Managing Glyphosate Resistance

Glyphosate resistance is becoming increasingly common in southern NSW. It generally begins on fence lines and then spreads into the paddock during the harvest process.

Managing Glyphosate resistance requires the use of multiple techniques, such as alternative knockdown herbicides from different herbicide groups, pre and post emergent herbicides, as well as cultural methods such as cultivation, hay cutting or burning.

Paddocks where Glyphosate resistance is present may require slightly different management in preparation for sowing. Following are some rules of thumb for managing Glyphosate resistance:

• Where possible avoid dry sowing and use Paraquat as a knockdown herbicide.

• For problem areas consider using products such as Amitrole T or Alliance as a knockdown.

• For wheat stubble use a hot burn. This will destroy some weed seeds and prevent soil applied herbicides from becoming tied up on stubble.

• Apply pre-emergent herbicides to bare ground.

• Avoid mixing Trifluralin with knockdown herbicides.

• Where Sakura is to be applied, aim to spray and sow prior to rainfall, to ensure that the herbicide is washed into the root zone.

• Try to apply Triazine products prior to rainfall to ensure that they are washed into the root zone.

• Where possible, delay sowing to achieve a knockdown of early germinating weeds. However, try to sow these paddocks before the soil temperature drops too much due to shorter days. Crop competition is one of the most important factors in managing weeds. Later sown crops are slow to emerge with poor early growth, resulting in less competition with weeds.