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

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