AN ADAS expert has said early action is critical in the increasingly tough fight against grass weeds.

James Clarke said in most instances early pre- and postemergence treatments will deliver superior control than those based on either “wait and see what weeds emerge” or “delay until all weed seeds have flushed”.

As grassweeds, particularly blackgrass, pose an increasing challenge, he said farmers need to use the whole array of control measures including crop rotation, cultivations and sowing date.

“However, when it comes to using herbicides, the key is a full programme and early applications,”

said Mr Clarke.

“Putting the herbicide in place before weed seeds germinate will ensure the optimum benefit from any pre-emergence treatment.”

Similarly, he said, autumn post-emergence sprays perform best when applied relatively early to small and actively growing weeds.

Not only will this control weeds, but it will also protect against yield loss as infestations compete with the crop.

Mr Clarke said there was a misconception that delaying post-emergence treatment would allow more weeds to emerge – but most grass weeds emerge in a fairly short period of time.

He said: “It is far better to get good control of the bulk of the flush early, rather than wait for every last seed to germinate and get poor control of them all.”