It is a relatively non selective and translocated herbicide that is absorbed through the leaves and roots. Its main uses are for the control of a large variety of grass and broad-leaved weeds in industrial situations. It is of low toxicity to mammals, birds and fish. Sulfometuron acts on the ALS enzyme in plants which is not present in animals and this is the main reason for its low toxicity. Its main environmental hazard is transport in water over recently treated areas. Plants resistant to sulfometuron have developed and are expected after repeated use.
7 APPLICATION METHODS AND TIPS:
Sulfometuron is usually mixed with 30-200 L water per hectare and broadcast through hydraulic nozzles. It can be applied in ultra low volumes of carrier.
Surfactants and spray oils usually increase weed control especially grasses.
Acidifiers may increase sulfometuron absorption, especially on waxy plants.
Young, actively growing weeds are most sensitive Under cold, wet or stressful conditions the weeds become more tolerant of the herbicide.
Rain within a few hours of application may reduce the effectiveness of post-emergence applications.
Rainfast in 4 hours for post emergent applications.
Frost effects: Frost reduces post emergence activity.
Wind: High winds may cause excessive droplet drift and off target damage. Allow a 100 m buffer with winds of 20 kph and medium droplet sizes.
Inversions: Don't apply in inversion conditions as drift may cause extensive damage.
Temperature: Post emergent activity is generally lower under low temperature conditions.
Delta T and relative humidity: Avoid application when Delta T is greater than
Adjuvants are not necessary for pre emergence applications.
Wetting agents: Non ionic surfactants increase the absorption.
Spray oils: Spraying oils increase the absorption.
10 WATER QUALITY:
Hard water: Avoid hard water.
Salty water: Avoid salty water.
Colloids: No significant effect. Clearing agents are often more antagonistic than the colloids.
pH: Tolerates a wide range of water pH.
Tank life: Several weeks.
Sulfometuron forms stable metal and ammonium salts so it is incompatible with most trace elements and ammonium sulphate.
Hard or salty water may reduce its effectiveness.
Apply by boom spray or aircraft. Water volumes greater than 30 L/ha are usually adequate. Use medium to coarse sprays if drift needs to be minimised.
13 SPRAYER DECONTAMINATION:
Remove nozzles and filters and clean separately. Triple 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. This procedure is sufficient for spraying in other cereals or non selective applications.
Remove the nozzles and screens and clean separately and allow to soak in a mixture of 500 mL chlorine bleach per 10 L water for at least 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. Drain tank and flush with clean water for a minimum of 10 minutes to 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.
Fill tank with clean water and add 300 mL household chlorine (4%) bleach per 100 L water, flush through hoses and boom then stand for 15 minutes with agitation engaged, repeat. Rinse tank, hoses and boom thoroughly with clean water to remove traces of bleach.
Rinse screens and nozzles and replace.
14 HERBICIDE RESISTANCE:
Plant populations tolerant to sulfometuron are expected to occur naturally after repeated use.
Sulfometuron may not be effective on some group B resistant plants.
15 REPLANTING INTERVALS:
Most broadacre crops
12 months or more depending on rate.
1 day at low rates.
16 WITHHOLDING PERIODS:
17 RE-ENTRY PERIOD:
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.
Longer residual on high pH alkaline soils.
More likely to leach and cause crop damage on soils with low clay and organic mater contents.
20 MODE OF ACTION:
Most of the sulfometuron applied to leaves is absorbed. Most is translocated in the phloem. Absorption by roots from the soil solution is not as efficient but this is compensated for by better movement up to the leaves. Within the plant, sulfometuron stops cell division very quickly by its action on the ALS enzyme. Degradation products are non toxic and herbicidally inactive. Secondary effects on photosynthesis, respiration and ethylene production produce the symptoms of yellowing and reddening of grasses and leaf drop in broad-leaved weeds.
Species tolerant to sulfometuron such as the Bermuda grass degrade it more quickly than do sensitive plants. Herbicide resistance appears to be due to plants with a less sensitive ALS enzyme.
It does not normally affect seed germination.
The tolerance of crops or trees to sulfometuron is reduced in soils with high pH, sandy soils, soils with marginal zinc, manganese or copper levels and if leaching rains occur soon after spraying.
On areas where sulfometuron has induced trace element deficiencies the following may reduce losses;
1 kg zinc sulphate plus
1 kg copper sulphate (or 0.5 kg copper oxychloride) plus
4 kg manganese sulphate (or 6 L Mangasol) plus
250 mL wetting agent in 100 L/ha of water applied in the cool of the day or at night.
5-7 days later spray a mix of 30 kg Urea in 100 L/ha water in the cool of the day. Pre mix urea in water to prevent freezing in the spray tank.
Effect on Clover Species:
Effect on Medic Species:
Effect on Lucerne:
Kills young lucerne and severely damages established lucerne.
Effect on Native Plants:
Eucalypts are reasonably tolerant. Low levels from drift are not expected to cause significant problems. Water flowing from treated areas can cause significant damage.
22 DISEASE AND INSECT EFFECTS:
23 PLANT SYMPTOMS:
Growth stops soon after application. About a week later plants will start to yellow or redden. In broad-leaved weeds this may be an intervenal yellowing. Annual weeds are usually dead within 4 weeks of spraying. Under cold and wet conditions they may remain alive as severely stunted plants with few roots and die from water stress in spring. Sulfometuron has little effect on germination and weeds may emerge and grow for a week or two before dying.
Low toxicity to mammals, birds, bees, invertebrates and fish.
Single doses of sulfometuron do not usually evoke any symptoms in animals.
Repeated high doses may lead to red blood cell destruction and other effects.
The main enzyme (ALS) that is attacked in plants does not occur in animals.
May cause eye irritation, tearing or blurred vision.
Overexposure on skin may cause a rash.
26 FIRST AID:
If SWALLOWED: No intervention is necessary. Do NOT give anything by mouth to a semiconscious or unconscious patient.
If in EYES: Irrigate with plenty of water for !5 minutes. If the patient has contact lens, remove these after the first 5 minutes of irrigation.
If on SKIN: Rinse with plenty of water, remove contaminated clothing, wash with soap and water.
If INHALED: Remove patient to fresh air. See a doctor.
Advice to doctor: Treat symptomatically.
Contact the Poisons Information Centre on 131126.
27 ENVIRONMENTAL FATE:
Half life in soil: Sulfometuron has a half life in soil of about 12 months. Its half life is much longer in soils with high pH. At a soil pH of less than 7 it is broken down by hydrolysis and microbial degradation. At a pH of more than 8 there is little hydrolysis and only microbial breakdown. Breakdown is most rapid in warm, moist, acid and light textured soils with a high organic level.
Half life in water: 18 days at pH5 and 25 C. 1.8 days at pH5 and 35 C. 20 days at Little is naturally degraded due to exposure to sunlight and volatilisation.
On the EPA classification of mobility in the soil it ranges from low mobility to mobile depending on the soil type. Mobility usually increases with increasing soil pH and decreasing organic matter.
Ground water contamination:
Accumulation in milk and tissues: Sulfometuron does not accumulate in the milk or tissues of animals. Most is excreted intact in the urine of monogastric animals or as a conjugate in ruminants.
pH stability: More stable at higher pH.
Photolysis rate: Low.
Hydrolysis half life: Depends on pH. It is shorter at low pH and high temperatures.
Biodegradation rate: Slow.
28 REGISTERED CROPS:
See HerbiGuide Species Solution tab.
29 REGISTERED WEEDS:
See HerbiGuide Species Solution tab.
30 REGULATION AND LEGAL:
UN number: None allocated.
CAS numbers: 74222-97-2
Hazchem code: None allocated.
NOHSC classification: Not hazardous. No risk or safety phrases.
Dangerous goods class: Not a dangerous good. No special transport requirements.
No special transport requirements.
Proper shipping name:
Colour: Off white to buff.
Odour: Odourless to mild odour.
Form: Solid granules, dry flowable.
Water solubility at 25 C. - 8 ppm at pH 5; 70 ppm at pH 7. Disperses in water.
Octanol:Water ratio at 25 C. - 15 at pH 5; 0.31 at pH 7
Soil organic carbon absorption coefficient (Koc):
Vapour Pressure at 25 C. - Very low. 5.5 x 10-16
Dissociation constant - 5.2 pKa.
Melting point - 203 - 205 C for sulfometuron methyl.
Boiling point: C.
Molecular weight - 364.39
Bulk density: 0.62-0.71 g/cm3
pH 8 and 35 C. (Similar acidity to vinegar or acetic acid)
Flammability: Not flammable.
Flammable limit in air: LEL = 0.092 g/L. Not normally an explosion hazard but dust may form an explosive mixture with air.
Shelf Life: 5 years.
(When Stored under Ideal Conditions)
Sweep up spills.
Extinguish with water spray, foam, carbon dioxide or dry agent. Prevent contaminated water reaching desirable vegetation.