Glyphosate Resistant Ryegrass

Annual Ryegrass with resistance to Glyphosate is an increasing problem. Rain in February and March 2012 has provided the opportunity to control a germination of ryegrass without the use of selective herbicides. It is important to monitor the results of autumn fallow sprays to ensure that ryegrass treated with Glyphosate has been fully controlled. If treated plants have not fully died, follow up treatments with a different chemical group, such as Gramoxone or Spray.Seed will be required.

Where tillered Annual Ryegrass plants around paddock borders have survived a Glyphosate application, the following strategies will assist in control and management.

• Application of a high rate of Gramoxone (2.0 L/ha) using at least 100 L/ha water

• Cultivation to control weeds and provide bare soil for application of pre-emergent herbicides

• Increasing seeding rates on the outside lap to increase crop competition with weeds

• Ensuring maximum rates of pre-emergent herbicides are used on the outside lap and into corners of paddocks

If fallow spraying has controlled existing ryegrass, but subsequent germinations have appeared before sowing, it is possible to add knockdown herbicides to pre-emergent herbicides in order to control those weeds.

Consideration must be given to the combinations of products and the requirements of each for incorporation.