Key Points
- These trials assessed the efficacy of a range of pre and post-emergent herbicides for the control of volunteer Italian ryegrass in winter wheat over two seasons.
- The new herbicide Othello (coded as FAR 08/01 in FAR trials) and Hussar at 150 g/ha gave over 90% control of Italian ryegrass and resulted in high wheat yields when applied at the three leaf – early tillering stage of the weed.
- Twinax at the 0.3 l/ha rate gave slightly inferior control of Italian ryegrass control with some evidence that it was more sensitive to reductions in application rate than Hussar applied at equivalent rates, particularly in the 2008/09 season.
- Full rate of Gardoprim alone or half rate pre-emergent in sequence with low rates of Sencor or Twinax gave intermediate control. Gardoprim applied at 0.75 l/ha (pre-em) significantly improved the performance of post emergent Sencor on Italian ryegrass but did not improve the performance of Hussar or Twinax. The most successful low rate sequence using Gardoprim was the sequence with Hussar rather than Twinax or Sencor.
- The new pre-emergence herbicide FAR 08/02 gave similar levels of ryegrass control to Gardoprim in the 2009 trial but was superior under the drier conditions experienced in 2008. Increasing the rate of FAR 08/02 from 0.3 to 0.5 l/ha in 2008 increased ryegrass control from 50 to 75% control, though these effects were not seen in 2009.
- Gardoprim, Sencor and Treflan are not registered for use in wheat.