Sugar beet growers have quite a few headaches to deal with recently, not least of which is the lower beet price, the reduction in the sugar beet area in the UK this year plus the imminent end of EU quotas. But those who stick with the crop do so because they know how to produce high yields and to make good margins. Another benefit of the sugar beet crop that may have been under estimated is its function as a break crop for grass-weeds including black-grass and wild-oats. This is only feasible, however, if there is an effective grass-weed herbicide to use. Centurion MAX (clethodim) fits the bill.
“Sugar beet is very sensitive to early weed competition. More recently black-grass and wild-oats have become more of an issue in this crop, due to the difficulties of effective control in other parts of the arable rotation as well as weed resistance. Growers who struggle to control black-grass or wild-oats on their farm should integrate Centurion MAX into their weed control programme and so reduce weed competition in sugar beet and minimise seed weed return in following crops,” says Simon Bishop of Interfarm UK Ltd.
“Centurion MAX controls black-grass, annual meadow-grass, wheat and barley volunteers in sugar beet. Although it is an ACCase inhibitor product (fop/dim), it is active on most strains of black-grass that are resistant to other ACCase products. Following its launch last year it has taken over the position as the best ACCase graminicide – this used to be tepraloxydim. Arguably Centurion MAX now takes this top position in terms of performance, particularly as tepraloxydim is losing its approval this year.”
In trials Centurion MAX gave 98% control of black-grass and 96% control of annual meadow-grass, a weed that few other ACCase graminicides can control. In UK and EU trials it also gave good activity on rough meadow-grass, wild-oats, rye-grass species, brome species, canary grass and fescue. In sugar beet trials, clethodim gave 90% control of wild-oats, tepraloxydim gave 80% and cycloxydim and propaquizafop 85% control. “Removing weed competition early and effectively will help achieve high yields, which growers must aim for if they are going to continue growing this crop,” Simon says.
Recent screening has proven that clethodim has much less resistance pressure than other ACCase chemistry. ADAS black-grass screening work in 2013 showed that 84% of the 122 samples had a specific gene mutation Ile-1781 which conferred resistance to cycloxydim, whereas just 4% of the samples had the gene mutation Asp-2078 which confers some resistance to clethodim. Apart from intrinsic efficacy, this could be an additional reason why clethodim outperforms all other fop and dim graminicides in the field, says Simon.
“An integrated approach should be used in sugar beet, involving cultural and chemical control. Winter ploughing and use of glyphosate before drilling can be introduced and a range of products with different modes of action such as ethofumesate and clethodim should be planned. As in cereals, stacking pre-emergence herbicides should be used followed by post-emergence herbicides which should include the best graminicide, which in many advisors’ views is clethodim.”
Centurion MAX is recommended at a dose rate of 1 l/ha from when the sugar beet has fully expanded cotyledons or first leaves visible up until before row closure. It controls black-grass and cereal volunteers from the 3 leaf stage to 5 tillers, with annual meadow-grass from 3 leaves to tillering. “In practical terms it is the black-grass stage which governs application timing, with 3 leaves being the best timing.”
Centurion MAX should not be applied in situations where target weeds are under stress e.g. waterlogging, frost, natural dieback drought or other environmental conditions that could interfere with its activity.
Centurion MAX contains 120g/L clethodim and is formulated as an emulsifiable concentrate with its own in- built adjuvant and packed in a 5L container. It is recommended for use post-emergence in sugar beet and winter oilseed rape to control black-grass, annual meadow-grass and cereal volunteers. It is applied at a dose rate of 1 litre/ha in 200-400 litres of water as a fine or medium spray quality. In sugar beet it can be applied from cotyledon stage up to before row closure and 56 days before harvest. One application can be applied per crop. Centurion MAX has no LERAP.
