25 April 1997

Rape oil aids spraying

RAPESEED oil can be used as a carrier in ultra low volume spraying. But there are practical and registration problems to be overcome, according to an HGCA-funded project report.

IACR-Long Ashton tests on oil- and water-based herbicide applications highlight the potential of the vegetable oil. The work, with commercial formulations of Topik (clodinafop-propargyl) and Betanal E (phenmedipham), compared oil alone sprays at up to 10litres/ha with conventional sprays at 220litres/ha.

Deposits on cereals and fat hen seedlings were seven and three times higher respectively using the oil. Applied alone it left young wheat, sugar beet and tomato plants unharmed.

But herbicide effectiveness varied depending on carrier. Oil seemed to double Topiks value against wild oats, but Betanal was nearly four times more effective on fat-hen in water.

While feasible, the use of oil would need new machinery, says Long Ashtons Eric Hislop. "Metering and atomisation of low flow rates is difficult and pesticide efficacy depends on complex interactions between chemical and plant."n