KERB controls blackgrass in winter oilseed rape

Following Dow AgroSciences' guidelines for maximising the efficacy of Kerb* Flo could make all the difference when controlling blackgrass and other grassweeds
in winter oilseed rape.

Key points:

  • Propyzamide, the active ingredient in Kerb Flo, is a residual herbicide with root uptake that requires even distribution in the soil profile
  • Applications should be made to firm, moist soils with a fine tilth
  • Applications must be made to small blackgrass plants, before they tiller
  • The temptation to make early applications should be avoided
  • Increased rates should be used under warm autumn/winter conditions
  • Increased rates should be used where blackgrass resistance has been confirmed
  • Crop shading can interfere with even distribution to the soil
  • Strategic use is recommended in tank mix or sequence with graminicides
OSR Spraying Autumn Herbicide

Blackgrass is an extremely competitive weed in combinable crops. Oilseed rape presents a great opportunity to tackle this most pernicious weed by using an active ingredient that has a unique mode of action with no known resistance - propyzamide. Kerb Flo contains 400g/litre of propyzamide in a liquid formulation.

Kerb 50W, Menace* 80EDF, Precis* and Quaver* Flo also contain propyzamide.

Many years of commercial experience and extensive trials work confirms the highest levels of control of blackgrass are achieved when seedbed preparations are by minimal cultivations. Blackgrass seed germinating from below the area of the soil profile in which propyzamide is most active - the top 5cm - is likely to be poorly controlled.

A further complication is caused by cool, damp weather during blackgrass seed maturation. Seed dormancy is likely to be extended, meaning the effect from pre-emergence treatments will be reduced and the residual contribution from applications of Kerb Flo must be maximised.

Applications of Kerb Flo to winter oilseed rape can be made between the beginning of October and the end of January, once the crop is evenly established and has
reached at least the three true leaf stage. To maximise the efficacy of Kerb Flo soils must be moist to enable successful root uptake by the target weeds. Best residual
activity, and hence results, is achieved from applications to moist soils of fine tilth. Applications can be made under frosty conditions unless run-off from the soil surface
is likely.

Best results are achieved when growth of weeds, especially blackgrass and volunteer cereals, is slow but transpiration continues. In mild autumns and winters
emerged weeds may take longer to be controlled, the residual effect will be shortened and overall control may be reduced. Optimal conditions, that allow Kerb Flo to perform at its best, do not normally occur until early November.

Kerb Flo can also be used to control blackgrass and other grassweeds in winter field beans. Applications must be made within seven days of drilling, and before any crop emergence, to firm, even seedbeds. Use in winter field beans is only allowed on medium or heavy soil types with less than 10% organic matter.

There is currently no known strain of blackgrass, or any other grassweed, exhibiting any degree of resistance to propyzamide.

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