Pay attention to grassweed control this autumn

• High weed burden from last year

• Good control vital for good yields

• Integrated approach gets results

Farmers should pay close attention to grassweed control this autumn – with high levels of weed seeds remaining after last season.

Extremely wet conditions severely challenged cereal weed control last year. Saturated fields led to delayed or compromised application timings – allowing grass weeds and wild oats to establish strong footholds.

Weed burden

Good control this time around is vital for growers to get on top of what is a very high legacy weed burden, says Ruth Stanley, UK manager for off-patent manufacturer Life Scientific.

“The upcoming weeks after drilling offer a critical window for farmers to apply herbicides and target remaining grass weeds and wild oats before winter sets in,” she says.

Uncontrolled weeds will have a knock-on effect later in the season autumn – and ultimately at harvest. The challenge has intensified as pressure to drill early competes with the reality of late-flushing blackgrass.

Competition

“The key is to prevent the crop and weeds competing at the same time – so it is important to make sure every product works as well as possible – don’t rely on just one herbicide stack or sprayer pass and make use of all application timings and actives.”

When it comes to post-emergence options, Mrs Stanley recommends applying a single application of 0.4 kg/ha Niantic with adjuvant 1.0 l/ha Probe to small, actively-growing weeds between one and three leaves.

This should be done when the majority of the weed population has emerged, she adds.

Niantic contains 30 g/kg mesosulfuron-methyl + 6 g/kg iodosulfuron-methyl-sodium. It is a reverse-engineered herbicide formulation based on the reference product Atlantis WG.

Approved for use in winter wheat in the autumn, Niantic controls susceptible blackgrass, ryegrass, wild oats, meadow grasses, common chickweed and mayweeds in winter wheat.

“The active ingredients of Niantic are ALS-inhibitors which affect cell division so the product is most effective when weeds are small and actively growing,” explains Mrs Stanley.

Resistance

“This means It can be applied from autumn until early spring when the wheat has two leaves (GS12) up until flag leaf ligule just visible (GS39).”

Populations of blackgrass and Italian ryegrass with varying levels of resistance to ALS herbicides are widespread in the UK.

“Niantic must therefore always be used as part of an integrated approach to weed control involving rotation, cultivations, stale seedbeds and delayed drilling.”

Niantic should also be used with an authorised adjuvant and sequenced with alternative modes of action such as the pre- or early post-emergence herbicide, Firestarter which contains flufenacet and diflufenican.

Best approach against wild oats

A NIAB survey sponsored by Life Scientific looked at wild oat resistance in Avena fatua (spring wild oat), which tends to germinate in spring, and Avena sterilis ludoviciana (winter wild oat) which tends to germinate more in autumn.

While winter wild oat showed higher levels of resistance than spring wild oat in the NIAB work, most populations still showed good susceptibility to herbicides containing mesosulfuron-methyl and iodosulfuron-methyl-sodium such as Niantic.

“If you have wild oats on your farm, hopefully seed has been collected and tested, as knowing the species present can help target the best approach to control the weed in your fields,” says Mrs Stanley.