Iodosulfuron plus mefenpyr

1 Trade nameManufacturerForm



3 ACTIVE INGREDIENTS: Iodosulfuron 100g/L + mefenpyr

Was Hussar with 50 g/kg iodosulfuron
4 CHEMICAL GROUP: B Sulfonylurea


BensulfuronBensulfuron 600g/kg
BroadstrikeFlumetsulam 800g/kg
ChlorsulfuronChlorsulfuron 750g/kg
CrusaderPyroxsulam 215g/kg + cloquintocet-mexyl 451.5g/kg
CrusaderPyroxsulam 30g/L + cloquintocet-mexyl 90g/L
EclipseMetosulam 100g/L
ExpressTribenuron methyl 750g/kg
FlameImazapic 240g/L (to 900g/kg)
Harmony MMetsulfuron 68g/kg + thifensulfuron-methyl 682g/kg
Imazapic plus ImazapyrImazapic 525 + Imazapyr 175g/L
ImazapyrImazapyr 250g/L or 750g/kg
IntervixImazamox 33g/L + imazapyr 15g/L
Iodosulfuron 100Iodosulfuron 100g/kg
Iodosulfuron plus mefenpyrIodosulfuron 100g/L + mefenpyr
LightningImazapyr 175g/L + imazethapyr 525g/L
Logran 750Triasulfuron 750g/kg
Mesosulfuron 30Mesosulfuron 30g/L
Metsulfuron-methylMetsulfuron 600g/kg
Raptor WG 700Imazamox 700 g/kg
SempraHalosulfuron 750g/kg
SpinnakerImazethapyr 700g/kg (or 240g/L)
SulfometuronSulfometuron 750g/kg
SulfosulfuronSulfosulfuron 750g/kg
TitusRimsulfuron 250g/kg
TrifloxysulfuronTrifloxysulfuron 750g/kg


Iodosulfuron is used mainly as a post emergence herbicide for control of a range of grass and broad leaf weeds in wheat and turf.
It is a selective and translocated herbicide that is absorbed through the leaves and roots. It is of low toxicity to mammals, birds and fish. Iodosulfuron acts on the AHAS (acetohydroxyacid synthase) enzyme in plants which is not present in animals and this is the main reason for its low toxicity. It presents little hazard to the environment because it is used at low rates and degrades relatively quickly in most field situations. Plants resistant to iodosulfuron have developed and are expected after repeated use.
Many Annual Ryegrass populations in cropping areas are resistant to Iodosulfuron and other group B herbicides.


Add a non ionic wetting agent or spraying oil such as Hasten®. Some spraying oils increase weed control but may cause crop damage.
Iodosulfuron is usually mixed with 30-100 L water per hectare and broadcast through hydraulic nozzles. It can be applied in ultra low volumes of carrier.
Acidifiers may increase iodosulfuron absorption, especially on waxy plants.
Weeds are most sensitive and crops most tolerant of iodosulfuron when they are young and actively growing. Under cold, wet or stressful conditions the weeds become more tolerant and the crop less tolerant of the herbicide.
For each 10 degree drop in temperature the crops ability to break down iodosulfuron drops by a factor of 2 to 5, thus under cold conditions crop damage is more likely.
Rain within 8 hours of application may reduce the effectiveness of post-emergence applications. Most of the herbicide is washed off leaves by the first 4 mm of rain.
Temperature and relative humidity have little effect on the effectiveness of iodosulfuron apart from their indirect effect on plant growth rates.
Crops physically damaged by wind, sandblasting, hail or insect attack may be damaged by the application of iodosulfuron.
Some crop yellowing and growth retardation may occur within a month of spraying especially if the crop is stressed.
Applications on dry sandy soils followed by leaching rains may result in crop damage.
Crop damage may occur on highly alkaline soils with a pH>8.5.
Avoid mowing turf for 3 days before or after application. Don't feed clippings to stock for slaughter as MRL's have not been set.


Rainfast in 8 hours.
Frost effects: Frosts immediately prior to, during and after application may result in reduced efficacy because the weeds may be stressed and the risk of crop damage increases because the crop is detoxifying the herbicide more slowly.
Inversions: Avoid application during low level inversions as excessive drift may occur.
Temperature: In cold conditions, effects on the crop will be greater.
Delta T and relative humidity: Avoid application when Delta T is greater than


Wetting agents: Non ionic wetting agent is recommended on the label. This may increase the absorption of the herbicide.
Spray oils: Hasten Spray oil is recommended on the label. Other spray oils can be used to increase the absorption of the herbicide.


Hard water: May reduce its effectiveness.
Salty water: Salt up to levels accepted for stock drinking water are usually has little effect on performance. Very salty water may reduce its effectiveness.
Colloids: Little effect.
pH: Do not use with acid water. If pH of water is less than 5.5 then use a buffer to raise the pH to 7. Do not tank mix with products that acidify the water.
Tank life: About 2% of iodosulfuron activity could be lost each day it is kept in the spray tank during warm weather if the water is acidic (pH5) or acidifiers have been added. Avoid keeping the spray mix in the tank overnight because it may settle or breakdown.


Trace elements: Iodosulfuron forms stable metal and ammonium salts so it is incompatible with most trace elements including zinc and ammonium sulphate.
Do not tank mix with products that acidify the water.
Iodosulfuron is antagonistic with diclofop and other grass herbicides.
Iodosulfuron may be synergistic with hormone herbicides and metsulfuron.
Organophosphate insecticide application within 7 days before application or 3 days after application may cause increased yellowing of turf.
Don't tank mix organophosphate insecticides with iodosulfuron.
See HerbiGuide Compatibilities button.


Continuous agitation is required to maintain a suspension.

Boom sprays:

Carrier volume: 50-100 L/ha boom recommended on label. Rates down to 20 L/ha are used in the field providing good coverage of weeds is maintained.
Nozzles: Flat fan.
Pressure: 150-400 kPa.
Droplet size: 200-300 micron.
Filter size: 100 mesh. Finer filters may result in increased blockages.

Aerial application:

Carrier volume:


Clean up:
Clean soon after spraying to reduce the risk of forming dried deposits that may be difficult to remove.
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 filters and clean separately and allow to soak in a mixture of 500 mL chlorine bleach (4%) 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 filters and nozzles in water and replace.


Plant populations tolerant to iodosulfuron are expected to occur naturally after repeated use. Plants that are resistant to group B (Sulfonylurea) herbicides will normally be resistant to iodosulfuron.
Tolerant crops can be developed.
Herbicide resistance is due to plants with a less sensitive enzyme or with an increased ability to break the herbicide down.
Black Nightshade are naturally tolerant.


Some crops should not be planted for many months after iodosulfuron application. This is because they are sensitive to extremely low levels of iodosulfuron and not because of high levels of persistence of the herbicide in the soil.
Barley1 day
Beans21 months
Bluegrass9 months?
Canola9 months
Cereal Rye1 day?
Corn9 months?
Cotton9 months?
Flax9 months?
Guar9 months?
Lentils21 months
Lucerne9 months?
Lupins9 months
Medic21 months
Millet; Pearl9 months?
Millet; Setaria9 months?
Mung Beans9 months?
Mustard9 months?
Oats9 months?
Onions21 months?
Ornamentals12 months
Peas21 months
Potatoes9 months?
Ryegrass9 months?
Safflower9 months?
Sorghum9 months?
Soybeans9 months?
Sugar Beet21 months?
Sunflowers9 months?
Triticale1 day?
Wheat1 day


AllHarvestNot required
AllGrazing28 days


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:

Soil texture: Crop damage may occur on light sandy soils when leaching rainfall follows application.
Soil pH: Don't use on highly alkaline soil with pH>8.5. Damage to turf may occur on alkaline soils with a pH greater than 8.5.
Soil organic matter: Do not apply to soils very low in organic matter as crop injury may occur.
Soil moisture at application: Requires good soil moisture for best results. In dry soils, root uptake is reduced thus efficacy is reduced.
In waterlogged soils, poorer weed control may occur due to as plants being under stress. Crop damage may also be greater due to reduce rates of breakdown within the plant.
In soils where there are marginal levels of zinc and copper, the use of iodosulfuron on wheat may induce a deficiency in these trace elements causing a subsequent yield loss. See crop tolerance section below for remedial action.

20-35 Iodosulfuron Mode, Toxicity, Fate, Properties & Regulations