1 Trade nameManufacturerForm



3 ACTIVE INGREDIENTS: MCPA 125g/L + pyrasulfotole 25g/L+mefenpyr-diethyl

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



Group H herbicides - Pyrazole or phenyl pyrazole ketone
BalanceIsoxaflutole 750 g/kg (or480g/L)
Benzofenap 300Benzofenap 300g/L

Group I herbicides - Phenoxy
2,4-D amine 5002,4-D Amine 500g/L
2,4-D amine 6252,4-D Amine 625g/L
2,4-D amine plus Dicamba2,4-D 333g/L + dicamba 166g/L
2,4-D ester 8002,4-D Ester 800g/L
2,4-D ester plus Garlon2,4-D ester 530g/L + triclopyr 200g/L
2,4-D LV ester2,4-D LV ester 680g/L (or600)
2,4-DB 5002,4-DB 500g/L
2,4-DB plus MCPA2,4-DB 200g/L + MCPA 250g/L
AccessPicloram 120g/L + triclopyr 240g/L
Aminopyralid plus picloram gelAminopyralid 4.47g/L+picloram 44.7g/L
Dicamba 25 plus MCPA 150Dicamba 25g/L + MCPA 150g/L
Dicamba 500Dicamba 500g/L
Dicamba 700Dicamba 700g/kg (or 750 g/kg)
Dicamba plus MCPADicamba 80g/L + MCPA 340g/L
FallowBoss2,4-Dam 300g/L+Aminopyralid 7.5g/L+picloram 75g/L
Garlon 600Triclopyr 600g/L (or 755g/L)
Grazon ExtraAminopyralid 8g/L+picloram 100g/L+triclopyr 300g/L
HotshotAminopyralid salt 10g/L + fluroxypyr-meptyl 140g/L
LontrelClopyralid 300g/L
Lontrel 750Clopyralid 750g/kg
MCPA amineMCPA 500-750g/L
MCPA LVEMCPA LV ester 500g/L
MCPB 400MCPB 400g/L
PicloramPicloram 240g/L
Picloram plus TriclopyrPicloram 100g/L + triclopyr 300g/L
QuincloracQuinclorac 750g/kg (or180or200)
Starane 200Fluroxypyr 200-400g/L
Tordon 242MCPA 420g/L + picloram 26g/L
Tordon 75-D2,4-D 300g/L + picloram 75g/L
Tordon DSPicloram amine 100g/L + triclopyr amine 200g/L
Tordon RegrowthMasterAminopyralid 25g/L+picloram100g/L+triclopyr 200g/L
Tri-kombi24D Ester 800g/L + Dicamba 40g/L + Mecoprop 336g/L


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


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.


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.


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.


Hard water:
Salty water:
Tank life: Weeks.


Ally in tank mixes with Precept may have reduced growth rates and more discolouration.
Trace elements.
See HerbiGuide Compatibilities button.


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.


Ensure thorough coverage. Permit required.


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.
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 leave 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.


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.


Barley3 weeks on alkaline soil for 2 L/ha
Bean: Faba9 months + 250 mm rain on alkaline soil for 2 L/ha
Canola9 months + 250 mm rain on alkaline soil for 2 L/ha
Chickpea9 months + 250 mm rain on alkaline soil for 2 L/ha
Clover9 months + 250 mm rain on alkaline soil for 2 L/ha
LentilFollowing season + 250 mm rain on alkaline soil
Lucerne9 months + 250 mm rain on alkaline soil for 2 L/ha
Lupin9 months + 250 mm rain on alkaline soil for 2 L/ha
Maize8 weeks + 125 mm rain on alkaline soil for 2 L/ha
Oats3 weeks on alkaline soil for 2 L/ha
Pea: Field9 months + 250 mm rain on alkaline soil for 2 L/ha
Sorghum8 weeks + 125 mm rain on alkaline soil for 2 L/ha
Triticale3 weeks on alkaline soil for 2 L/ha
Vetch9 months + 250 mm rain on alkaline soil for 2 L/ha
VetchFollowing season + 250 mm rain on alkaline soil
Wheat3 weeks on alkaline soil for 2 L/ha
Replanting times are usually shorter on acid soils.


BarleyGrazing28 days
BarleyHarvestNot required
Cereal RyeGrazing14 days
Cereal RyeHarvestNot required
OatsGrazing14 days
OatsHarvestNot required
TriticaleGrazing14 days
TriticaleHarvestNot required
WheatGrazing14 days
WheatHarvestNot required


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


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.


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:

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


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:


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.


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.




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.


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. LC50 1.1 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 - LD50 113.3 g a.i./ha.
Aphidius rhopalosiphi: Pyrasulfotole - LD50 80.3 g a.i./ha
Accumulation: Does not accumulate in animal tissue.



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.


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.


See HerbiGuide Species Solution tab.


See HerbiGuide Species Solution tab.


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.


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
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)


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.



Bayer CropScience (2007). Precept technical guide.
Bayer (2007) MSDS May 2007.
Bayer (2008) Precept Label 60897/0108.


Collated by HerbiGuide. For more information see or phone 08 98444064.