More needs to be done to differentiate between meadow brome and rye brome to prevent different agronomic practices inadvertently favouring certain species within wheat crops, said a speaker at the Crop Protection in Southern Britain conference in Peterborough.
It’s commonly thought that meadow brome is more prevalent than rye brome, with figures suggesting a ratio of 5:1. Yet there is a growing perception among agronomists that rye brome is being more regularly encountered as a weed in cereal crops than previously thought.
Speaking at the Crop Protection in Southern Britain conference, Sarah Cook, research consultant at ADAS Boxworth, said if some brome species were less susceptible to commonly used grassweed herbicides, there could be a shift in relative species frequency.
Presenting findings from trials partly funded by HGCA and carried out by ADAS and Rothamsted Research, Mrs Cook said: “Pyroxsulam + florasulam (Broadway Star) gave more consistent control of both rye and meadow brome than iodosulfuron + mesosulfuron (Atlantis). Looking at the overall mean for both species and across doses, pyroxsulam + florasulam gave 91% control, whereas iodosulfuron + mesosulfuron only gave 72% control.”
However, there was considerable variation in response of different populations of both bromes to iodosulfuron + mesosulfuron. The mean response ranged from 40-90%.”
Dr Cook also said there was some evidence that rye brome was harder to control with iodosulfuron + mesosulfuron than meadow brome, which supported the theory that rye brome appears to be more common in wheat fields than surveys of British flora would suggest.
The herbicide screening carried out during the trials involved seven populations of rye brome and four populations of meadow brome. These were then placed in pots in a warm greenhouse, ready to be treated.
There are now hopes to push forward with the research, validating the results in outdoor conditions and increasing the amount of brome species involved.
Dr Cook also highlighted that although there was no suggestion that the differences in herbicide efficacy in the research are related to evolved herbicide resistance, it remains a possibility.