Controlling grassweeds in reduced tillage systems

Farmers Guide asked Zach Reilly, a senior consultant with SAC Consulting specialising in soil management and crop production advice, and the lead facilitator for the Farming for a Better Climate project with the Soil Regenerative Agriculture Group, to share his tips for grassweed control in non-inversion cultivation systems.

Grassweeds can soon become problematic under reduced tillage systems, especially where continuous cereals are grown. The Soil Regenerative Agriculture Group – ve farmers working together to establish how best to support, enhance and protect their farm soils, as part of the Farming for a Better Climate project – recently visited a range of farms in Cambridgeshire and Su olk, to nd out more about how to stay on top of grassweeds in an arable rotation. Although the grassweed species vary, management principles remain constant and are explained in the following points.

Know your weeds

A crucial rst step to managing grassweeds is to know which weeds you are dealing with, and what their life cycle is. In reduced tillage systems in Scotland, two of the main issues can be annual meadow grass and barren brome, but perennial and Italian ryegrasses can also be problematic on mixed livestock farms. The methods used to control these weeds di er, due to their di erent growth patterns:

Annual meadow grass (AMG): This grass is found across the country and is recognised by its light green, short and tufted appearance. It poses little threat to crop yields, however, it can delay ripening and interfere with harvest. AMG has a short lifecycle of only six weeks; because of this it is often seen at various stages of its lifecycle in spring and winter crops. Control relies on the use of pre-emergence herbicides and glyphosate to tidy stubbles in cereal crops.

Barren brome: Often found where winter cropping dominates, barren brome usually creeps in from the hedges and margins at the sides of elds. It is easily recognisable due to its purple tinted leaves and drooping ower head. As barren brome does not germinate from a depth of over 10cm, ploughing has been a major part of its control to date. However, in a reduced tillage system, leaving the seeds on the surface where light aids germination can allow for the weed to be sprayed o prior to planting creating a stale seed bed.

Crop rotation

A key to managing most weed, pest or disease problems is crop rotation; however, this is particularly important when controlling grassweeds. Ensuring that the cereals which dominate crop rotations (barley, wheat, and oats) are interjected by break crops provide an opportunity to use di erent chemistry, but also di erent growth patterns so that cultural control can be used. In reduced tillage systems, potatoes are often removed from the rotation due to the level of cultivation required, so ensuring that this break crop is replaced is very important. The Soil Regenerative Agriculture Group has been trying di erent crops for the past three years, and has had success with oilseed rape, spring beans and winter beans. Alongside break crops, sequencing of cereal crops can also aid, or hinder grassweed control. Oats and barley are more di cult than wheat to selectively terminate grassweeds, so thinking about the order these crops are grown can help. The group have found that it is very di cult to remove wheat from a crop of oats, so avoiding wheat as a prior crop to oats is prudent in reduced tillage systems.

Vary the chemistry

Using a variety of chemical controls is a key step to controlling grassweeds. The Soil Regenerative Agriculture Group has found that the best control is gained using a pre-emergence herbicide, targeting grassweeds as they emerge. However, it is also important to use a variety of chemistry to select grassweeds out from a growing crop, especially for grasses which emerge in the spring or have a short life in the spring or have a short life cycle. Ensuring that chemistry cycle. Ensuring that chemistry is varied and targeting is varied and targeting weeds while they are weeds while they are small to ensure that small to ensure that they are susceptible are important steps; this will also help to prevent resistance building up in resistance building up in weed populations. weed populations. The group has also The group has also found that there is a di erence found that there is a di erence in grassweed emergence between strip tillage and direct drilling. Direct drilling usually disturbs less soil, which results in a reduced level of grassweed chitting; however, this method of establishment relies on a well-structured soil to ensure crop success. Alternative methods of grassweed control, perhaps less suited to northern conditions, include delaying the sowing date to provide a stale seed bed. Although this method is possible, it relies on the early harvest and late sowing of crops which can prove challenging in the northern climate. FG

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Herbicide approvals o er cost e ective options this autumn

Looking ahead to the autumn, and establishing new crops is always a time for a fresh approach and optimism on farm. However, this season growers have the pressure of unprecedented market volatility causing much higher priced inputs, as they look to the most cost-e ective options for pro table crop management.

that where Firestarter is applied twice in sequence and the total dose is 0.9l/ha, the rst application must be made before GS14 of the crop, leaving a minimum interval of six weeks between applications,” she says.

Firestarter has also been approved for use in spring barley at 0.3l/ha at a pre-emergence timing.

For more information on Firestarter or any other products in the Life Scienti c portfolio visit the Life Scienti c website https:// lifescienti c.com/products/ FG

Producing high quality and coste ective crop protection products that provide growers with the tools they need to farm pro tably, has always been has always been the ethos of o -patent manufacturer Life Scienti c, says its country manager for the UK and Ireland, Ruth Stanley (pictured).

“So we are delighted to announce that, from this autumn, growers will be able to use a newly approved dose rate of our grassweed and broadleaved weed herbicide Firestarter in winter wheat and barley. This new dose rate allows for Firestarter to be used as a follow-up post emergence treatment at 0.3-litres/ha, in addition to its existing pre-emergence use of 0.6-litres/ha,” she says.

Firestarter is a herbicide for grassweed and broad-leaved weed control containing 400g/litre ufenacet and 100g/litre di ufenican, in line with its reference product Liberator.

As with all of the products available from Life Scienti c, Firestarter is produced through the unique process of reverse engineering – the ability to manufacture a product that is accepted as the same as that of the reference product by the regulatory authority.

Mrs Stanley explains that this exciting approval broadens the choice for autumn weed control programmes and costs. “Firestarter can be used as a follow up treatment to Luximo, the new pre-emergence herbicide, as a cost-e ective follow up, or it can be used in an alternative product stack or on its own as both a pre and post-emergence treatment.”

“However, it’s important to note

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TOWER® is a registered trademarks of the ADAMA group. TOWER® contains 250g/L chlorotoluron, 40g/L di ufenican and 300g/L pendimethalin. Always read the label and product information before use. For further product information, including warning phrases and symbols, refer to www.adama.com/uk or call The Technical Helpline on 01635 876 622.

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