A range of new hybrid herbicide-tolerant sugar beet varieties are on trial in Irish fields. The varieties are bred by UK-based KWS, who used classic breeding techniques to identify and integrate the naturally occurring tolerance to ALS-inhibitors into their breeding programmes to make Conviso Smart varieties.

The Conviso Smart system is a collaboration between plant breeder KWS and Bayer Crop Science that started in 2001. More than 1.5bn cells were screened to locate this naturally occurring tolerance.

These hybrid beet varieties are designed to be used in conjunction with Bayer’s Conviso One herbicide

These new herbicide-tolerant varieties will allow growers to tackle problem weeds with new chemistry, while also facilitating the growing of beet in weed-beet infested fields. These hybrid beet varieties are designed to be used in conjunction with Bayer’s Conviso One herbicide, an oil dispersion mix containing the ALS actives foramsulfuron and thiencarbazone-methyl.

Conviso Smart varieties prevent the ALS-inhibiting herbicide from binding with the ALS enzyme, allowing the sugar beet to continue to produce amino acids and grow.

For the target weeds and conventional beet varieties, Conviso One works by binding with the ALS enzyme, preventing the production of essential amino acids, leading to plant death.

According to the label, this gives Conviso One a wide spectrum of broadleaved weed control, including fumitory, cleavers, common chickweed and poppy, charlock, redshank, volunteer oilseed rape (with the exception of Clearfield-enabled oilseed rape), as well as non-Conviso Smart beet varieties. Susceptible grassweeds include annual meadow grass.

The timing of applications is generally later and corresponds with the second or third treatment in a conventional herbicide system

Conviso One treatment consists of one application at full rate (1l/ha) from the first-leaf visible (GS 10) up to and including the eight-leaf stage (GS 18). Alternatively, one application (0.5l/ha) may be made from the first-leaf visible (GS10) up to and including the four-leaf stage (GS14). A second application (0.5l/ha) can be made from the two-leaf stage (GS12) up to and including the eight-leaf stage (GS 18). A minimum interval of 10 days must elapse between applications.

The timing of applications is generally later and corresponds with the second or third treatment in a conventional herbicide system. This may help growers pick up later-germinating weeds like fat-hen. The product has some residual activity.

Only hybrid sugar beet varieties are available at the moment

According to the label, Conviso One can be sequenced with other non-ALS herbicides. More details on programmes will be available over the coming year. The onus will be on growers to protect this new tool. Tight management of bolters and volunteers, crop and chemistry rotation, cultural control as well as vigilance when spraying, especially when in the facility of non-Conviso beet varieties, will be vital to its success and longevity.

Only hybrid sugar beet varieties are available at the moment, but it is envisaged that hybrid fodder beet varieties will also be developed. This season, up to four Conveso Smart varieties are being trialed by Goldcrop and Terrachem in Irish fields. Growers will be able to visit these trials later in the season. It is expected that the varieties will become commercially available to growers next season.