Crop weeds: integrated weed management (IWM)

Page last updated: Wednesday, 17 June 2020 - 5:04pm

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In-crop weed competition causes losses costing around $1 billion per annum for Western Australia. There are very effective strategic and tactical options available to manage weed competition that will increase crop yields and profitability. Weeds with herbicide resistance are an increasing problem in grain cropping enterprises. The industry and researchers advise that growers adopt integrated weed management (IWM) to reduce the damage caused by herbicide-resistant weeds.

Herbicide resistant weed populations are found throughout all cropping areas of Australia from Western Australia to central Queensland. The number of resistant species and areas affected by resistance continue to increase. By understanding the implications and evolutionary processes of herbicide resistance, appropriate weed management strategies can be devised that will minimise the impact and delay the development of further resistance.

Integrated weed management (IWM) is a system for long-term weed management and is particularly useful for managing and minimising herbicide resistance.

An integrated weed management plan should be developed for each paddock or management zone.

In an IWM plan, each target weed is attacked using tactics from several tactic groups (see links below). Each tactic provides a key opportunity for weed control and is dependent on the management objectives and the target weed's stage of growth. Integrating tactic groups reduces weed numbers, stops replenishment of the seedbank and minimises the risk of developing herbicide-resistant weeds.

IWM tactics

Successful weed management also relies on the implementation of the best agronomic practices to optimise crop growth. Basic agronomy and fine-tuning of the crop system are the important steps towards weed management.

There are several agronomic practices that improve crop environment and growth, along with the crop's ability to reduce weed competition. These include crop choice and sequence, improving crop competition, planting herbicide tolerant crops, improving pasture competition, using fallow phases and controlled traffic or tramlining.

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