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Gator H20


APVMA code: 69635/61296 

Active Constituent(s):

240 g/L carfentrazone-ethyl

solvent: 261 g/L liquid hydrocarbon

Registered For:


 Commercial use

 Domestic use

Overview: For the control of certain aquatic weeds in rice. 

  SDS  (74 KB)

  Label  (216 KB) 

General Instructions

GATOR H2OHerbicide is an early post emergence herbicide for the control of certain broadleaf and sedge weeds in rice. GATOR H2O is a fast acting contact herbicide and controls weeds through a process of

membrane disruption. Application of GATOR H2O should target small actively growing weeds. Subsequent germinations will not be controlled.



DO NOT tank mix GATOR H2O with crop oil concentrates or blended oil/surfactant adjuvants.

DO NOT apply GATOR H2O to the long grain rice varieties Kyeema and Doongara.


Withholding Periods - Rice





In rice when applied to permanent floodwater, GATOR H2O is rapidly absorbed through the foliage of plants. Within a few days following application, the foliage of susceptible weeds show signs of necrosis and later death. Herbicidal symptoms may appear on the crop in the form of leaf yellowing on submerged leaves and bronzing on exposed leaves. Do not apply GATOR H2O to the long grain rice varieties Kyeema and Doongara.



GATOR H2O is compatible with the grass herbicide Magister®. GATOR H2O can be tank mixed with Londax DF* for broadened aquatic weed control Do not tank mix GATOR H2O with oil/surfactant blends, as excessive crop injury may occur.


Resistant Weeds Warning

GATOR H2O Herbicide is a member of the Aryl triazolinone group of herbicides. Its mode of action is through a process of membrane disruption, which is initiated by the inhibition of the enzyme protoporphyrinogen oxidase. This inhibition interferes with the chlorophyll biosynthetic pathway. For weed resistance management GATOR H2O is a Group G herbicide. Some naturally occurring weed biotypes resistant to GATOR H2O and other herbicides that inhibit the enzyme protoporphyrinogen oxidase may exist through normal genetic variability in any weed population. The resistant individuals can eventually dominate the population if the herbicides are used repeatedly. These resistant weeds will not be controlled by GATOR H2O or other herbicides that inhibit the enzyme protoporphyrinogen oxidase. Since the occurrence of resistant weeds is difficult to detect prior to use, FMC Crop Protection Pty Ltd accepts no liability for any losses that may result from the failure of GATOR H2O or other herbicides that inhibit the enzyme protoporphyrinogen oxidase. In rice when GATOR H2O is used alone a follow-up application of MCPA is recommended to provide a secondary mode of action.



Application should be made to permanent flood water to small weeds up to 4 to 6 leaf in size, species dependant. When using GATOR H2O alone apply at or beyond the 2 leaf rice stage. When using GATOR H2O in tank mix with Londax apply at or beyond the 2.5 leaf rice stage. Earlier application could result in excessive crop injury.



Add half the required volume of water in spray tank and start agitation. Add the measured amount of GATOR H2O next, followed by Londax DF if tank mixing. Add balance of water to tank. Maintain good agitation at all times until spraying is completed.



GATOR H2O can be applied to permanent flood water by drip application (SCWIIRT method – i.e. Soluble Chemical Water Injection In Rice Technique) and boom spray application. Apply as a drip application (SCWIIRT method) by tractor, 4 wheel agricultural motorbike or helicopter (maximum 20 m swath width) in a total spray volume of 7 to 10 L/ha.

Apply by boom spray application by ground rig or by aircraft in a minimum total spray volume of 20 L/ha. Spray equipment should be properly calibrated to ensure correct application. Application using equipment set to produce coarse droplets will increase direct application onto the water surface, will minimise contact with emerged crop and minimise spray drift. Avoid spraying in still conditions, conditions conducive to inversion and in winds likely to cause drift. Turn off spray boom while passing over irrigation channels, creeks and dams.


Water Management

It is essential to lock up bays 1 day prior to application and hold water for at least 5 days after application. To optimise weed control and minimise crop injury ensure there is sufficient water to cover the crop at application- ideally 5 to 8 cm on the high side of the bay, based on 6 to 10 cm fall across the rice bay.

Normal water levels should be maintained following the 5 day lock up period Do not drain rice water into regional drains, within the withholding period after GATOR H2O application as defined by the local irrigation authority and/or the NSW Environmental Protection Authority.



Do not allow entry into treated areas for 12 hours. When prior entry is necessary, wear impervious footwear and chemical resistant gloves. Clothing must be laundered after each day’s use.


Crop Rotation Recommendations

GATOR H2O Herbicide does not provide residual activity, therefore no crop rotational restrictions apply. However, check the label of any product mixed with Gator H2O Herbicide, to determine any plant back periods or restrictions on use.


Protection of Crops, Native and other Non-Target Plants

Do not apply under weather conditions, or from spray equipment, which may cause spray drift onto nearby susceptible plants, adjacent crops, or pastures, or onto wetlands, waterbodies or watercourses.


Protection of Wildlife, Fish, Crustaceans and Environment

Highly toxic to algae and aquatic plants. DO NOT contaminate streams, rivers or waterways with GATOR H2O or used container.



Storage and Disposal

Store in the closed, original container in a cool, well-ventilated area. Do not store for prolonged periods in direct sunlight.


Spillage - In case of spillage, confine spilled product with material such as sand or clay. Dispose of waste as indicated below or according to the Australian Standard 2507 - Storage and Handling of Pesticides.

DO NOT allow spilled product to enter sewers, drains, creeks or any other waterways. Keep out animals and unprotected persons. Vacuum, shovel or pump waste into an approved drum. To decontaminate spill area, tools and equipment, wash with a suitable solution (ie organic solvent, detergent, bleach or caustic) and add the solution to the drums of wastes already collected. Label for contents. Dispose of drummed wastes, including decontamination solution, in accordance with the requirements of Local or State Waste Management Authorities.


Triple or preferably pressure rinse containers before disposal. Add rinsings to spray tank. Do not dispose of undiluted chemicals on-site. If recycling, replace cap and return clean containers to recycler or designated collection point. If not recycling, break, crush or puncture and bury empty containers in a local authority landfill. If no landfill is available, bury the containers below 500 mm in a disposal pit specifically marked and set up for this purpose clear of waterways, desirable vegetation and tree roots, in compliance with relevant Local, State or Territory government regulations. Empty containers and product should not be burnt.


Safety Directions

May irritate the nose and throat. May irritate the eyes and skin. Avoid contact with eyes and skin. Avoid inhaling vapour. When opening the container, mixing, loading and preparing spray and using the product wear cotton overalls buttoned to the neck and wrist (or equivalent clothing) and elbow-length PVC gloves.

Wash hands after use. After each day’s use, wash gloves and contaminated clothing.


DISCLAIMER: This is not the GATOR H2O label. To view or print the label for this product, click the "MSDS/Label" tab at the top of this page. Always follow label instructions.


For specialist advice in an EMERGENCY only phone 1800 033 111, TOLL-FREE, ALL-HOURS, NATIONWIDE

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pdf Gator H2O Technote

(981 KB)


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