We shall fight them in the paddocks

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Ken Young, GRDC general manager, crop protection

When Winston Churchill gave his famous “We shall fight on the beaches ...” speech, he talked about taking the battle to every arena, whatever the cost. While the battle to defend our crops from weeds is indeed fought in every corner of our properties and at all stages of crop management, we, unlike Churchill, need to consider the cost.

At $146 per hectare weeds are costing Australian grain growers in both up-front expenditure and lost yield. They are one of the largest costs and one of the biggest influences on the management of cropping systems.

As our farming systems change, with an increase in continuous cropping and the shift to no-till and controlled-traffic farming, weeds continue to adapt and remain an ever-present threat.

Reducing the weed seedbank

The development of herbicide resistance and the emergence of new weed threats demonstrate that we, as land managers, need to be agile and vigilant in our approach to weed management.

It is only by continuing to seek new opportunities that we can work towards the goal of reducing the size of the weed seedbank.

While the term integrated weed management (IWM) has been around for many years, the practices of IWM are changing. Growers are being advised to use every tool in the box to drive the weed seedbank towards zero.

This can include everything from strategic tillage, choosing more competitive row spacing, double-knock, pre-emergent herbicides, changing sowing date, crop topping and harvest weed seed control.

The more diverse the farming system, the better and more diverse the range of opportunities to target weeds in different ways – and the less chance of weeds adapting to find the chink in our armour.

A systems approach

This GroundCoverTMSupplement highlights how weed management fits within a whole-farming-system approach.

While each region faces its own unique challenges, our regional profiles show where farming systems are evolving and how our weed management approaches are being adapted to drive the weed seedbank down (see Decide who is calling the shots and Southern growers' expanding weeds toolkit).

Profitability of the farming system is the key driver and actions that reduce the weed seedbank can very quickly translate into improved profitability. This can be made possible by improvements in crop competition and harvest weed seed control (pages Narrow rows aid the battle for living spaceFinding genetic traits behind weed-competitive crops and Beat down annual ryegrass – not your profit).

We investigate how these techniques can be applied to emerging weeds such as brome grass and how they can be managed within a stubble retention system (see Tackling the brome grass seedbank to Low rainfall grass weeds need whole-of-system strategy).

While managing weeds in the paddock is essential, we should not underestimate the importance of non-crop areas as a source of weed seed, particularly herbicide-resistant ryegrass and wind-blown weeds such as sow thistle, fleabane and feathertop Rhodes grass (Multiple tactics needed for the north and New options for southern fenceline weed control).

The future of site-specific weed management (or patch management) may bring control based on new technologies. We profile one postgraduate student who is looking at how robots can be programmed to recognise specific weeds in the field (Weed-identifying robots at your command).

The GRDC has a strong commitment to keeping growers informed of the challenges and new opportunities for weed management through national resources such as Weedsmart and insights from the Australian Herbicide Resistance Initiative. In 2017 we launched the comprehensive Spray Application Manual for Grain Growers (see 'Find the IWM answers you need' and 'Essential guide to spray application' for more useful resources).

More information:

Ken Young,
0477 705 488,
ken.young@grdc.com.au

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