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Strategies for Managing Glyphosate Resistant Weeds on Your Farm

There are a number of strategies that can be implemented to manage Glyphosate and other chemically resistant weeds. There are also important strategies that should be used to minimise potential resistance in weed populations forming if it isn’t currently on your farm. Strategies can include double knocks, cultural practices and mechanical practices.

Double knock strategies

Double knock refers to two sprays of weeds approximately 7 days apart. Double knocks can consist of paraquat-paraquat or glyphosate (Group M)-paraquat (Group L), it is always important to mix/rotate MOAs so if weeds are tolerant to one MOA they will be taken out by the other. Using glyphosate in the first spray and paraquat in the second should take out any survivors of the glyphosate spray, full label rates should always be used. Depending on the weeds present in the paddock more specific broadleaf sprays (for example 2,4 D (Group I)) could be incorporated or paraquat+diquat mix used instead of a paraquat only.

Cultural practices & Mechanical control

It is always important to minimise weed competitiveness and hit them with a non-chemistry control as well, the greater mix in control tactics reduces their chance to adapt. There are a range of weed management options to minimise resistance forming which include cultural practices and mechanical controls to reduce weed numbers and their competitiveness in the paddock, these include:


Cultural Practice:

  • Strategic tilling

  • Double knock

  • Rotate herbicide Mode Of Action (MOA)

  • Apply herbicides at label rates

  • Rotate crop and variety.

  • Cut for hay

  • Crop and pasture topping

  • Graze

Increase Crop Competitiveness:

  • Crop and variety selection

  • Crop spacing

  • Sowing time

  • Crop row orientation (sowing North – South)

  • Soil fertility

  • Disease and pest management


Harvest Weed Seed Control:

  • Narrow windrow burning

  • Chaff tramlining

  • Chaff carts

  • Bale direct

Always monitor weed populations and don’t forget that if reduced efficacy is observed in the paddock after sprays, perform herbicide resistance tests to determine the most effective control.If there are any concerns with resistant weeds on your farm please consult with your Western AG  agronomist today on how best to manage.

Article produced by - Adrik Wright, Western AG Ballarat

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