Oilseed rape growers can achieve a wider spectrum of weed protection this autumn by using the combined chemistry of metazachlor and quinmerac. That is according to Gemma Sparrow, Adama’s oilseed rape herbicide specialist, who advises that the twin-activity of Legion (375g/l metazachlor and 125 g/l quinmerac) delivers increased efficacy against the majority of key grass and broadleaved weeds, including difficult to control weeds such as poppy and cleavers.
“As a residual herbicide for winter oilseed rape, Legion offers excellent control of a range of common weeds,” Gemma explains. “It performs best in a pre-emergence role, but can also be used as a post-emergence treatment. Using Legion as a post-emergent allows growers to apply when soil conditions are optimal and means it can be tank mixed with a volunteer cereal spray for one less field pass, saving up to £10-15 per hectare.”
Whilst the metazachlor element of Legion provides a good base of protection against weeds including Annual meadow-grass, Chickweed, Forget-me-not, Mayweed, Red Dead Nettle, Speedwell and Shepherd’s Purse, the addition of quinmerac provides an extra level of protection against Cleavers and Poppies.
“The inclusion of quinmerac gives Legion a proven benefit over straight metazachlor by targeting a wider range of weeds,” Gemma adds. “Legion also helps to manage the resistance of weeds such as Chickweed, Poppy and Mayweed to ALS-inhibiting herbicides.”
Quinmerac is primarily absorbed through roots, but also works through contact activity for improved uptake as a post-emergent. It also exhibits improved efficacy when applied to moist soils, maximising the residual element of the product.
As with any metazachlor product, Gemma warns growers to be mindful of the need to use Legion responsibly. “Put simply, if these products aren’t used responsibly, they will be lost through the de-regulation of their actives.
“Growers should therefore follow the guidelines laid out by the Metazachlor Matters stewardship scheme which offers advice on how to protect the availability of metazachlor for future usage by preventing losses into water courses through surface runoff and diffuse pollution.
“Using Legion and other metazachlor products responsibly means reducing the amount of active ingredient applied to a maximum of 750 g/ha and restricting the timing of applications on drained fields so that no applications are made after 15th October. For fields in Drinking Water Safeguard Zones, the cut off date should be brought forward to 1st October.
“Growers should also avoid using any metazachlor product when fields are saturated or when heavy rainfall is predicted,” Gemma concludes. “Adama’s WaterAware app is a useful and reliable tool that assesses when it is safe to apply a given active ingredient. By analysing soil type and moisture data along with weather forecasts for a specific field location, the app provides a simple ‘safe to spray’ or ‘not safe to spray’ decision with regard to the timing of applications and the potential risk to surface water.”