1 March 1996

Veg-oil adjuvants show their worth

VEGETABLE oil-based adjuvants could warrant greater attention if a potential ban on mineral oil additives were to be enforced.

Thats the belief of Microcides Steve Silvester. The possibility of a ban on pesticides and adjuvants based on products made from petroleum and paraffin was mooted five years ago, and a ministry spokesman confirms that the Advisory Committee on Pesticides still has the subject under review. However there is said to be no immediate pressure for its introduction.

Whatever the outcome of the review, Mr Silvester suggests that useful results from trials in Suffolk and Scotland last year confirm the value of vegetable oil-based products. Those showed the firms Codacide additive "significantly" boosted weed and disease control from two modern products.

Applied alone in early April against blackgrass in winter wheat, 250ml/ha of Topik (clodinafop-propargyl) gave "virtually complete control" of well-tillered plants by seedhead emergence, he says. But control decreased sharply below the 187.5ml/ha rate.

However, adding Codacide to the recommended rate of 125ml/ha gave "excellent control", says Mr Silvester. There was also a response to the adjuvant below that rate, though in practice this would not benefit the farmer, he concedes.

An SAC trial tested Opus (epoxiconazole) fungicide against Septoria tritici – the only disease present in a crop of Riband. This found that Codacide significantly reduced the infection on leaf three 13 days after spraying and on leaf two 29 days after treatment over all dose rates, he says.

Mr Silvester acknowledges the "one-off" nature of the trials and says more will be done to re-inforce the findings.

Many of Codacides benefits stem from "fine tuning" effects, for example reducing drift and increasing rainfastness, that improve the consistency of results, he says.