Effectively Managing Weeds and Chemical Resistance

NOVEMBER 26, 2019

Herbicide resistance in today’s environment is a major issue affecting crop and pasture production across all states in Australia. For producers that are facing prolonged periods of drought, sporadic and insufficient rainfall can cause increasingly tough weeds, and this can pose a challenge if those weeds have become resistant to herbicides.

Agriculture Victoria state that Herbicide resistance occurs from the repeated use of the same (or chemically similar herbicides) for weed control in crops and pastures. The potential for herbicide resistance developing is already in the paddock (it is a naturally occurring process with the natural mutation of genes). However, this process increases rapidly with the sole reliance on chemicals and practicing continuous cropping. This is because a consistent selection pressure is placed on the weed population. The few resistant individuals in a paddock survive the herbicide, enjoy having more room to grow and set a lot of seed. This resistant seed then goes on to form a resistant population. If the same herbicide is used the next time, these individuals survive to reproduce again – eventually leading to herbicide failure. It could be said that herbicide resistance is, in fact, inevitable with many herbicide groups. However, there are strategies that can delay its onset.

Herbicide resistance has been confirmed in the following grass and broadleaf weeds across Australia – feathertop rhodes grass, annual ryegrass, barnyard grass, wild oat, windmill grass, african turnip weed, flax-leaf fleabane, paterson’s curse, tall fleabane, turnip weed, wild radish and stinging nettle.

When considering weed management options without the use of herbicides, there are alternatives that exist, and they are becoming more popular as sustainable farming practices lead the way. The use of Integrated Weed Management (IWM) is the best approach for managing herbicide resistance and for ensuring that the herbicide options we have left will be more useful for longer.

One option is the use of a ChainBar. The many chain alternatives of a ChainBar have proven to be highly beneficial for integrated weed management through zero tillage, minimum tillage and maximum tillage options. Every paddock is different and has its own set of challenges, that is where the chain options can be fully adapted to match and overcome those challenges. The ChainBar works in well with integrated weed management programs as its able to be used to mulch or incorporate leftover stubble, level paddocks and prepare seedbeds before sowing. An early summer pass with ChainBar fitted with disc chain will encourage weeds to come up early so they can be removed with another pass before seeding, allowing for a weed free seeding and no outlay for chemicals.


BROOKFIELD ChainBar’s are available in working widths from 4m to 18.5m with the option of zero tillage, minimum tillage and maximum tillage chain options available.

Contact your nearest dealer today to discuss your farming needs!

Agriculture Victoria, Herbicide resistance and integrated weed management (IWM) in crops and pasture monitoring tools.