The SOLA gives growers an additional residual herbicide option to replace the use of Decimate following its withdrawal in 2009. "This gives growers an extra 12 months to use Dacthal on salad onion crops, up until the final use-up date of 23 March 2011," said Certis regulatory affairs officer Sue Young. Growers should note that they only have until 23 March 2010 to purchase the herbicide.

Dacthal is an effective residual herbicide that provides control of a range of broadleaved and grass weeds in a number of crops.

Gaining good weed control within salad onion crops is essential at all times because the crop is a poor competitor against weeds.

Certis technical officer Alan Horgan said: "With the advent of the off-label, salad onion growers are now on an equal footing with bulb onion growers, with both now able to use a reliable herbicide with a high level of crop safety and good efficacy until March 2011."

- Independent herbicide consultant Cathy Knott told last month's Brassica Growers Conference that the Horticultural Development Company has submitted applications to the Chemicals Regulation Directorate for several SOLAs, including BUK 9900 - a residual soil-acting herbicide for the control of annual weeds in transplanted cabbage - and Stomp Aqua, a pendimethalin formulation to be applied in cabbage crops within seven days of transplanting.

Knott added that there is more optimism about alternative treatments for Brassica crops when the new pesticide regulations come into force than other vegetable crops because there will be spin-offs from oilseed rape herbicides.

She said trials carried out last year, for example, showed that the herbicide benfluralin controlled a range of common Brassica weeds.