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Early control of cleavers boosts winter cereal returns by £200+ per hectare

Controlling broad-leaved weeds early will be particularly important this spring and could boost winter cereal yields by more than two tonnes per hectare compared with later treatment, a benefit worth over £200 per hectare, according to Dow AgroSciences.

"Cleavers is the most competitive weed species in cereals," emphasises Stuart Jackson, the company’s Customer Agronomist. "Our own trials to investigate the impact of control measures between Growth Stages 30 to 39 found that by sticking to traditional later control programmes growers reduce winter wheat yield potential by up to 2.2 tonnes per hectare. With forecasters predicting an economically-tough year ahead for farming it will be critical to take full advantage of every opportunity to optimise production.

"Many growers leave it until late in the season before they tackle cleavers, but by then the damage has been done - the crop’s yield and economic potential will have been severely reduced. The situation will be particularly acute this spring because dry seedbed conditions autumn reduced the effectiveness of broad-leaved weed control from pre-emergence herbicides and delayed the emergence of black- grass, which reduced the opportunity to apply Atlantis (mesosulfuron +
iodosulfuron) in the autumn. Under those conditions cleavers and other weeds have fared quite well and could pose a considerable threat this season."

Mr Jackson highlights two weed control strategies which growers could adhere to this spring in order to maximise returns from winter cereals by ensuring that cleavers are controlled before they compete with the crop from Growth Stage 32.

"In situations where growers will be applying Atlantis in the spring, they should seriously consider including 50 ml/ha or 75ml/ha of Boxer (florasulam) and applying it as soon as active growth begins at the end of February or in early March.

"If you are going through the crop with a sprayer to apply Atlantis, including Boxer at these levels is cost-effective and doesn’t complicate the tank mix.
Boxer tank-mixes well, with no additional restrictions to the following crop beyond those which apply to Atlantis."

The second scenario suggested by Mr Jackson is that growers who are in non-wheat situations (i.e. winter barley), or who applied Atlantis in the autumn, should apply 100ml/ha of Boxer at T0 timing, or a T1 timing of Starane XL (florasulam +
fluroxypr) at 1.25l/ha to ensure that cleavers are controlled before they compete with the crop at GS32 onwards. If, at the T0 timing, cleavers are still blue in colour, growers should either increase the rate of Boxer to 150ml/ha or wait until active growth begins and then use 100ml/ha.

Dow trials in winter wheat with high levels of cleavers infestation during the
2007-2008 season showed that Boxer applied at 100ml/ha in March produced a 2.2t/ha yield benefit, the crop yielding 8.8 t/ha compared with 6.6t/ha where a late-season product was applied in May.

Earlier Dow trials (2005 - 2006) in a crop with fewer (37) cleavers per square metre produced an untreated yield of 5.25t/ha, but Mr Jackson says that where Boxer was applied at GS30 this increased to 8.96t/ha, compared with 7.16t/ha from a late-season product applied at GS39.

"Typically, 2t/ha was lost between GS30 and GS39 and so there was a significant yield benefit by attacking cleavers early. Early-season applications before GS32 consistently produce a better yield and subsequent margin-over-input result than late-season application," Mr Jackson emphasises. "Cleavers really start to compete from GS32 onwards and this is when we see the crop’s yield beginning to drop off sharply if left untreated to the later timing. Whatever you do for cleavers control this spring, my advice is to get it in the tank by GS32."

More information on Boxer is available at www.dowagro.com/uk