Bayer CropScience has developed a new test for resistance that will give growers levels of both target-site and enhanced metabolism resistance to its blackgrass killer, Atlantis (mesosulfuron-methyl + iodosulfuron-methyl-sodium).

Now in its seventh year of use the product was still working remarkably well, the firm’s Gilles Chevallier said at Cereals 2009. “But there are an increasing number of resistance cases, and with no new modes of action likely before 2014/15 at the earliest, it is important that it lasts.”

That meant managing the product carefully to avoid resistance building up, his colleague Gordon Anderson-Taylor said. “Knowledge is the key to developing a resistance strategy. The good thing about the new test is it gives relatively rapid feedback, and information on both types of resistance.”

Enhanced metabolism resistance was the biggest threat to Atlantis, he said. “Originally, we thought it would be target-site resistance, but in practical use, we don’t now believe that to be the case.”

So the real breakthrough was the information the test would provide on enhanced metabolism resistance. “It will be able to monitor the level of resistance, probably broken down into low, medium or high categories. Knowing the level a population has will enable the grower to tackle it better; for example, through earlier applications.”

Samples for the test could be taken up early tillering, Mr Chevallier said, with an answer available in a few weeks, which would allow plenty of time for planning the following season’s strategies. But the test couldn’t be used to influence control in the current crop, he said.

Bayer plans to validate the test in the coming season, with a launch in a broader scale the following season.

  • More stories from Cereals 2009 here