Diuron chemical review

Diuron (1,1-dimethyl, 3-(3’,4’-dichlorophenyl) urea) is a broad-spectrum residual herbicide and algaecide used in agriculture for pre-emergent and post-emergent control of broadleaved and grass weeds. It is also used to control weeds and algae in and around water bodies and is a component of marine antifouling paints.

The APVMA began a review of diuron on the basis of environmental and human health concerns (specifically, the potential for diuron to contaminate the marine environment through agricultural run-off and the possible toxicity of some impurities of diuron active constituents).

In July 2011, the APVMA released the Diuron environmental assessment report and the Diuron human health assessment report.

In 2005, the APVMA released the Diuron preliminary review findings report. Following publication of the report, the APVMA received a large body of new information through the then Department of Sustainability, Environment, Water, Population and Communities and assessed that information.

In November 2011, the APVMA suspended the registration of selected diuron products while it considered additional information and submissions provided to the review. One hundred and thirteen submissions were received in response to the release of the 2011 environmental assessment report. A number contained new studies and information about the use and impacts of diuron. The submissions came from registrants, diuron chemical users, user groups, state governments and environmental groups.

In March 2012 the APVMA finalised the review for:

• active constituent approvals (approval of suppliers of diuron to product manufacturers)
• antifouling paints (continued registration with variations to two label instructions)
• pond and aquarium products (continued registration)
• cotton defoliation products (continued registration after variations to label instructions).

At the same time, the APVMA continued the suspension of selected diuron products until 30 November 2012.

In September 2012, the APVMA published the final diuron environmental assessment report received from the then Department of Sustainability, Environment, Water, Population and Communities and proposed to finalise the review based on the findings of this assessment. Diuron product registrants were asked to show cause as to why the review should not be finalised in the manner proposed.

Taking into consideration comments from registrants, the APVMA revised the review recommendations and has now finalised the review of diuron. The outcomes include:

• the cancellation of selected registrations
• varied label approvals to specify amended instructions for use
• affirmed product registrations and consequently cancelled approvals of old labels.

Some uses will no longer be approved, including industrial applications, use in non-agricultural situations, and use on citrus, apples, pears, ornamentals and selected tropical crops (tea, coffee, pawpaw). Other uses have been significantly restricted.

Most products have had their registration affirmed, but with significant restrictions and variations to label instructions. The restrictions are very specific for individual crops, and in the case of sugarcane and pineapple additional seasonal ‘no-spray windows’ apply.

To ensure an orderly phasing in of the new arrangements, the APVMA has issued a PER13874 for 12 months to cover existing stock in the supply chain. This stock can continue to be used according to the arrangements in place under the previous suspension arrangements, including a wet-season no-spray window.

Instructions for the use of cancelled products and registered products bearing a cancelled or varied label: PER13874.

Diuron is a herbicide and algaecide used in a variety of cropping and non-cropping situations

Prior to some diuron uses being suspended in late 2011 and the finalisation of the review in November 2012, diuron was used to:

• control weeds in agriculture—sugarcane, cotton, broadacre crops (oats, wheat, and barley) and some horticultural crops, including apples, pears, citrus, pineapples and bananas
• control weeds in irrigation channels, drainage ditches, around buildings, railway lines, sheds and driveways
• protect boats from marine algal growth (as a component of antifouling paints)
• prevent algal growth in home aquariums and ponds.

There are more than 100 products containing diuron registered for use in Australia.

The APVMA commenced a review of diuron on the basis of environmental and human health concerns, specifically the potential for diuron to contaminate the marine environment through agricultural runoff, and the possible toxicity of some impurities of diuron active constituents.

Using diuron at the originally approved rates of application presented a risk to aquatic ecosystems in most situations. The main risk is that in certain situations of use the concentration of diuron in water runoff following heavy or persistent rainfall may be high enough to cause significant harm to the environment, specifically aquatic plants.

The 2011 human health assessment report raised no concerns in relation to the continued approval of diuron active constituents and diuron product registrations.

The APVMA has concluded that registration of certain products cannot continue and these have had their registrations cancelled. The registration of other diuron products can continue with variations to labels to remove or amend those uses where risk from runoff cannot be managed.

The uses that continue to be approved are asparagus, bananas (low rates), bore drains, cotton, irrigation channels and drainage ditches, lupins, pineapples (low rates), pulses, sugarcane (limits on rates), faba beans, summer fallows, wheat, barley, oats, triticale and cereal rye, subject to additional restraints.

Those where use cannot continue are apples and pears, bananas (high rates), citrus, coffee, driveways, paths, lanes, drains, ditches, fence lines, car parks, tennis courts, duboisia, factory sites, commercial and industrial areas, lucerne, non-crop areas, ornamentals (daffodils, gladioli, tulips, lilium, iris), pawpaws, peas, perennial grass and seed crops, phalaris and cocksfoot, phalaris cultivars sirolan and sirosa, pineapple (high rates), rights-of-way, sugarcane (selected applications and rates), tea and vineyards.

In March 2012, the APVMA completed the review as it applied to active constituent approvals (approval of suppliers of diuron to product manufacturers), antifouling paints (continued registration with variations to two label instructions), pond and aquarium products (continued registration) and cotton defoliation products (continued registration after variations to label instructions). The APVMA also continued the suspension of other diuron products until 30 November 2012. The APVMA finalised the review of diuron and published the Diuron Final Review Report in November 2012.

The actions taken include cancellation of registration for three products, with the remainder having their registration affirmed, but with significant restrictions on how these products can be used.

Some uses, including industrial applications and use in non-agricultural situations, citrus, apples and pears, ornamentals and selected tropical crops (tea, coffee, pawpaw) will no longer be approved. Other uses have been significantly restricted. The restricted uses are complex, with the uses for sugarcane and pineapples having additional region-specific and season-specific restrictions. The APVMA also issued a permit (PER13874) for the supply and use of products whose registration is cancelled or where labels have been cancelled or varied as a consequence of the review. The permit will allow an orderly phaseout of diuron products already in the supply chain or in the hands of users.

A no-spray window is a period of time during which diuron products may not be used at all, even if they are allowed under strict conditions at other times of the year. No-spray windows have been introduced into the label conditions for sugarcane (Queensland and NSW) and pineapple (Queensland) production. The actual no-spray period varies according to specific regional climatic and geographic conditions.

The regions identified in the diuron review reports form the basis of the no-spray windows for sugarcane and pineapple crops in Queensland. These are the same as the Australian Government's Natural Resource Management (NRM)  regions. There are five Queensland regions referenced in the reports: Wet Tropics, Burdekin, Burnett Mary, Mackay Whitsunday and South East Queensland (pineapples only).

References to NSW are references to all regions within the state.

Alternative herbicide products exist. Users can consult the APVMA's database of registered products (PUBCRIS) and/or their state department of agriculture for further information.

The Queensland Government has published information on weed control methods and the NSW DPI has released a weed control guide.

Diuron has been registered and used in many countries. However, it has been reviewed in the United States (draft 2003), Canada (2007), United Kingdom (2007) and Europe (2007 and 2008). Restrictions on the use of diuron in these jurisdictions have been implemented (reductions in frequency and rate of application and restrictions on crop uses) with a view to protecting aquatic environments.

Although antifouling paints containing diuron are no longer permitted for use in the United Kingdom and Europe, the risk assessment approach undertaken in Australia (July 2011 environmental assessment), using a very conservative model, concluded that diuron antifouling use patterns in Australia did not present risks to aquatic organisms.

The APVMA has also concluded that use of diuron for algal control in aquariums and ponds does not pose risks to aquatic organisms, given the low concentrations and application rates allowed in Australia (July 2011 environmental assessment). 

Based on the outcomes of the diuron review significant changes to the way diuron products can be used have been made. The lists below outline approved uses, uses that are not approved and label restraints following the review. Additional regional-specific restraints for pineapples and sugarcane are also provided.

Users will need to review full details of the changes to relevant product labels to ensure full compliance with the outcomes of the review.

Approved uses

• Asparagus—Victoria only
• Bananas—at rates less than 450 g ac/ha
• Bore drains
• Cotton
• Faba beans
• Irrigation channels, drainage ditches
• Lupins
• Pineapples—only when used according to Dupont Krovar DF Herbicide (31253) label instructions and within the permitted window of application. See further details on the Pineapples tab.
• Pulses
• Sugarcane—at rates up to 450 g ac/ha at anytime (when using diuron/hexazinone products only)
• Sugarcane—a rate of application of 1.8 kg ac/ha within the label specified window for application where approved. See further details on the Sugarcane tab.
• Summer fallows
• Wheat, barley, oats, triticale, cereal rye

g ac/ha = grams of active constituent per hectare; m = metres 

Uses not approved

• Apples and pears
• Bananas—at rates greater than 450 g ac/ha
• Citrus
• Coffee
• Driveways, paths, lanes, drains, ditches, fence lines, car parks, tennis courts
• Duboisia
• Factory sites, commercial and industrial areas
• Lucerne
• Non-crop areas
• Ornamentals—daffodils, gladioli, tulips, lilium, iris
• Pawpaws
• Peas
• Perennial grass and seed crops, phalaris and cocksfoot
• Phalaris cultivars sirolan and sirosa
• Pineapple—other than according to instructions on DuPont Krovar DF Herbicide (31253)
• Rights-of-way
• Sugarcane—rates greater than 1.8 kg ac/ha
• Sugarcane—use at 1.8 kg ac/ha outside of approved spray windows
• Tea plantations
• Vineyards

g ac/ha = grams of active constituent per hectare

Label restraints

DO NOT use in water-logged areas

DO NOT apply if greater than 50 mm rainfall is expected within 3 days of application

DO NOT irrigate within 3 days of application

DO NOT apply to fields where the slope exceeds 3%

DO NOT spot spray more than 5% of total farm area

DO NOT apply more than once per calendar year

Cotton

DO NOT use in cotton UNLESS ALL irrigation tailwater and/or up to 25 mm rainfall can be captured and held on farm

Pulse crops

DO NOT use in pulse crops UNLESS application can be made using no-till farming practices

Irrigation channels and drains

DO NOT use in irrigation channels or drains UNLESS ALL irrigation tailwater and rainfall can be captured and held on farm

Desert channels (bore drains)

DO NOT apply between 1 December and 30 March

DO NOT open drains for 72 hours following treatment

SPRAY DRIFT RESTRAINTS

DO NOT apply by air

DO NOT apply when wind speed is less than 3 or more than 20 kilometres per hour as measured at the application site.

DO NOT apply with spray droplets smaller than COARSE spray droplet size category according to nozzle manufacturer specifications that refer to the ASAE S572 Standard or the BCPC Guideline.

Users of this product MUST make an accurate written record of the details of each spray application within 24 hours following application and KEEP this record for a minimum of 2 years. The spray application details that must be recorded are: 1. Date with start and finish times of application; 2. Location address and paddock/s sprayed; 3. Full name of this product; 4. Amount of products used per hectare and number of hectares applied to; 5. Crop/situation and weed/pest; 6. Wind speed and direction during application; 7. Air temperature and relative humidity during application; 8. Nozzle brand, type, spray angle, nozzle capacity and spray system pressure measured during application; 9. Name and address of person applying this product. (Additional record details many be required by the State or Territory where this product is used).

MANDATORY NO-SPRAY ZONES

DO NOT apply when there is non-target vegetation downwind from the application area and within the mandatory no-spray zones shown in table below.

DO NOT apply when there are aquatic and wetland areas including aquacultural ponds, surface streams and rivers downwind from the application area and within the mandatory no-spray zones shown in table below.

g ac/ha = grams of active constituent per hectare; m = metres

Sugarcane

In addition to all of the general label restraints, there are additional region-specific and season-specific restraints on the use of diuron products for sugarcane production in Queensland and NSW.

These restraints include no-spray windows, or time periods, when diuron products may NOT be applied. These time periods vary according to the climatic and geographic situations found on a regional basis. The regions identified for Queensland are defined according to the Australian Government’s Resource Management regions. References to NSW production are for all NSW regions.

Sugarcane—diuron only products

Pre-emergent use (1.8 kg ac/ha)

DO NOT apply in the Wet Tropics

DO NOT apply in Burdekin between 1 December and 29 February

DO NOT apply in Mackay Whitsunday between 1 November and 31 May

DO NOT apply in Burnett Mary between 1 November and 31 May

DO NOT apply in NSW between 1 November and 30 April

Post-emergent use (1.8 kg ac/ha max 60 per cent band spray)

APPLY ONLY as a directed band spray over a maximum of 60 per cent of the crop area

DO NOT apply in the Wet Tropics

DO NOT apply in the Burdekin between 1 January and 29 February

DO NOT apply in Mackay Whitsunday between 1 December and 30 April

DO NOT apply in Burnett Marybetween 1 November and 29 February

DO NOT apply in NSW between 1 November and 30 April

Sugarcane (diuron/hexazinone products)

Pre-emergent use (1.8 kg ac/ha)

DO NOT apply in the Wet Tropics

DO NOT apply in the Burdekin between 1 December and 29 February

DO NOT apply in Mackay Whitsunday between 1 November and 31 May

DO NOT apply in Burnett Mary between 1 November and 31 May

DO NOT apply in NSW between 1 November and 30 April

Post-emergent use (1.8 kg ac/ha, max 60 per cent band spray)

APPLY ONLY as a directed band spray over a maximum of 60% of the crop area

DO NOT apply in the Wet Tropics

DO NOT apply in the between Burdekin 1 January and 29 February

DO NOT apply in Mackay Whitsunday between 1 November and 31 May

DO NOT apply in Burnett Mary between 1 November and 29 February

DO NOT apply in NSW between 1 November and 31 March

kg ac/ha = kilograms of active constituent per hectare

Pineapples

In addition to all of the general label restraints, there are additional region-specific and season-specific restraints on the use of the DuPont Krovar DF Herbicide diuron product for pineapple production in Queensland.

These restraints include no-spray windows or time periods, when this diuron product may NOT be applied. These time periods vary according to the climatic and geographic situations found on a regional basis. The regions identified for Queensland are defined according to the Australian Government’s Natural Resource Management regions.

Pineapples using the product DuPont Krovar DF Herbicide

Pre-emergent use (4.5 kg product/ha)

DO NOT apply in the Wet Tropics

DO NOT apply in the Burdekin between 1 December and 29 February

DO NOT apply in Mackay Whitsunday between 1 December and 31 May

DO NOT apply in Burnett Mary between 1 December and 31 May

DO NOT apply in SE Queensland between 1 September and 31 May

Post-emergent use (4.5 kg product/ha max 60 per cent band spray)

APPLY ONLY as a directed band spray over a maximum of 60 per cent of the crop area

DO NOT apply in the Wet Tropics

DO NOT apply in the Burdekin between 1 December and 29 February

DO NOT apply in Mackay Whitsunday between 1 December and 31 May

DO NOT apply in Burnett Mary between 1 December and 31 May

DO NOT apply in SE Queensland between 1 September and 31 May

Post-emergent use (2.2 kg product/ha max 60 per cent band spray)

APPLY ONLY as a directed band spray over a maximum of 60 per cent of the crop area

DO NOT apply in the Wet Tropics

DO NOT apply in the Burdekin between 1 December and 29 February

DO NOT apply in Mackay Whitsunday between 1 December and 29 February

DO NOT apply in Burnett Mary between 1 December and 31 May

DO NOT apply in SE Queensland between 1 December and 31 May

ha = hectare