Coping with weather challenges for spring grass weed control

This season’s weather challenges will have a knock-on effect for spring weed control strategies, in both autumn sown crops that have survived the wet winter and the large area of planned spring cropping, warns Syngenta grass weed specialist, Georgina Young. 

Grass weed populations are reported to be widespread and advanced in many crops where pre-emergence herbicides were compromised in the autumn. 

Syngenta research with NIAB shows these larger weeds are likely to be highly competitive going into the spring - and expected to produce far more seeds if allowed to grow through to harvest. 

Overwintered weeds are the priority for AXIAL® Pro applications as soon as ground conditions permit travel and the weeds are actively growing. 

Application on target

With time of the essence and field work stacking up waiting for dry weather, taking advantage of any spray window is essential. Syngenta application research has highlighted results with AXIAL® Pro can be optimised when the crop is still relatively small and weeds openly exposed by using angled nozzles applying medium to coarse spray pattern in a water volume of 100 litres per hectare.

If application is further delayed, however, and the crop has closed over with the weeds beneath, then a switch to a coarser droplet from the 3D ninety angled nozzle, applying 200 l/ha, will give greater penetration and be more effective at targeting the weeds. 

Utilising the Syngenta Spray Assist App will guide operators through the process of selecting the best available nozzle and application advice in any given situation.

To further make use of spray windows this season, tank mixing AXIAL® Pro with a compatible broad-leaved herbicide can target a wider weed spectrum in one hit, with a number of options available.  

If herbicide sequences are being used, guidelines must be followed, where grass weed control with AXIAL® Pro should be the first priority to give greater flexibility and more timely removal of the competition.

Spring barley break

The spring barley area is expected to be at the maximum  for available seed this season. Spring cropping typically gives greater opportunity for grass weed control over the winter, however wet weather has seriously compromised stale seedbed opportunities. 

Syngenta grass weed trials have shown that, even after a stale seedbed, an uncompetitive spring barley crop where grass weeds are not controlled, can result in a greater weed seed legacy, which is significantly worse than comparable winter cropping. 

Early removal of grass weeds, in particular ryegrass and wild oats, with AXIAL® Pro, will give the crop a better chance for clear growth, and limit the seed return for future crops.