Due to the shortage of cereal straw this year, some growers are baling rape straw instead of chopping it. However, if you used AstroKerb as a herbicide on rape in the autumn/ winter, the straw cannot be used as animal bedding, says Corteva, the agricultural division of DowDupont.

AstroKerb contains propyzamide and aminopyralid. It is the addition of aminopyralid which is the issue here as it has been shown to be very persistent. (Growers may be aware of the product Forfront T which is a herbicide used on grassland. This also contains aminopyralid, and there have been failures in the following crops when muck from livestock feeding on grassland treated with Forefront T has been spread in the next season).

Warnings from the AstroKerb label:

The product must not be used on land where vegetation will be cut for animal feed, fodder or bedding nor for composting or mulching within one calendar year of treatment. Following crops (winter and spring wheat) should not be planted within 30 weeks of application of AstroKerb.

AstroKerb contains aminopyralid, traces of this material in oilseed rape straw can damage sensitive crops. Aminopyralid residues in plant tissues which have not completely decayed may affect succeeding susceptible crops e.g. peas, beans and other legumes, sugar beet, fodder beet, carrots and umbelliferae, potatoes and tomatoes, lettuce and other compositae.

Therefore following good agricultural practice ensure that all remains of the oilseed rape crop have completely decayed before planting susceptible crops.

  • Do not remove oilseed rape straw from the field unless it is to be used for burning for heat or electricity production.
  • Do not feed animals with treated oilseed rape straw.
  • Do not use oilseed rape straw for animal bedding.
  • Do not use oilseed rape straw for composting or mulching.
    Take care to avoid local overdosing.
  • Do not make more than one application of AstroKerb to any one crop.
  • If animals are inadvertently fed or bedded on oilseed rape straw treated with AstroKerb, do not use animal waste for composting.
  • Do not use on crops grown for seed.

This would also apply to Ralos – a less widely used herbicide which contains metazachlor, aminopyralid and picloram.

Thoughts for next season:

Belkar herbicide is a novel post-emergence, autumn applied herbicide for use on winter oil seed rape. With a wide window of application, thus allowing the crop to establish, Belkar provides superior control of a wide range of broad-leaved weeds, including Cranesbill, Cleavers, Poppy, Shepherds purse and Fumitory.

Belkar contains arylex and picloram so there will be no straw restrictions if this was used instead of AstroKerb in future years. A full launch of Belkar is planned in 2019, however in the meantime a small quantity will be available to farmers this year via Corteva Agriscience distribution channels.