Following a successful autumn for wheat establishment, finish the weed control programme early this spring before focusing on nutrition and disease control to maximise the yield potential of wheat crops.

During the recent Crop Doctor event at Bayer's weed screen in Cawood, Yorkshire, Weed Control Specialists shared their thoughts on managing crops this spring.

A strong start gives you an advantage
"We've seen the legacy of last season which was a good year for weed control.  We didn't see many weeds in the crop or a lot of seed return," says John Cussans, Weed Science Principal Consultant at ADAS.

"Every single field is different, but generally, things are looking good so far this year. In the crops and trials I have seen, the herbicides have worked really well. Another thing on our side is how well-developed and suppressive the crop canopy is looking; this will help a lot with weed management."

This is supported by results from the weed screen which showed good performance of pre-emergence herbicides against key grass weed species including black grass, Italian rye-grass and brome.

Don't let complacency creep in
Even after a successful autumn, don't take weed control for granted. By spring, residual protection will be fading plus grass weeds and broadleaf weeds will break dormancy and need controlling.

"Anything you can do to support crop growth around the nutrition programme and disease management will help keep the crop canopy healthy and support weed control. When it comes to weeds, now is the time to get out there and scout out where there was good control last autumn; and places with weed pressure that need a follow up in spring."

"Last autumn, there were quite a lot of somewhat earlier drilled winter cereals, understandably, because there are a lot of other considerations for farmers in addition to weed management. But that may have put a little bit of pressure on the pre-em. programmes and necessitate treatment in the spring."

Choose the best product for spring control
In most cases, grass weeds are the main target. "For black grass, Italian rye-grass and brome we recommend using Atlantis® Star (mesosulfuron + iodosulfuron + thiencarbazone)," says Chris McClymont, Bayer Technical Manager (North East).

"You can apply the full rate which offers 15g/ha of mesosulfuron from 1st of February as well as iodosulfuron and thiencarbazone, offering a three-way combination of grass and broadleaf weed activity.

Being able to use the full rate from start of February is crucial because targeting weeds when they are still small contributes to better control of problem weeds such as black grass and Italian rye-grass. Smaller weed size means you are delivering proportionally more active ingredient per gram of biomass overwhelming the capacity of weeds to metabolise the herbicide.

Optimum application conditions and technique
"Make sure you apply the post-emergence as early as possible when conditions allow.  The optimal conditions are on a bright day with high light intensity, field experience and glasshouse trials have shown that this helps efficacy. But you cannot always wait for perfect conditions, I would prioritise hitting weeds when they are small."

Apply Atlantis® Star to a dry or drying leaf with the correct nozzles and water volume for the target weed. Forward speeds of no more than 12 km/hour, boom stability, and the correct boom height for the nozzles being used. Typically, this is 50cm above the target for 110-degree nozzles at 50cm spacings to reduce drift and ensure as much active ingredient as possible reaches the target.