UK growers could be expecting an unachievable level of control from pre-emergence herbicides, according to experts. 

In an interview in the Sept issue of CPM, Dr Stephen Moss of Rothamsted Research says that increasing levels of resistance in blackgrass to Atlantis (mesosulfuron+ iodosulfuron) mean growers are relying more on the pre-em to provide control. 

"Stacking [herbicides] can push the level of control up, but how long can you do that? How high will you stack before the stack falls over?” he comments. 

Growers using cultural control systems as well have a lot more leeway, he points out, illustrating this with work from Rothamsted that shows how some arable establishment systems are now putting unreasonable pressure on the pre-em.

The article in CPM discusses the latest resistance findings and also puts recent dormancy results from ADAS Boxworth, funded by BASF, into context. 

The main ingredients of a pre-em programme are explored in detail, including results from HGCA-funded mixing and sequencing trials, carried out by NIAB TAG and SAC. 

There are pointers on which stacks work best, with advice from Dick Neale of Hutchinsons. “Blackgrass gets used to what you throw at it, so ringing the changes is no bad thing.” 

The Sept issue also takes a detailed look at various ways of replacing nutrients taken by the previous crop. 

“Applying this as bagged fertiliser is relatively expensive,” says Peter Dampney of ADAS. “There are other sources that are equally as effective, and which bring with them a host of other benefits. But farmers must understand what’s being applied.”

The article ranks the nutrient value, application cost and soil organic matter content of various manures, composts, by-products and wastes. 

The spreadsheet used to compile the figures can be downloaded free, exclusively from the CPM website here. As costs and nutrient value can vary considerably, the spreadsheet is a useful tool to rank materials available locally.

Other highlights of the CPM Sept issue include four user views of new combines, advice on oilseed rape herbicides and phoma and a Warwicks grower who discovers distinct benefits of putting high-horsepower tractors on tyres rather than tracks.

In-depth analysis of technical issues for the thinking arable professional, CPM is the best read arable journal delivered free to eligible UK farmers and advisors – go here to sign up, or here to download the Sept issue in full.