Thinking SMART with sugar beet weed control

The 2022 season will be his second with CONVISO^® SMART. As part of a series of trials organised by breeder KWS, Billockby Farms serves as the demonstration crop for the Cantley factory area. The trials largely focus on the performance of the dedicated herbicide, CONVISO^® ONE (foramsulfuron + thiencarbazone-methyl) in comparison with a standard programme built around phenmedipham, ethofumesate and metamitron across four, 2.5ha plots.

• Plot 1: Farm standard programme comprising three sprays of: phenmedipham, ethofumesate and metamitron + oil and trifulsulfuron-methyl where needed
• Plot 2: phenmedipham, ethofumesate and metamitron f/b CONVISO^® ONE
• Plot 3: CONVISO^® ONE
• Plot 4: CONVISO^® ONE f/b metamitron, with phenmedipham if needed

The weed control has been noteworthy, observes Mr Benton. “The CONVISO^® ONE herbicide did a very good job. The residual component may have been aided by it being a wet year, but the control of fat-hen and other germinating weeds was impressive,” he says.

Come harvest and the CONVISO^® SMART crop yielded largely as expected at 5% less than the classic beet grown near-by. “The yield difference was in line with what KWS said and as is reported by the BBRO so there were no surprises,” says Mr Benton.

While he concedes that CONVISO^® SMART is yet to replace the classic beet across the farm, he remains of the opinion that the proposition of a single pass herbicide system holds great appeal.

“We had hoped to adopt the CONVISO^® SMART system following our first-year experience. This would simplify our system and ease the sprayer workload. I am still to be convinced that we can achieve this largely because we still need to make a separate spray pass for volunteer potatoes and the farm’s standard herbicide programme works out to be a little cheaper,” he says.

The difference in system costs largely comes down to the ease with which the weed burden can be controlled and the expense at which it is achieved. In a typical year, three sprays of phenmedipham, ethofumesate and metamitron + oil are the minimum. In some situations, the use of triflusulfuron-methyl is required, and where volunteer potatoes are present, clopyralid is applied.

“The combined seed and herbicide costs of the CONVISO^® SMART system, including a separate spray for volunteer potatoes, comes to about £473/ha after adjusting for a seed rate of 1.15 units/ha. This is about £15/ha more than comparable spend in the classic beet comprising seed and three passes of phenmedipham and metamitron + oil and a spray of clopyralid.”

Of the 260-hectares of sugar beet sown in 2022, 65-ha will be CONVISO^® SMART (including the 10-ha as part of the KWS trial).

The herbicide strategy will again seek to compare CONVISO^® ONE with the farm standard. The KWS trial will follow a similar programme to past seasons, but the farm's own crop has received a pre-emergence herbicide as an additional measure to afford some flexibility with the timing of CONVISO^® ONE application.

“In many respects I am pro-CONVISO,” says Mr Benton. “The varieties perform well and show good vigour and it is clear that standard herbicides, even at low doses, check crop growth. On the other hand, the yield penalty is 5% and the system costs more than we otherwise spend. If our classic beet were to require rogueing, tractor hoeing or a pass with a weed wiper, then the difference would be considerably smaller,” he says.