'Specific off-label approval' trials of herbicides for use in UK soya

Abstract

Trials were carried out at Carbrooke, Norfolk (sandy loam), Preston St Mary, Suffolk (clay loam), Stixwould, Lincolnshire (sandy loam) and Bourne, Lincolnshire (silt clay loam) on commercial crops of soya during 2002 and 2003. The primary objective was to provide soya seed samples to generate residue data in support of an application for specific off-label approval (SOLA). Five herbicide treatments were evaluated; these were: untreated control (no herbicide); Aramo (Tepraloxydim) @ 1.5 litres product/ha @ GS V2; Alpha Linuron @ 0.8 litres product/ha at a light soil site (Carbrooke) or Alpha Linuron @ 1.4 litres product/ha at a heavy soil site (Preston) applied post-drilling, pre-emergence; Flex (Formesafen) @ 0.45 litres product/ha plus Silwet (@ 0.1% of total spray volume) @ GS V1 followed by a repeat dose 1 month after first application and Flex (Formesafen) @ 0.9 litres product/ha @ GS V2.

The field experiments were done to GLP in both years and provided soya seed for residue testing in support of a SOLA application for the most commercially important soya herbicides. Residues of Flex and Alpha Linuron were not detected in the harvested seed and a SOLA was approved for Flex. Residue analyses were not carried out for Aramo due to technical difficulties with the analysis method. A SOLA for Alpha linuron was not submitted, as the herbicide is not being used commercially. Additional information on weed control was gained from the experiment and a range of weeds were controlled by the herbicides, each product having specific strengths and weaknesses. Some herbicides caused crop scorch but this did not have an adverse effect on yield. Yield was increased by 0.71 t/ha (49%) where weeds were controlled.