A snapshot survey of fields in England shows that black-grass has already tillered and needs further control as soon as possible. CPM reports.

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 – Ben Giles reports 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.

Oxfordshire – Mid February – Blackgrass plants about to tiller

In the last 10 days, small plants like those in the picture have started to tiller.

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.

Northumberland – 21 February – Tillered blackgrass in September drilled wheat

The crop was September drilled into very heavy soil lacking ideal seedbed preparation.

 

Despite a full autumn herbicide programme, lots of blackgrass has emerged and survived until spring. Much of the blackgrass has grown from a depth of 5cm and is found in the cracks.

Early drilling meant too much was required 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.

Fields like these are candidates for being sprayed off with Roundup (glyphosate) to prevent high seed return into following crops.

In Lincolnshire, the benefit of drilling later into a better-quality seedbed is plain to see. Images from a 25 October drilled crop show the most advanced blackgrass just beginning to tiller. 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.

Lincolnshire – 22 February – Beginning to tiller in late-drilled wheat

Blackgrass plants are generally smaller in late sown wheat.

As weather and ground conditions have been 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 the West of the country in Shropshire, black-grass is also at the early tillering stage. In this region, blackgrass infestations are typically smaller in number so can be harder to spot at this time of year. Small infestations may be better dealt with using patch-spraying or hand-roguing later in the season but a post-em may be a good option if mixed grass weeds like wild oats and brome are also lurking in the crop.

Shropshire – 25 February – Tillering blackgrass in early October drilled wheat

Blackgrass is well advanced for the time of year. This field is 200 metres above sea level and in a fairly exposed location but blackgrass is beginning to tiller. Compared to Lincolnshire, the weed burden is much lower here, so the downsides of early October drilling are not as obvious.

 

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 plants when they are smaller leads to better efficacy from the herbicide resulting fewer blackgrass heads and fewer 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.