Focus now on overwintered grass weeds

January 31, 2024 3 min read Syngenta

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31 January 2024, UK: Extremely challenging conditions for crop establishment in the autumn left some growers with less than 20% of their cereal area treated with pre- or post-emergence grass weed herbicides.

Coupled with that, successive periods of mild wet weather into the winter triggered repeated germination flushes of dormant grass weeds in wheat and barley fields, warns Syngenta Technical Manager, Georgina Young.

“Spring grass weed control strategies using Axial Pro are now a priority to remove competition at the earliest opportunity and enable crops to grow away quickly,” she advocated.

Syngenta grass weed research with NIAB has proven the benefits of an early focus on grass weed removal, to target larger and more competitive overwintered wild oats and ryegrass.

In addition to the greater impact on crop yields, these overwintered weeds have also been shown to produce huge higher numbers of viable seeds at harvest that will perpetuate grass weed populations, compared to later germinating grass weeds in the spring.

“Delaying application to later in the spring, to allow more grass weeds to germinate, makes the successful control of the larger overwintered grass weeds harder and more expensive – requiring higher rates and even greater attention to detail to ensure applications hit the target,” advised Georgina.

“Early removal of overwintered grass weeds with Axial Pro, followed by a later application using an alternative non-ACCase mode of action to remove later spring germinating weeds provides a robust resistance management strategy in wheat.”

With extreme wet weather this autumn and winter having depleted residual soil nutrients, early weed control can avoid further losses to grass weed competition, enabling the crop to make full use of applied inputs.

Find out more about integrating Axial Pro with Moddus PGR to help root recovery in crops affected by waterlogged conditions

Barley benefit

Axial Pro has long proven a popular option for grass weed control in barley crops. That will be especially valuable for the 2024 season, where spring barley is destined for fields where autumn drilling was impossible or crops have failed.

Spring barley offers an integrated opportunity for effective control of overwintered grass weeds before drilling. However, in-crop control of weeds remains essential. Syngenta R&D has shown that if left uncontrolled in the relatively uncompetitive spring barley crops, grass weed populations will proliferate.

With rapid growth and development of spring barley crops, Axial Pro has the flexibility for application right through to flag leaf sheath extending stage (GS41) to achieve the optimum treatment timing and hit the maximum number of emerged grass weeds. Where larger grass weeds are present, the application rate to use is 0.82 l/ha in barley crops.