Syngenta is increasing the range of recommendations of its pre-emergence herbicide, Defy (prosulfocarb), to include annual meadowgrass.

The move came as a result of the decision to revoke IPU’s approval earlier this year, product manager Rod Burke said. “Virtually all annual meadowgrass control was built around IPU so there is a massive gap to be filled. We’re picking up distributors are not prepared to hold huge stocks of the product into 2008, so this could be the last year of guaranteed supply.”

Defy’s recommendation would be for 1.5 to 2.0 litres/ha plus 50g diflufenican/ha to broaden out broadleaved weed control, he said. The product could be applied from pre-emergence to up to two leaves of annual meadowgrass.

In three Syngenta trials the higher rate mix had just shaded control over a current standard 1.5 litres/ha IPU + 1.0 litre/ha IPU/DFF mix when applied at peri-emergence, he said.

Defy would “just about” fit into the current common practice of applying herbicide in mix with a BYDV spray, Mr Burke claimed. “But for some broadleaved weeds it may be better to go pre-emergence so the market may shift earlier. Our research suggests there might not be the objection to that we thought there might be.”

The DFF mix with Defy would control most broadleaved weeds, particularly when applied pre-emergence, but it did leave a couple of holes, Mr Burke noted. “A grower needs to be aware if mayweed, poppy and groundsel are going to be serious issues.”

There were alternative tank mix options – for example a mix with the Pico range of products (picolinafen + pendimethalin) was better on poppy and fumitory.

Defy (1.5 litres/ha) + DFF (1.0 litre/ha) would cost around £13.50/ha, he said.