A snapshot survey of fields in England shows that blackgrass is already tillered and needs further control as soon as possible – and problem fields in Scotland will not be far behind.

The mild winter, followed by a warm February has kick-started weed growth but also created good conditions for applying a post-emergence herbicide. During field visits across the country, Bayer’s technical team has identified blackgrass that is advanced for the time of year and on the brink of rapid growth if conditions stay warm.

In one of the country’s blackgrass hot spots – Oxfordshire – Bayer’s Ben Giles reported that one or two tillering plants were seen early in the year due to the mild winter.

In the last week, the rate of growth has picked up and tillering blackgrass is common across the region regardless of the crops’ drilling date.

Even outside the main blackgrass areas, plants are well-developed. As far north as Northumberland, soils have warmed and dried so there is already extensive tillered blackgrass in some September sown wheat.

This means that despite a full autumn herbicide programme, lots of blackgrass has emerged and survived until spring. Much of it has grown from a depth of 5cm and early drilling had meant that too much had been expected from the herbicide programme to deal with the carryover of seed from last year.

Added to the poor-quality seedbed, the result is a serious blackgrass problem, said Mr Giles.

Heavily infested fields – mostly later sown crops – are candidates for being sprayed off with glyphosate to prevent high seed return into following crops.

In Lincolnshire, the benefit of drilling later into a better-quality seedbed was plain to see. Images from an October 25 drilled crop show the most advanced blackgrass just beginning to tiller and according to the local Bayer commercial technical manager, Darren Adkins, later drilled crops still have relatively small plants but in crops drilled in early October, there is already much more tillered blackgrass.

As weather and ground conditions have been mainly good, applications of post-emergence herbicides such as Monolith (mesosulfuron + propoxycarbazone) are well underway in Lincolnshire.

Completing the blackgrass programme this early means that there will be a gap before T0 fungicides. Congested workloads at this time of year sometimes mean that tank mixes of post-ems and T0 are used, which is not ideal for achieving the best control.

In Shropshire, blackgrass is also at the early tillering stage. In this region, infestations are typically smaller in number so can be harder to spot at this time of year, but small infestations can be better dealt with using patch-spraying or hand-roguing later in the season.

A post-em may be a good option if mixed grass weeds like wild oats and brome are also lurking in the crop.

The mild conditions have affected all regions in much the same way and any post-em herbicide should be applied sooner rather than later. Hitting blackgrass when it is smaller leads to better efficacy from the herbicide, resulting fewer heads and thui seeds being returned to the soil.

Application technique is essential to get the best result. Herbicides like Monolith should be applied to a dry or drying leaf in fine/medium spray quality.

Boom height of 50cm and forward speed of no more than 12km/h will help ensure the spray hits the target, said the experts.