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Extra weapon in grassweed fight

A new herbicide, INT804, could challenge existing pre- and early post-emergence grass and broadleaved weed killers in winter wheat if approved, says manufacturer Interfarm.

In development trials flumioxazin gave, “incredibly good control” of all the relevant autumn weeds in winter wheat, the firm’s David Stormonth says. Optimum timing is early post-emergence up to GS14 of the crop, but it also has useful activity pre-emergence.

Its real strength appears to be in controlling broadleaved weeds, including those that are regarded as more difficult to control with current products, such as fumitory and groundsel, he says. Other weeds it has good activity on include charlock, cleavers, pansy, speedwells and mayweed. “Its broadleaved weed control is outstanding.”

Grassweed activity is not quite so strong – it gave 90% control of annual meadowgrass in trials, while blackgrass is moderately susceptible. Even so, it has the potential to be a very good start for grassweed control programmes, Dr Stormonth suggests. “It will compete, if approved, with products such as Crystal and Liberator.”

In trials 30g ai/ha of flumioxazin applied post-emergence gave a comparable result to pendimethalin + flufenacet (as in Crystal), while similar results were seen from sequences of flumioxazin or Crystal followed by Atlantis (mesosulfuron-methyl + iodosulfuron-methyl-sodium), he says.

“I envisage it being used alone early post-emergence in sequence with another product for blackgrass control. But there will be some tank-mix options for controlling annual meadowgrass and ryegrass.”

The active is from a new group, the phenylphthalimides, and has a different mode of action from any current product. That means Interfarm is not expecting any cross-resistance issues with the product, although trials are ongoing to confirm that.

If registration goes according to plan the product should be available next autumn, Dr Stormonth hopes.


 Launched at Crop Protection in Southern Britain conference

 New active ingredient – flumioxazin

 Activity pre- and early post-emergence

 Strong on broadleaved weeds

 Place in grassweed programmes

Extra weapon in grassweed fight

26 November 1999

Extra weapon in grassweed fight

TEPRALOXYDIM, a new herbicide from BASF, offers growers a new tool to tackle blackgrass and couch in broad-leaved crops.

It could be particularly useful for growers battling with resistance. "Target-site resistant blackgrass normally has very high resistance to all fops and dims. But tepraloxydim is much more active," says IACR-Rothamsteds Stephen Moss.

Outdoor container work at the Herts research station showed efficacy was only slightly cut by target-site resistance, with over 83% control on all populations of blackgrass, regardless of resistance mechanism.

But growers are urged to exercise caution when exploiting this benefit. "Growers shouldnt come to rely on it as a complete solution," says Dr Moss.

BASF product manager Andrew Jones agrees. "We are not saying it is an anti-resistant strategy. It is dim chemistry and growers should not rely on one mode of action."

Approval for use in sugar beet, peas, beans and winter oilseed rape is expected for spring 2001. Price will be pitched to compete in the oilseed rape cereal volunteer market.

All main annual grassweeds are controlled, with a 0.8-1 litre/ha rate recommended for most, rising to 1.5 litres/ha for annual meadow grass and 2 litres/ha for couch control.

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