21 March 1997

IPU replacers bring extra

benefits at reduced rates

By Amanda Dunn

TRIALS of isoproturon replacers are not only showing encouraging results on blackgrass but also an enhanced effect on certain difficult to control broad-leaved weeds, it emerged at last weeks Weeds in Focus event at ADAS Drayton.

Work on the Warks site is assessing the scope for replacing a proportion of IPU with an alternative chemical. The detailed weed screen comprises six grasses and seven broad-leaved weeds. Plots were seeded with either susceptible or five star resistant blackgrass at 250 seeds/m2.

"Early indications suggest that IPU replacers are not only having an effect on resistant and susceptible blackgrass, but also a greater effect on broad-leaved weeds than we had expected," says weed specialist Derek Wade of ADAS Rosemaund.

New combination

A new herbicide combination from Rhône-Poulenc has performed well in artificial weed situations.

"The new product contains IPU, diflufenican and new active ingredient flurtamone. At the recommended rate of 3.75l/ha it delivers 1500g IPU, 100g diflufenican and 250g flurtamone. For blackgrass control application timing of the product is recommended at the two to three leaf stage.

"Were achieving the same level of control using 1500g of IPU as we would expect to get using 2500g of IPU," says Nick Duncan, the companys marketing development manager for herbicides.

"Were seeing good control of blackgrass and in addition increased efficacy in some broad-leaved weeds.

"The late season means were still waiting to see the complete effect, but theres little question that this product is a valuable addition to our current range."

"When used alone, were seeing very effective control of susceptible blackgrass, but also signs of increased control of cleavers, cranesbill and fumitory."

When used in a programme, promising results have been achieved against resistant blackgrass. "In a resistant situation wed advocate a programmed approach using products with different modes of action, so in the weed screen we applied 22.5kg/ha Avadex pre-emergence and then followed up post-emergence with 3.75l/ha of the new product.

"The strength of flurtamone is enabling us to control blackgrass with less IPU and offer increased control of some important broad-leaved weeds," concludes Mr Duncan.

New lower rate IPU mixes are giving weed control to match the old full rate approach, says Nick Duncan of Rhône-Poulenc.