10 August 2001


DESPITE water company pressure for a ban on its use, isoproturon (IPU) looks set to remain quite widely used on cereals this autumn, albeit with the stewardship guidelines introduced last year.

"There are no anticipated changes in legislation from PSD that will affect IPU use in autumn 2001," says Steve Higginbotham, Aventis product stewardship manager.

Maximum annual dose of active ingredient remains 2500g/ha and there are no buffer zone requirements.

The herbicide still has a strategic role to play in controlling key grass weeds and some broad-leaved weeds, being particularly useful against annual meadow grass and sterile brome, he notes.

"It is one of a limited range of options for grass weed control in winter barley and one of a limited group of active ingredients controlling ryegrasses in wheat and barley.

"It is widely available, has a wide range of tank mix options and its use is familiar to growers and agronomists. It is also very cost-effective, I hesitate to use the word cheap."

Although some growers are bound to switch to newer contact products, especially for controlling difficult blackgrass, Mr Higginbotham anticipates reasonably high IPU usage this autumn for three reasons.

After last autumns spraying difficulties, caused by deteriorating field conditions, a shift back to earlier applications of residuals is a distinct possibility. "Growers may not want to risk later applied contact products."

Agronomists in blackgrass areas are also considering the role of IPU as a pre-treatment for Lexus (flupyrsulfuron) to increase residual control and help manage wild oats, he says.

Low profits from last years harvest may also see growers turning to lower-priced proven products, he adds.

"But the issue of IPU and a number of other products that find their way to surface water is real and does cause concern to water companies. It is, therefore, of utmost importance, to protect local streams and ditches and protect the continued availability of IPU, that farmers and spray operators familiarise themselves with the stewardship guidelines and understand that the smallest drip or splash does contaminate surface water."


THE IPU Stewardship Group recognises the need to protect surface water and is maintaining last years voluntary stewardship guidelines that limit applications beyond Nov 1 to 1500g/ha of active ingredient, including spring use, which will lead to less contamination through field drains.

The handling guidelines and practical tips for sprayer operators developed from the Cherwell Study to reduce point source contamination of water supplies still hold good (see panel).

"The Stewardship Group will continue to promote the guidelines and good practice to farmers, sprayer operators and industry influencers," says Mr Higgin-botham.

Aventis IPU packs include stewardship guidelines for operators, he notes. "It is important that they are read.

"The Stewardship Group will continue to promote the guidelines and good practice to farmers, sprayer operators and industry influencers." &#42

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