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Published: 2 April 2012

Continued restrictions on use of weed-control chemical

Diruon is a chemical used primarily for weed control in cereals, cotton and sugarcane. In November 2011, due to environmental concerns, certain uses of diuron were temporarily prohibited in Australia. This suspension has now been extended until 30 November 2012, pending the release of a final environmental assessment report.

Furrow irrigation of newly planted sugar cane crop near Clare, QLD
Credit: CSIRO, photo by Willem van Aken

Diuron is very toxic to non-target terrestrial plants. In addition to agricultural uses, it is a common weed-control agent in non-agricultural areas such as rights-of-way, and on commercial and industrial sites. It is often used in combination with other herbicides.

In cotton growing areas, in addition to in-crop weed control, it is used to defoliate cotton to facilitate harvest, and to prevent weeds from clogging the open irrigation channels that characterise Australia’s canefields. Between 1996 and 2003, its use in relation to sugar cane increased substantially.

Diuron is also used as an antifoulant in paints to prevent the build-up of marine growth on the hulls of boats.

Following an initial environmental assessment report published in July 2011, a range of suspensions to the use of diuron were made. Since then, the period for submission of responses to the report has closed and the APVMA has received one hundred and thirteen submissions from a range of groups and individuals, including those seeking to register diuron for use in products, diuron users, user groups, state governments and environmental groups.

‘Some of the material [in the submissions] which included data from the Reef Monitoring Program is quite substantial and contains new studies and information in relation to the use and impacts of diuron, so it will require careful consideration,’ says Dr Raj Bhula, APVMA Pesticides Program Manager.

As a result, the APVMA has extended suspensions made in November 2011 following the initial environmental assessment report, including:

  1. total suspension of use in irrigation channels and drains in agriculture (unless all irrigation tailwater and rainfall can be captured and held on-farm)

  2. prohibition of use during a ‘no-spray’ window of time, for a range of tropical crops such as sugarcane, tea, bananas, pineapples, coffee and paw paw.

Diuron remains registered for use in antifouling paints (after variations to label instructions), in pond and aquarium products, and in cotton defoliation products (after variations to label instructions).

The APVMA will finalise its review of diuron after receiving a final environmental assessment report from the Department of Sustainability, Environment, Water, Population and Communities.

Once the final environmental assessment is received from the Department, the APVMA will take at least 12 weeks to develop regulatory outcomes for the future of diuron.

However, in relation to some uses, for which the 2011 environmental assessment report indicated no concerns, the APVMA considers the diuron review finalised and these uses will continue to be approved. They include:

  1. active constituent approvals (approval of suppliers of diuron to product manufacturers)

  2. antifouling paints (continued registration with variations to two label instructions)

  3. pond and aquarium products (continued registration)

  4. cotton defoliation products (registration after variations to label instructions).

More information

Chemical regulator restricts weed killer to protect reef, ECOS, December 2011.

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