Diclofop plus sethoxydim


3 ACTIVE INGREDIENTS: Diclofop-methyl 200g/L, sethoxydim 20 g/L plus mefenpyr-diethyl 20 g/L crop safener.

Formulation: Emulsifiable concentrate.


Fop or aryloxyphenoxypropionate and Dim or cyclohexanediones.


Fops and Dims. Tristar, Detonate, Fusilade, Hoegrass, Targa, Verdict, Sertin, Correct, Achieve, Select and Puma.


Decision is a selective and translocated post emergence herbicide that is absorbed mainly through leaves with some through the roots. The combination of a fop and dim group herbicide provides more effective control of ryegrass. The addition of a crop safener reduces the deleterious effects of sethoxydim on cereals. Its main use is for controlling Annual Ryegrass and some other grasses in wheat, barley, broadleaved crops and pastures. Toxicity to mammals and birds is low but it is toxic to fish. In land environments it presents few environmental hazards because of its low mobility in soil, low volatility, low toxicity and reasonably quick degradation in soil and water. Direct application to aquatic ecosystems should be avoided. Application to flood irrigated areas or similar may lead to contamination of water. Plants are likely to become resistant after repeated applications.


Best results when applied to young actively growing weeds in fine conditions.

Decision is normally applied in water with wetting agent as a post-emergence spray by boom sprays or aircraft. Spray oils such as Hasten, Uptake and DC-Trate improve Annual Ryegrass kill by 10% but may result in more crop retardation, however this rarely affects yield. Plants under drought stress are very difficult to kill with Decision. Ryegrass or wild oat plants in the two leaf stage are more susceptible to Decision than older or younger plants. Successful control has been achieved on dewy and frost covered crops but it is recommended to avoid these conditions if possible.

The addition of zinc (as zinc oxide or Twin Zinc) may reduce the crop retardation effects and doesn't appear to affect weed control.


Hard water




Trace elements.

Compatible with Twin Zinc.

Hormonal herbicides such as 2,4-D are antagonistic. 2,4-D decreases the conversion to the active form, decreases translocation of diclofop, increases the rate of detoxification and competes at the fatty acid synthesis level. Plants treated with 2,4-D up to two weeks before or after application may be less susceptible to application. MCPA antagonism is different and appears to be caused by reactions outside the plant.

Wetting agents improve the absorption of diclofop by plants. Spraying oils also improve the translocation of Decision which improves weed control but often reduces the crops tolerance.

Compatible with Hasten, Uptake, DC-Trate, BS1000.


Ryegrass and wild oats that are tolerant to diclofop occur naturally at low levels. After many annual applications of Decision a significant level of tolerance would be expected if no other form of weed control was practiced.


Maize10 weeks
Sorghum10 weeks
Rice10 weeks
Broad leaved plants0





Wear a face shield or goggles when handling the concentrate.

19 SOIL:


Decision is absorbed through the foliage and roots of nearly all plants. In susceptible plants it is converted to a biologically active form where it accumulates in the growing tips. Cell division and elongation are stopped resulting in the stunted appearance of treated plants. Membranes are disrupted giving a 'water soaked' appearance. Fatty acid synthesis is stopped resulting in the death of growing tips, hence leaves of treated grasses can be easily pulled from their sheaths. Plants tolerant to Decision appear to have a different fatty acid synthesis mechanism, degrade it more quickly and do not convert as much to the active form. It is normally, used as a post emergence herbicide but does have some pre emergence activity at high rates. Wild Oats and Annual Ryegrass germinating soon after spraying are often stunted.

Uptake and translocation:

Shoot uptake mainly with some root uptake. Translocated.

Physiological effects:

Yellowing, reddening, reduced root and shoot growth, death.

Residual Life and Breakdown:


Under good growing conditions the cereal biomass may be reduced for 2-3 weeks but the crop normally recovers by 6 weeks and yields are rarely reduced.


Annual ryegrass and wild oats stop growing soon after application. The leaves take on a water soaked or oily appearance within a few days. About a week later, leaves become red-brown in colour and may be easily pulled from their sheaths before dying. Plants that recover have severely reduced root systems.





Poison schedule - S6

Mammalian toxicity -

Acute oral LD50 (rats) - 512 mg/kg diclofop, 2676-3200 mg/kg sethoxydim, > 5000 mg/kg mefenpyr-diethyl. [For comparison table salt is 3000 mg/kg]

Acute dermal LD50 (rabbit) - >2000 mg/kg diclofop, > 5000 mg/kg sethoxydim, >4000 mg/kg mefenpyr-diethyl.

Skin - Active ingredients non irritating. Solvent is an irritant. Diclofop is sensitising is some tests.

Eye - Active ingredients non irritating. Solvent is an irritant.

Vapour inhalation - LC50 (rat) - > >1.36 mg/L air diclofop, >6.28 mg/L sethoxydim, >1.32 mg/L mefenpyr-diethyl.

Chronic oral toxicity NOEL - ppm for two years.

Not mutagenic or teratogenic (i.e. does not cause cancer or reproductive problems). Low quantities of naphthalene are present in the product which is classed as a potential human carcinogen.

Acceptable Daily Intake (ADI) -

Other Species -

Dangerous to fish and aquatic organisms.


Fish - High toxicity - LC50 - 0.24 mg/L for diclofop, 38-153 mg/L for sethoxydim, 2.4-4.2 mg/L for mefenpyr-diethyl.

Invertebrates - High toxicity - EC50 0.23 mg/L for diclofop, 1.5 mg/L for sethoxydim, 53 mg/L for mefenpyr-diethyl.

Algae - High toxicity - LD50 - 1.5-5.8 mg/L for diclofop, 1.65 mg/L for mefenpyr diethyl.

Bees - Low toxicity for all active ingredients.

Earthworms - Low toxicity for all active ingredients.

Birds - Low toxicity for all active ingredients.


Irritation of eyes and respiratory tract.

Headache, dizziness, nausea, drowsiness, confusion, anaesthesia.

May cause lung damage if swallowed.


If SWALLOWED - Rinse mouth with water. Do NOT induce vomiting. Give a glass of water if patient is fully conscious.

If in EYES - Irrigate with plenty of water. See a doctor.

If on SKIN - Rinse with plenty of water, remove contaminated clothing, wash with soap and water.

If INHALED - Remove patient to fresh air. Apply artificial respiration if breathing stops. See a doctor.

Advice to doctor - Treat symptomatically.


The diclofop component of Decision is strongly adsorbed on soils. Its solubility provides a slight risk for movement into ground water under extreme conditions. It is broken down in plants. In soil, microbes break down diclofop with a half life of 1-57 days. At higher pH and under anaerobic conditions the half life is increased. Diclofop is rapidly excreted from animals and does not move into milk or eggs. It is not degraded by light.

The sethoxydim component is readily degraded.

Mefenpyr-diethyl hydrolyses with a half life >365 days at pH 5, 40 days at pH 7 and 0.35 days at pH 9. It photo degrades with a half life of 2.9 days. In soil it has a half life of less than 10 days and is not leachable.

It has a half life in soil of 1-57 days.

It has an EPA classification for soil mobility that ranges from

Ground water contamination is unlikely in all but extreme conditions.

Accumulation in milk and tissues - undetectable.


Water solubility at 25 C. - Emulsifies in water;

Oil solubility -

Octanol:Water ratio at 25 C. - Kow Log P = 4.5 for diclofop. Kow Log P = 4.51 for sethoxydim at pH 5 and 1.67 at pH 7. Kow Log P = 3.83 for Mefenpyr-diethyl at pH 6.3 and 21 C.;

Vapour Pressure at 38 C. - 0.3 kPa for solvent.

Vapour density - > 1.0 for solvent.

Dissociation constant - pKa

Melting point - C.

Boiling point - 179-213 C.

Molecular weight -

Half life in water - days at pH5 and 35 C.

pH - 5-6 in 1% solution.

Specific Gravity - 0.997

Flashpoint - >63 C

Autoignition - >400 C.


Ashton, F.M. and Crafts, A.S. (1981) Mode of Action of Herbicides. (Wiley-Interscience publication).

Kearney, P.C. and Kaufman, D.D. (1976). Herbicides. Chemistry, degradation and mode of action. Vol 1 & 2.

Bayer (2003) MSDS and Label 56166/0603.

Field Crop Herbicide Information:


2. Concentration of Active Constituent : g/kg

Trade Name : Decision.

3. Formulation : Emulsifiable concentrate.

4. Poison Schedule : 6

6. Product colour : Clear amber liquid.

Odour : Aromatic hydrocarbon.

7. Product Flammability : Combustible liquid.

8. Dangerous Goods Class : Not a dangerous good.

9. Shelf Life : 3 years.

10. Mixtures Compatibility :

11. Registered Crop(s) :

12. Effect of Soil Texture on Herbicide : No specific effect.

13. Effect of Soil pH on Herbicide : No effect unless it affects plant growth.

14. Effect of Soil Organic Matter on Herbicide : No effect unless it affects plant growth.

15. Mode of Action : Foliar translocation, some contact and root absorption. Post-emergent.

16. Application Timing :

17. Rate Variations :

18. Rates Selection :

19. Weeds Controlled :

20. Effect on Crop : Wheat - crop yellowing may occur in some seasons.

21. Effect on Legume Species : Not affected.

22. Soil Moisture at Application :

DRY - If weeds are stressed expect lower efficacy.

MOIST - Should result in good control.

WATERLOGGED - If weeds are stressed expect lower efficacy.

23. Frost Effects : Extended frost periods will reduce weed vigour and therefore weed control. Frosts during and after application have only had minor effects on weed control but should be avoided if possible.

24. Frost Free Days Required After Application : Nil.

25. Effect of Application Water Quality on Herbicide :

Saline Water - No effect.

Soil Colloids - No effect.

26. Recommended Water Volume : 50 - 150 L/ha boom, 20 - 30 L/ha aircraft.

27. Nozzle Type : Flat fan wide angle (11001 to 11003 or equivalent) for boom sprays.

28. Recommended Nozzle Pressure : 280 - 300 kPa (40.6 - 43.5 psi). Use small droplets (200 - 300 micron) and aim for a droplet density of approximately 25 - 50 droplets /cm2.

Air induction nozzles are not recommended.

29. Recommended Filter Size : Mesh size as suitable for nozzle being used.

30. Recommended Wetter - Hasten or crop oil. Wetting agent when tank mixed.

31. Other Additives :

32. Rain Fastness : Minimum 2 hours.

33. Time Interval Before Effect is Noticed : 7 - 10 days, depending on temperature.

34. Weed Symptoms : Affected plants show yellowish/reddish patches. After 10 - 14 days, plants can be easily pulled from the ground due to cessation of root growth.

35. Effect of Herbicide/Disease Interaction on Crop :

36. Withholding Period :

Harvest - Not required when used as directed.

Grazing - 7 weeks.

37. Plant-Back Period :

Maize, Sorghum, Rice 10 weeks.

Broadleaf plants Nil.

38. Spray Tank Clean-Up : Drain tank and flush with clean water and detergent for a minimum of 10 minutes. Fill the tank with clean water and flush for 15 minutes. Remove the nozzles and screens and clean separately.

39. Other Comments : Export tolerances and MRL's may not be established in some export markets. Check with Bayer before use on export crops.


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