Metsulfuron 200 plus Picloram 240

3 ACTIVE INGREDIENTS: Metsulfuron-methyl 200 g/kg + Picloram potassium salt 240 g/L

Formulation: 2 part pack - metsulfuron is a water dispersible granule and picloram is an aqueous concentrate.

The picloram component is a salt with low volatility making it safer to use close to hormone sensitive crops.

The data below is for the two components - metsulfuron followed by picloram.

Metsulfuron component

4 CHEMICAL GROUP: B - Herbicide.


5 RELATED HERBICIDES: Glean, Siege, Logran.


Metsulfuron is an extremely potent herbicide on some annual and perennial broad-leaved species.

It is a selective, translocated herbicide that is mainly absorbed through leaves though root absorption can occur. Its main uses are for broad-leaved weed (especially sorrel) control in cereals, as a tank mix with glyphosate for pre-plant weed control and for the control of perennial weeds such as bracken and blackberry. It is of low toxicity to mammals, birds and fish. Metsulfuron acts on the ALS enzyme in plants which is not present in animals and this is the main reason for its low toxicity. It presents little hazard in the environment because of its low rates of use, low toxicity and quick degradation in field situations.


Metsulfuron is usually applied in water as a broadcast application through hydraulic nozzles or as a directed spray using hand held equipment. It can be applied in ultra low volumes of carrier.

It is commonly mixed with other herbicides.

Surfactants often increase weed control but should not be used when metsulfuron is tank mixed with other herbicides for selective weed control in crops.

Under stressed conditions weeds become more tolerant and crops less tolerant to metsulfuron. For each 10 degree drop in temperature the crops ability to break down metsulfuron drops by a factor of 2 to 5, thus under cold conditions crop damage is more likely.


Non-ionic surfactants and crop oils increase absorption.

Metsulfuron is generally antagonistic with the grass herbicides. It is synergistic with chlorsulfuron and possibly with the hormonal herbicides and glyphosate. It is incompatible with most trace elements and ammonium sulphate.


Plant populations tolerant to metsulfuron are expected to occur naturally after repeated applications of herbicides from the sulfonylurea group.


Metsulfuron is absorbed by leaves and translocated to growing points of the plant where it stops cell division. Tolerant species, such as wheat and barley, degrade metsulfuron (by hydroxylation of the phenyl ring then conjugation with sugars) much faster than do sensitive species. Degradation products are non toxic and herbicidally inactive. Secondary effects on photosynthesis account for the yellowing of treated plants.

It does not normally affect seed germination.


Crop tolerance:

Varietal sensitivities:

Wheat - Amery, Brookton, Calingiri and Kulin are sensitive.

Effect on Clover Species:

Effect on Medic Species:

Effect on Lucerne:

Effect on Native Plants:



Growth stops as soon as metsulfuron is translocated to the growing points. In perennial species this may be many months after treatment and new growth may start elongating before dying at the tip. Death then progresses from the tip back to the base of the plant. In annual weeds, growth stops soon after spraying. The leaves turn yellow or red from 1 to 3 weeks after spraying and death follows, 1 to 2 weeks later.


Metsulfuron and residues in the soil from previous applications may make the crop more susceptible to Take-All, CCN, Rhizoctonia and zinc, copper and manganese deficiency (Hollaway, 1997).

It has no impact on N or P nutrition of cereals (Wilhelm et al, 1995).


Mammalian toxicity - low.

Acute oral LD50 - > 5000 mg/kg (rat)

Acute dermal LD50 - > 2000 mg/kg (rabbit).

Skin - mildly irritating.

Eye - mildly to not irritating.

Vapour inhalation - LC50 > 5 mg/L air (rat).

Chronic oral toxicity - Low. NOEL 50 mg/kg for 2 years (rat).

Birds - low toxicity. LD50 mallard ducks > 2000 mg/kg and bobwhite quail > 5000 mg/kg diet.

Fish - low toxicity. LC50 rainbow trout and bluegill > 150 mg/L.

Invertebrates - low toxicity. LC50(48 hour) Daphnia > 150 mg/L. 21 day NOEL for survival and breeding > 150 mg/L.

Bees - low toxicity. LD50 > 25 ug/bee.

Earthworms - low toxicity. LC50 > 1000 mg/kg soil.


Metsulfuron does not usually cause any symptoms because of its low toxicity.

May irritate skin.


Metsulfuron is broken down in the soil mainly by microbes and hydrolysis. The half life is usually in the range of 1 week to 1 month depending on soil conditions. (6.2 to 180 days in US studies). Degradation is quickest in warm, moist, acid soils with a high organic matter. Little is naturally degraded due to exposure to sunlight and volatilisation. In water there is degradation by hydrolysis. It is non-volatile, but will move through the soil profile with the water flow. On the EPA classification it ranges from mobile to intermediate mobility depending on the soil type. Mobility usually increases with increasing soil pH and decreasing organic matter. Despite its mobility it is not expected to cause problems in the environment because of its low rates of use, quick degradation and low toxicity. Very little leaching below the surface horizon of soils has been found. In animals the majority of metsulfuron ingested is excreted intact in the urine. There is no significant accumulation in milk or tissues.

Metsulfuron is stable to hydrolysis at neutral to alkaline pH. In acid conditions it hydrolyses in water with a half life of 21 days at ph 5 and 250C and > 30 days at ph 5 and 150C.


Water solubility at 25 C. - 1100 mg/L at pH 5; 2790 mg/L at pH 5; 9500 mg/L at pH 7

Octanol:Water ratio at 25 C. - 1.0 at pH 5; 0.014 at pH 7

Vapour Pressure at 25 C. - Very low. 2.5 x 10-12

Dissociation constant - 3.3 pKa

Melting point - 158 C.

Molecular weight - 381.37. SG 0.53 g/mL.

Half life in water - 33 days at pH5 and 25 C. 2.1 days at pH5 and 45 C. 33 days at pH7 and 45 C.


2.Concentration of Active Constituent : 200g/kg
3.Formulation : Water-dispersible Granules.
4.Poison Schedule : Exempt from scheduling
5.Trade name : Crossbow
6.Product Colour : Tan to brown granule.
7.Product Flammability : Non flammable
8.Dangerous Goods Class : exempt
9.Shelf Life : Unlimited if kept dry.
(When stored under ideal conditions- refer Page 4)
12.Effect of Soil Texture on Herbicide : Residual weed control may be reduced on light soils under heavy rainfall.
13.Effect of Soil pH on Herbicide : Using metsulfuron on highly alkaline soils (pH 8.5+) may result in reduced tolerance of following crops. Most rapid breakdown occurs in warm, moist acid soils.
14.Effect of Soil Organic Matter on Herbicide : Residual weed control may be reduced on high organic matter soils.
15.Mode of Action : Post-emergent - Foliar translocated. Some root absorption may occur after rainfall.
20.Effect on plants : Yellowing, stunting.
21.Effect on Legume Species : Knockdown and residual effects will occur on legume species.
22.Soil Moisture at Application :
DRY - Reduced efficacy will occur due to weed stress.

MOIST - Ideal.

23.Frost Effects : Immediately prior to, during and after application possible decrease in efficacy as weeds are stressed.
24.Frost Free Days Required After Application : Not just a function of frost - will depend on daily temperatures which will influence the rate of growth.
25.Effect of Application Water Quality on Herbicide :
Saline Water - Little effect.

Soil Colloids - Little effect.
26.Recommended Water Volume : 1000 L/ha for high volume hand spraying.
27.Nozzle Type : No. 6 to 8 cone nozzle at 700-1500 kPa for high volume hand spraying. Flat fan at 200-300 kPa for boom spraying.
28.Recommended Nozzle Pressure : See above.
29.Recommended Filter Size :
30.Recommended Wetter: Non-ionic or organosilicone surfactant or spray oil.
Eg. 0.1% non-ionic active constituent at 100 mL/100 L.
31.Other Additives : Not recommended.
32.Rain Fastness : 2 hours.
33.Time Interval Before Effect is Noticed : 7 - 30 days.
36.Withholding Period : 0 days. But if area is to be grazed suggest 1-2 days to allow product to be translocated throughout target plant.
37.Plant-Back Period : Wheat - 10 days, Linseed - 9 months, Barley - 6 weeks, Lucerne - 9 months, Peas - 9 months, Medics - 9 months, Lupins - 9 months, Clovers - 9 months, Safflower - 9 months, Japanese Millet - 14 months, Oats - 9 months, Maize - 14 months, Faba Beans - 9 months, Sorghum - 14 months, Chickpeas - 9 months, Sunflower - 14 months, Rapeseed - 9 months, Soybeans - 14 months
38.Spray Tank Clean-Up : Drain tank and flush with clean water for a minimum of 10 minutes. Fill tank with clean water and add 300 mL household chlorine (4%) bleach/100 L water, flush hoses and stand 15 minutes with agitation engaged, repeat. Rinse tank, hoses and boom thoroughly with clean water to remove traces of bleach. Remove and clean nozzles and screens separately. Remove all traces of liquid fertilisers or adjuvants containing ammonia, such as ammonium sulphate or ammonium nitrate, before adding chlorine bleach, because bleach and ammonia will react to release a toxic gas.
Picloram component:

4 CHEMICAL GROUP: I. Herbicide


Grazon, Garlon, Tordon, Access


A translocated, residual herbicide for the control of woody weeds.


Best results when plants are actively growing.

Apply to dry plants.

Maximum tank storage time - 1 week.


Spray oils may improve weed control.



See HerbiGuide.


Unlikely to occur under normal use patterns. However, there may be populations of weeds that have or will develop resistance.


Cotton overalls, washable hat, elbow length neoprene gloves and face shield or goggles.


Wear protective clothing until the spray has dried.


Uptake and translocation:

Absorbed through roots, leaves, bark or from the cut stump.

Physiological effects:

Hormone herbicide with wide ranging effects. Disrupts plant cell growth.

Residual Life and Breakdown:


Broad leaf species are generally more sensitive than grass species.


Leaves usually turn red within a few weeks of application then fall off.




Harmful if swallowed. Will irritate eyes, nose, throat and skin.


Poison Schedule - S6

Mammalian toxicity - Low.

Acute oral LD50 - >2000 mg/kg (rats), [For comparison table salt is 3000 mg/kg].

Skin - Acute dermal LD50 - > 2000 mg/kg (rabbit). Repeated contact may cause allergic disorders.

Eye - May cause temporary, moderate eye irritation.

Vapour inhalation - LC50 > 8 mg/L - Low. Excessive exposure to solvent inhalation may cause eye and respiratory irritation, headache, dizziness and narcotic effects.

Chronic oral toxicity NOEL (picloram) - 0.5-7 mg/kg/day for two years.

Not mutagenic, carcinogenic or teratogenic (i.e. does not cause cancer or reproductive problems).

Does not accumulate in the body.

Effects have been reported in the livers of test animals.

Other Species -

Birds - low toxicity. LD50 mallard ducks and bobwhite quail > 2000 mg/kg. Dietary LC50 mallard ducks and bobwhite quail > 10000 mg/kg.

Fish - Picloram has moderate toxicity. LC50 trout and catfish 5-20 mg/L

Invertebrates - slight toxicity. LC50 Daphnia magna ~ 70 mg/L. 21 day NOEL for survival and reproduction ~12 mg/L.

Bees - picloram has low toxicity. LD50 > 10 ug/bee.

Livestock - picloram do not accumulate in animal systems.

Bioaccumulation - fish do not accumulate picloram.


Will irritate eyes.

Repeated exposure may cause allergic reactions.


Contact a doctor or Poisons Information Centre on 13 11 26.

If Swallowed - Contact a doctor immediately. If more than 15 minutes from medical help then induce vomiting preferably using Ipecac Syrup APF. Never give fluids or induce vomiting if the patient is unconscious or convulsing.

If on Skin - Wash skin thoroughly with soap and water.

If in Eyes - Flush with water for 15 minutes. See a doctor.

If Inhaled - Remove patient from contaminated area to fresh air.

Advice to Doctor

Treat symptomatically with supportive care.


Picloram is rapidly converted to the parent acids in soil, water, plants and animals.

Picloram is residual in soil with a half life of 1-3 months. It is broken down mainly by microbial action.

Picloram has a half life in water of 1 to 40 days in water depending mainly on sunlight intensity. It is broken down in water by ultra violet radiation and is stable to hydrolysis at neutral to alkaline pH. It is broken down in soil by photo degradation and microbial action and has a half life in soil ranging from weeks to months. It normally remains in the top 30 cm of soil but may be found deeper on soils with poor adsorption properties.

It is stable in intact plants.

It can move in run-off water after heavy rainfall events as it dissolves in water rather than attaching to soil particles.

Ground water contamination is possible.

Replanting intervals - 12 months for most species to 4 years for some species. Accumulation in milk and tissues has not been found.


Water solubility at 25 C. - miscible.

Oil solubility - Not normally mixed with oils.

Octanol:Water ratio at 25 C. - at pH 5;
Vapour Pressurepicloram acid 6.15 x 10-7 mm Hg at 350C
Dissociation constant - pKa

Melting point - C.

Boiling Point - 100 C

Molecular weight - SG 1.15 g/mL @20 C.

Half life in water - 1-40 days.

Not corrosive

Non flammable.


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.


6. Product colour : Amber liquid

7. Product Flammability : Not flammable. Flashpoint 82C (PMCC)

8. Dangerous Goods Class :

9. Shelf Life :

10. Mixtures Compatibility :

12. Effect of Soil Texture on Herbicide : May leach on very sandy soils under high rainfall.

13. Effect of Soil pH on Herbicide : Minimal.

14. Effect of Soil Organic Matter on Herbicide : Breaks down more quickly in high organic matter soils.

15. Mode of Action : Disrupts cell growth.

16. Application Timing : Wide.

19. Weeds Controlled : woody weeds

20. Effect on Crop : Not usually used in crop situations.

21. Effect on Legume Species : Kills them.

22. Soil Moisture at Application :

DRY - Don't spray drought stressed plants.

MOIST - Ideal

WATERLOGGED - Don't sprayed waterlogging stressed plants.

23. Frost Effects :

24. Frost Free Days Required After Application :

26. Recommended Water Volume : 3000-4000 L/ha for hand spraying.

27. Nozzle Type : No. 6 to 8 cone nozzle at 700-1500 kPa for hand spraying. Flat fan at 200-300 kPa for boom spraying.

28. Recommended Nozzle Pressure : See above.

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

30. Recommended Wetter : None, nonionic or organosilicone surfactant.

31. Other Additives : Organosilicone surfactants e.g. Pulse® improves control on some weeds.

32. Rain Fastness : 1 hours.

33. Time Interval Before Effect is Noticed : 1 week to 1 month.

34. Weed Symptoms : Leaves turn red then fall off.

36. Withholding Period : Not required when used as directed on label. Don't apply to blackberries with mature or near mature fruit.

37. Plant-Back Period : Don't plant crops for 9-12 months after spraying.

Spray Tank Clean-Up : Drain tank and flush with water. Half fill with water and add 5g of alkali detergent (eg Surf®, Omo®, Drive®) per litre of water and circulate through system for at least 1 minutes then rinse through nozzles. Fill the tank with clean water and rinse and flush through nozzles to remove detergent. Remove the nozzles and screens and clean separately.

Numbered data adapted from "Crop Herbicide Information " by A.J. Chambers.