Arable

“Rip up the rulebook” and target broad-leaved weeds in February Getting the best results

Broad-leaved weeds like cleavers can be controlled much earlier in the spring, growers are advised.

There are good reasons why cereal growers and their agronomists opt for the timings they do when it comes to treating broad-leaved weeds. In winter cereals, the most common approach is to tank mix at either T1 or T2, while spring sown crops are usually left until mid-to-late tillering, typically applied with the first dose of fungicide. Dow AgroSciences cereals herbicide product manager, Dr Alex Nichols (right) says: “Our research from the past few years shows that the pattern of herbicide applications is relatively static. “Growers will be thinking that by going at T1 they have given lategerminating weeds time to emerge while, at the same time, being more efficient by tank mixing herbicides with their fungicide, PGRs and trace elements for example. “There is also a bit of a knowledge hangover caused by existing chemistry which has traditionally performed best on weeds, such as cleavers, when

Zypar is a co-formulation of Dow’s longstanding active florasulam – used in Spitfire – in combination with Arylex Active which is a new active ingredient for the control of broad-leaved weeds. It is a contact-acting herbicide and some growers took advantage of the wide application window by taking out weed populations last autumn. It can be applied from growth stage 11 through to growth stage 45 in all winter and spring cereals except oats, says Dow. But most growers will opt for spring applications to achieve market-leading control of key problem weeds such as cleavers, poppies, cranesbill, fumitory, fat hen, chickweed, brassicas and mayweeds. Dow’s customer agronomist, Stuart Jackson (right) says that for winter weather conditions are warm. “These are all valid arguments, but our Arylex Active based research is showing that the benefit in yield increase from early treatment may well outweigh the practical benefits derived from treating fields at traditional herbicide timings.”

Rip up the rulebook Dr Nichols is advocating a change of strategy and urging growers to rip up the rulebook. Trials at the company’s Wellesbourne site last year showed a 1.75t/ha yield benefit in winter wheat by treating crops in February rather than April.

cereals where a residual herbicide has been used, Zypar at 0.75-litres/ha will cover all the key weeds. If residual herbicides have not been used, or their activity has been compromised – by cloddy seedbeds for example – a mixture of Zypar with a picolinafen product such as Picona will cover annual meadow grass and broadleaved weeds. Similarly, in spring cereals where a residual herbicide has been used Zypar alone at 0.75-litres/ha will control the weeds that come through the residual herbicide. Pixxaro, a combination of Arylex Chickweed, poppy, cranesbill and cleavers were present in both trials and were totally controlled by Zypar (Arylex Active) at 0.75-litres/ha. But, the trial treated on 24th February yielded 9.33t/ha while the plot left until 24th April only yielded 7.58t/ha. “Studies throughout the world have demonstrated that removing weed competition in cereals early results in more productive tillers, more grains per ear and a higher thousand grain weight,” Dr Nichols continued. “But the opportunities to take out key problem weeds early are not always there, or when they have presented themselves, growers have decided not to act.” The arrival of Arylex Active, which

Active and fluroxypyr, offers growers and agronomists a way to be more precise in targeting specific weed challenges using its dose rate flexibility, suggests the company. It has a wide range of tank mix partners, including sulphonylureas. Rates of these products can be individually adjusted in a tank mix to meet the weed control requirements on a field-by-field basis. “Pixxaro also has a position for control of late emerging weeds such as cleavers, black bindweed, fumitory and fat hen,” Mr Jackson says. “Left uncontrolled these weeds can grow rapidly as the crop senesces and then cause hassle when harvesting the crop. Large combine headers do not want to be taking in anything other than the standing crop.” was first seen in Pixxaro EC in 2016 before being launched in Zypar last spring, is part of the reason why Dr Nichols believes growers can now genuinely challenge the status quo. “Arylex-based products have proven their efficacy in cold and variable weather conditions, so growers can carry out fieldwork targeting broad-leaved weeds in February,” he continued. “It’s undisputed that applying herbicides when weeds are smaller results in a better kill. “Plus in the context of resistance, you are more likely to achieve 100 per cent kill when targeting small weeds, meaning the likelihood of resistance evolving is much reduced. The reverse is true when targeting larger weeds.” ■

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10 www.farmersguide.co.uk February 2018

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