10 top tips for spring weed control
Spring crops are limited in their post-emergence armoury. So pre-emergence residual herbicides need to be applied with precision in problem fields to protect yield, keep on top of populations and prevent issues in the next crop.
During the pre/peri-emergence spray timing, the aim is to get maximum coverage with the spray and retain the herbicide in the top 5cm of the soil to control new flushes of germinating weeds that may appear over time.
Here are 10 tips to maximise spring weed control.
- Choose your crop protection carefully and make sure it is applied in the right place, at the right time.
- Incorporate a suitable adjuvant to ensure your herbicides and fungicides are working as efficiently as possible.
- Aim for the highest levels of control when applying pre-emergence residual herbicides to give crops the best start. While the majority of black-grass germinates in autumn, it only takes 12 plants/sq.m in spring crops to reduce yield by as much as five per cent and return seed at a rate of 144 million seeds per hectare.
- Use pre-emergence herbicides in problem fields in the spring to keep on top of weeds and safeguard against issues in the following crop.
- Rid lighter soils of spring germinators such as knotgrass, black bindweed and redshank as early as possible. In crops such as sugar beet and potatoes, where early establishment, free from weed competition is important, doing so is vital to protect yield.
- Employ crop rotation where necessary to crowd out weeds via competition.
- Pre/peri-emergence, choose a low-drift nozzle and aim for maximum coverage. Adding a residual herbicide adjuvant such as Backrow can help optimise soil coverage and retain herbicide and moisture in the top 5cm of soil for up to eight weeks.
- Post-emergence, aim to get as much of the active ingredient in the weed leaf as possible. Adjuvants such as Arma and Kantor improve coverage and uptake to control as many weeds as possible.
- If the weeds get particularly big, hairy, or waxy in texture, control becomes more tricky and delays due to weather or workload can exacerbate the situation. In an out-of-control weed situation, a good adjuvant should reduce drift and improve retention on the leaf, rather than allowing the herbicide to simply bounce or run off the surface. It will aid spreading across the leaf to optimise entry points, improve penetration and increase uptake.
- Sulfonylurea (SU) herbicides, in particular, benefit from the addition of an adjuvant; on a molecular level, the very small nature of the active ingredient makes it hard to wet in formulations.