Getting the best from Betanal Tandem: four top tips for weed control

Sugar beet is one of the few crops that supports a wide range of effective grass and broadleaved weed control options. Even for black-grass, a scourge for those on heavier land, the pre- and post-emergence options are far from limited.

While the list of available products may be extensive, many come with strict application restrictions if crop scorch and checked growth are to be avoided. Here we identify the main considerations.

1. Application timing

Sugar beet is easily stressed by herbicide applications, especially during periods of dry and hot weather. Weeds are more easily controlled when actively growing and soil moisture levels are good.

Herbicides are best applied in the early morning when temperatures are lower and the weeds more receptive to the herbicide. Diurnal temperature fluctuations of 18oC or more will stress crops as will high daytime temperatures of 21oC or more. Herbicide applications should be avoided in such conditions.

Frosts can be damaging too. Not only do they stress the plant, but the wax layers that make up the leaf surface are affected meaning there is increased risk of yield loss if herbicides are applied during or immediately after a frost.

Betanal Tandem can be applied at a maximum individual dose of 1.5 L/ha with a maximum total dose per crop per year of 4.0 L/ha. Growers must not apply more than 1.0 kg/ha of ethofumesate per hectare in any three-year period.

2. Include an adjuvant oil

Cool and breezy conditions increase the wax layers on the beet leaves which reduces the risk of crop damage. This is also true of weeds. Where conditions have resulted in waxy leaves, include a suitable adjuvant oil, such as a methylated rapeseed adjuvant oil or methylated vegetable adjuvant oil, to support herbicide effectiveness by softening the leaf cuticle.

3. Include a suitable tank-mix partner

Betanal Tandem is compatible with a range of residuals and contact-acting herbicides for broader control of weeds. Where cleavers, common hemp nettle, knotgrass, annual meadow-grass, pale persicaria, redshank and ivy-leaved speedwell are present, the inclusion of Goltix 70 SC (metamitron) will support control. Where volunteer potatoes are present, the inclusion of Dow Shield 400 SC (clopyralid) will extend control.

Weeds controlled at the expanded cotyledon stage by a series of well-timed Betanal Tandem + oil sprays

* denotes where the addition of Goltix 70 SC will support control

4. Observe the conditions of the thiamethoxam emergency authorisation

Weed control in sugar beet has taken on added significance following the derogation granting the use of the neonicotinoid seed treatment thiamethoxam. A condition of the emergency authorisation is that flowering weeds in and around sugar beet crops must be effectively controlled as part of a suite of measures to protect beneficial insects.