Being careful with Conviso – Crop Production Magazine

While interest in the Conviso Smart system continues to grow due to being a reliable and effective weed control method in sugar beet, crop husbandry still requires the same level of detail, stresses one agronomist.

Having advised on the system – which involves planting a Smart beet variety and using a dedicated accompanying herbicide – for around five years, Farmacy’s Jack Richardson says spray timings are critical in achieving success.

Furthermore, this has been demonstrated acutely this past year, given challenging spring weather conditions. “It’s not a case of it’s easy and you can blanket spray herbicides regardless, Conviso varieties require good management.

“While the Conviso system is effective at weed control, including weed beet, careful husbandry in the crop is still required to time everything correctly. You can drill multiple fields on the same day, but due to soil type, condition and weed pressure, they’ll develop very differently,” says Jack.

Evaluating a crop of Smart Rixta KWS grown at WD Branton in Deeping Saint Nicholas, he highlights the importance of pre-emergence herbicides in preparing for Conviso beet.

“This crop received Goltix (metamitron) plus Efeckt (ethofumesate) with the purpose of buying some time. On siltier land especially, you can be waiting for weed beet to emerge and in the meantime, broadleaf weeds such as fat hen will become established and too big.”

Regarding application of the Conviso One (foramsulforon+ thiencarbazone- methyl) herbicide, Jack believes in this instance, it could have been earlier. “There’s maybe only one week in it, but once fat hen is 5-10cm tall and just above the sugar beet, it’s very difficult to control, continues to grow and competes with the crop.

“However, it doesn’t suit everyone and there are stringent stewardship requirements, such as staying on top of bolters within the crop to prevent carry over of resistant seed, as well as controlling any volunteers within following cereal crops.”

As the 2025 sugar beet campaign is now underway, the importance of accurate harvester set-up has also been highlighted. This is due to variable root size and therefore potential harvester losses and subsequent volunteers.

Despite prolonged arid conditions, initial feedback is that yields are encouraging, although there’s variability, says Andrew Dear, British Sugar’s head of technical support. “Overall, this year’s crop continues to develop well; we’re expecting good yields and sugar contents in the Wissington area.”

Accurate harvester set-up requires a skilled operator with good attention to detail, because if done poorly, the results are often highly visible, explains Stephen Aldis, BBRO head of field operations.

“Most contractors are experienced and use well-maintained machinery, so do a good job. Changing crop conditions often require harvester adjustments and this can be where issues occur such as over-crowning, broken roots and beet being lost through the machines,” he says.

Losses of this type pose a risk to future crops through the proliferation of disease, virus and soil-borne

pests, as do temporary clamps of field margins. Controlling these threats to future performance can be achieved through ploughing or spraying with Roundup (glyphosate).

Critically, where Conviso Smart volunteers emerge in the following rotation and the crop restrictions permit, these are best controlled with Group 4 herbicides, says Bayer’s Roger Bradbury. This group includes mecoprop, 2,4-D, MCPA, aminopyralid, fluroxypyr, triclopyr and dicamba, meaning there should be a range of suitable products available, he adds.

According to Roger, the use of ALS inhibitors in sugar beet isn’t new triflusulfuron-methyl, a sulfonylurea used for the control of broadleaf weeds, gained approval more than 20 years ago. However, the introduction of the Conviso Smart system and Conviso One extended use of an already heavily utilised group of active substances, he stresses.

“ALS herbicides are often widely used because of the flexibility and efficacy they bring to weed control, but changing farming practices mean increasing reliance on a reducing number of products. Cultural measures and use of alternative modes of action are vital if they’re to remain effective long-term.”

Field management ahead of drilling is often the best opportunity to control problem weeds, and an important step in reducing the risk of resistance developing, he points out.

“Effective weed control and convenience of operation are strong justifications for choosing the Conviso Smart system, but without effective bolter control, groundkeeper management and diligent use of all available herbicide groups across the rotation, growers risk compromising its versatility.”