Early season cleavers control can deliver a 2t/ha yield benefit

UK - January 08, 2010



By starting their broad-leaved weed control programme earlier this spring, growers could save themselves from significant yield losses in winter cereals this season according to Dow AgroSciences.

A mean of four years of trials looking at cleavers control between growth stages 30 to 39, suggests that a loss of 2.2 tonnes per hectare can be expected in winter wheat by sticking with later weed control programmes.

Dow AgroSciences' Customer Agronomist Stuart Jackson believes there is still a mindset among some growers to leave cleavers control until late in the season, stating: "Cleavers is the most competitive weed in cereals and even one plant per square metre can lead to as much as a three per cent yield loss."

Looking at this season in general, Mr Jackson says that dry seedbeds in the autumn resulted in reduced broad-leaved weed control from the pre-emergence herbicides and delayed the black-grass emergence, reducing the opportunity to apply Atlantis (mesosulfuron + iodosulfuron) in the autumn. "It's likely that cleavers and other weeds will have fared quite well in those conditions and they could pose a considerable threat this season," he suggests.

However, Mr Jackson highlights two weed control strategies that growers could adhere to this spring to maximise returns from their 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, then it's possible to mix in 50 or 75ml/ha of Boxer (florasulam) and apply it as soon as active growth begins at the end of February or early March.

"If you are going through with a sprayer anyway for an application of Atlantis, putting Boxer in at 50 or 75ml/ha is cost-effective and doesn't complicate the tank mix. It tank mixes well with no additional restrictions to the following crop beyond those of Atlantis."

For the second scenario, Mr Jackson says that those in non-wheat situations (i.e. winter barley), or for those that did apply Atlantis in the autumn, a T0 timing of Boxer at 100ml/ha, or a T1 timing of Starane XL (florasulam + fluroxypr) at 1.25l/ha, will ensure that the cleavers are controlled before they compete with the crop at GS32 onwards.

If, at the T0 timing, the cleavers are still blue in colour, he advises growers to either increase the Boxer dose rate 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 show that Boxer (at 100ml/ha), applied in March, produced a 2.2t/ha yield benefit (8.8t/ha) compared with a late-season product applied in May (6.6t/ha).

In earlier (2005-2006) Dow trials, with fewer (37) cleavers per square metre, and with an untreated yield of 5.25t/ha, Mr Jackson says that Boxer applied at GS30 yielded 8.96t/ha, compared with a late-season product applied at GS39, which yielded 7.16t/ha.

"It's clear to see that typically, 2t/ha was lost between GS30 and GS39. We're definitely seeing a yield benefit by attacking cleavers early," continues Mr Jackson. "Early season applications before GS32 consistently produce a better yield and subsequent margin over input than a late-season application."

Mr Jackson concludes: "GS32 onwards is when cleavers really start to compete and this is when we see the crop yield beginning to drop off if left untreated to the later timing. Whatever you do for cleavers control this spring, get it in the tank by GS32," he warns.