a commercial spray tank and equipment cleaner.

Rinse nozzles and filters in water and replace.

Don't use chlorine based cleaners.

14 HERBICIDE RESISTANCE:

Tolerant plants are expected to occur and may dominate the weed population after repeated applications. No resistant populations had been reported by 2008.

Controls group B and Group F resistant weeds. Pyrasulfotole is effective on group I (hormone) resistant weeds.

15 REPLANTING INTERVALS:

Crop	Time
Barley	3 weeks on alkaline soil for 2 L/ha
Bean: Faba	9 months + 250 mm rain on alkaline soil for 2 L/ha
Canola	9 months + 250 mm rain on alkaline soil for 2 L/ha
Chickpea	9 months + 250 mm rain on alkaline soil for 2 L/ha
Clover	9 months + 250 mm rain on alkaline soil for 2 L/ha
Lentil	Following season + 250 mm rain on alkaline soil
Lucerne	9 months + 250 mm rain on alkaline soil for 2 L/ha
Lupin	9 months + 250 mm rain on alkaline soil for 2 L/ha
Maize	8 weeks + 125 mm rain on alkaline soil for 2 L/ha
Oats	3 weeks on alkaline soil for 2 L/ha
Pea: Field	9 months + 250 mm rain on alkaline soil for 2 L/ha
Sorghum	8 weeks + 125 mm rain on alkaline soil for 2 L/ha
Triticale	3 weeks on alkaline soil for 2 L/ha
Vetch	9 months + 250 mm rain on alkaline soil for 2 L/ha
Vetch	Following season + 250 mm rain on alkaline soil
Wheat	3 weeks on alkaline soil for 2 L/ha

Replanting times are usually shorter on acid soils.

16 WITHHOLDING PERIODS:

Crop	Type	Time
Barley	Grazing	28 days
Barley	Harvest	Not required
Cereal Rye	Grazing	14 days
Cereal Rye	Harvest	Not required
Oats	Grazing	14 days
Oats	Harvest	Not required
Triticale	Grazing	14 days
Triticale	Harvest	Not required
Wheat	Grazing	14 days
Wheat	Harvest	Not required

17 RE-ENTRY PERIOD:

No adverse effects expected but it is good practice to wear protective clothing if in contact with the crop before the spray has dried.

18 PROTECTIVE CLOTHING:

Overalls, boots and washable hat. Use gloves and face shield when handling the concentrate.

19 SOIL:

Not recommended for use on soils with a pH > 8.4.

Pyrasulfotole persists longer in alkaline soils. Otherwise soil type has little direct influence.

20 MODE OF ACTION:

Pyrasulfotole is a HPPD inhibitor that affects 3 biochemical pathways.

Uptake and translocation:

Absorbed rapidly through foliage and transported in the phloem and xylem. Minor root uptake may occur.

Physiological effects:

Pyrasulfotole

It interferes with the energy transfer process by inhibiting the biosynthesis of plastoquinones.

It reduces vitamin E production by inhibiting tocopherol production. Vitamin E acts as an antioxidant which protects the cell membranes from free radicals and oxidative stress.

It prevents carotenoid synthesis. Carotene protects chlorophyll from ultra violet damage so the plant turns white or bleaches after spraying.

MCPA

Is readily absorbed and concentrates at the growing points (meristems) where it mimics plant hormones interfering with protein synthesis, cell division and growth.

21 SELECTIVITY:

Crop tolerance:

Crops physically damaged by hail, wind, sand blast or insects may be adversely affected by Precept.

Metabolically degraded by tolerant species. The crop safener (mefenpyr-diethyl) in the formulation increases selectivity.

Hay yield may be decreased due to crop shortening especially on boom overlaps.

Varietal sensitivities:

Barley is less tolerant than other cereals. Apply from the 3 leaf (Z13) stage (5 leaf for barley) to the first node (Z31) stage.

Effect on Clover Species:

Damages clover (70% kill at 1L/ha)

Effect on Medic Species:

Damages medics (60-90% kill at 1 L/ha)

Effect on Lucerne:

Damages seedling Lucerne.

Effect on Native Plants:

22 DISEASE AND INSECT EFFECTS:

Crop growth may be reduced and discolouration increased in crops affected by root diseases such as Take-All, Rhizoctonia and Cereal Cyst Nematode.

Crops physically damaged by insects may be adversely affected by Precept.

23 PLANT SYMPTOMS:

Susceptible plants stop growing about 5-10 days after spraying and the leaf margins turn yellow. Yellow patches on leaves usually appear in 2-3 weeks and the growing tips turn white. Tissue death usually occurs within 6 weeks. The timing of symptom development is faster in warmer weather.

SECONDARY EFFECTS:

24 TOXICITY:

Summary:

Low mammalian toxicity. Severe eye irritant. Highly toxic to algae and aquatic organisms.

Irritating to skin, Risk of serious eye damage. May cause lung damage if swallowed.

Details:

Poison schedule: S5.

Mammalian toxicity:

Acute oral LD50: >5000 mg product/kg (rat), [For comparison table salt is 3000 mg/kg]

Acute dermal LD50: > 2000 mg product/kg (rat).

Skin: Irritant. Not a skin sensitiser.

Eye: Severe irritant

Vapour inhalation: LC50 > 4.345 mg product/L air [>4345 mg/m3] (rat).

Chronic oral toxicity: NOEL mg/kg for two years.

MCPA was not carcinogenic, mutagenic or teratogenic in animal studies (i.e. does not cause cancer or reproductive problems in animal tests).

Pyrasulfotole was not mutagenic or teratogenic in animal studies. It had a possible carcinogenic effect at high doses in animals but is not expected to be carcinogenic in humans. Naphthalene is a possible human carcinogen (group 2b).

Acceptable Daily Intake (ADI):

In rats, pyrasulfotole is rapidly absorbed and distributed. Up to 95% is excreted intact mainly in the urine. Residues are occasionally detected in offal.

Other Species:

Birds: Pyrasulfotole - Very low toxicity. LD50 >2000 mg a.i./kg (Bobwhite quail)

MCPA EHE - Moderately toxic. LD50 = 270 mg/kg (Bobwhite quail)

Fish: Pyrasulfotole - Low toxicity LC₅₀ >100 mg a.i./L (96 hr).

MCPA EHE - Toxic. LC₅₀= 32. mg/L.

Invertebrates: Pyrasulfotole - Low toxicity. Daphnia magna EC₅₀ >100 mg a.i./L (48 hr). MCPA EHE - Low toxicity. Daphnia magna EC₅₀ >190 mg/L (48 hr).

Oyster: Pyrasulfotole - Low toxicity. EC₅₀ >100 mg a.i./L (96 hr).

Mysid Shrimp: Pyrasulfotole - Low toxicity. LC₅₀1.1 mg a.i./L (96 hr).

Bees: Pyrasulfotole - Low toxicity. Oral LD₅₀>119.56 ug a.i./bee (72 hr). Contact LD₅₀ >75 ug a.i./bee (72 hr).

Arthropods: toxicity.

Earthworms: Pyrasulfotole - Low toxicity. LC₅₀ >1000 mg a.i./kg.

Algae: Pyrasulfotole - Moderate toxicity. Selenastrum EC₅₀ 11.6 mg a.i./L (96 hr). NOEC 2.6 mg a.i./L. LOEC 6.4 mg a.i./L. Pseudokirchneriella subcapitata EC₅₀ 11.6 mg a.i./L (96 hr).

MCPA EHE - Low toxicity. EC₅₀= 57 mg/L.

Lemma gibba: Pyrasulfotole - Low toxicity. EC₅₀ 30.2 ug a.i./L (7 day).

Typhlodromus pyri: Pyrasulfotole - LD₅₀113.3 g a.i./ha.

Aphidius rhopalosiphi: Pyrasulfotole - LD₅₀ 80.3 g a.i./ha

Accumulation: Does not accumulate in animal tissue.

25 TOXICITY SYMPTOMS:

26 FIRST AID:

If SWALLOWED: Rinse mouth with water. Give a glass of water to sip. Do NOT give anything by mouth to a semiconscious or unconscious patient.

If in EYES: Irrigate with plenty of water. See a doctor immediately as serious eye damage can occur.

If on SKIN: Rinse with plenty of water, remove contaminated clothing, wash with soap and water. See a doctor if symptoms persist.

If INHALED: Remove patient to fresh air. If breathing stops then apply artificial respiration and see a doctor.

Advice to doctor: Treat symptomatically.

Contact the Poisons Information Centre on 131126.

27 ENVIRONMENTAL FATE:

Half life in soil: Pyrasulfotole 11-72 days. Dissipation half lives in soil are 7-31 days. Degradation is mainly by aerobic microbes.

MCPA 7-41 days depending on pH, moisture and organic matter.

Half life in water: MCPA 35 days in sterile water at pH and C. It is less in water where microbes are present.

It has an EPA classification for soil mobility that ranges from

There some movement of Pyrasulfotole residues in soils.

Ground water contamination

Accumulation in milk and tissues.

pH stability:

Photolysis rate: Pyrasulfotole and MCPA is relatively resistant to UV breakdown.

Hydrolysis half life: Pyrasulfotole - long.

Biodegradation rate: Pyrasulfotole is not readily biodegradable.

MCPA EHE has a low potential for bio accumulation.

MCPA EHE is fairly mobile in soils but it degrades quickly in aerobic soils and water.

Residual Life and Breakdown:

Precept does not provide reliable control of plants before emergence.

Pyrasulfotole breaks down rapidly in cereals and tolerant plants. No residues were found in wheat and barley grain. Residues in oat grain were around 0.1 mg/kg. In soil it is broken down mainly by soil micro organisms. It has moderate soil absorption. It is stable in water and dissipates onto sediments where it is bound.

MCPA is actively broken down in plants and rapidly degraded by soil micro organisms.

28 REGISTERED CROPS:

See HerbiGuide Species Solution tab.

29 REGISTERED WEEDS:

See HerbiGuide Species Solution tab.

30 REGULATION AND LEGAL:

UN number: Not applicable.

CAS numbers: MCPA 294-50-1. Pyrasulfotole 365400-11-9. Mefenpyr-diethyl 135590-91-9. Hydrocarbon solvent 64742-94-8-5. Naphthalene 91-20-3.

Hazchem code: Not applicable.

NOHSC classification: Hazardous.

Land transport:

Dangerous goods class (ADG): Not classified as a dangerous good

Sea transport:

Proper shipping name: Not applicable.

International Maritime Dangerous Goods Code (IMDG):

Class: Not applicable.

Packaging group: Not applicable.

EPG: Not applicable.

Not a marine pollutant.

31 PROPERTIES:

Colour: Clear amber to dark brown liquid.

Odour: Slight naphthalene odour.

Form: Liquid.

Chemical name: MCPA - 4-chloro-2-methyl phenoxy acetic acid plus Pyrasulfotole - (5-hydroxy-1,3-dimethylpyrazole-4-yl)(2-mesyl-4 trifluoromethylphenyl)methanone

IUPAC

CAS

Empirical formula:

Water solubility: Emulsifies in water.

Oil solubility:

Octanol:Water ratio: MCPA LogPow = 0.71 at 25 C at pH 7 ;

Pyrasulfotole LogPow = 1.36 at 23 C at pH 7 ;

Soil organic carbon absorption coefficient (Koc):

Vapour Pressure: 0.03 kPa at 38 C due to hydrocarbon solvent.

Vapour density: >1.

Dissociation constant: pKa

Melting point: C.

Boiling point: 220-290 C - hydrocarbon solvent.

Molecular weight:

Bulk density: 1.05 g/mL at 20 C.

Specific gravity: 1.047-1.057 g/cm³ at 20⁰C.

pH: 3-5 (1% emulsion)

Flammability: Not flammable. Combustible. Not explosive.

Flashpoint: 96 C. L.E.L = 0.6. U.E.L = 7% vol in air for solvent.

Autoignition: >450 C - hydrocarbon solvent.

Corrosivity: Mildly corrosive to steel.

Shelf Life: years.

(When Stored under Ideal Conditions)

32 SPILLS:

Extinguish possible sources of ignition.

Absorb spill with earth, sand, clay or absorbent material.

Ventilate area after cleanup.

33 FIRE:

Extinguish with water spray, foam, carbon dioxide or dry agent.

Toxic fumes may be released in fire. Wear breathing apparatus or avoid smoke.

34 COMMENTS:

35 REFERENCES:

Bayer CropScience (2007). Precept technical guide.

Bayer (2007) MSDS May 2007.

Bayer (2008) Precept Label 60897/0108.

Acknowledgments:

Collated by HerbiGuide. For more information see www.herbiguide.com.au or phone 08 98444064.