Weed control measures have yet to be implemented in many winter oilseed rape crops.
There has been a significant trend over the last few years to use Kerb or Astrokerb to control the bulk of the weeds according to Teagasc.
However, the deadline for using these products is fast approaching – they must be applied before the end of January.
Significantly, both herbicides work well in cold conditions.
Weeds in oilseed rape are generally advanced at this stage. According to Teagasc tillage specialists, bigger plants – including chickweed – may be difficult to control.
This is despite the fact that product labels may suggest otherwise.
Growers are recommended to use 1.5-1.7L/ha of Astrokerb or 1.8 -2.1L/ha of Kerb Flo/Barclay Propyz.
Growers should note that crops treated with Astrokerb, cannot be baled for straw.
Cover crops
Many cereal growers have catch or cover crops growing in fields that will need to be managed over the coming weeks. The benefits of taking this approach include enhanced nutrient trapping through to soil structure improvements.
However, many growers can be left in a quandary as to how to destroy these crops at this time of year.
According to Teagasc advisors, there are a couple of options in this regard, all of which have pros and cons associated with them.
In addition, cover crop destruction must take place within the terms and conditions laid down with the current conditionality and Agri-Climate Rural Environment Scheme (ACRES)-related schemes.
First-off, glyphosate will kill all plants growing in the field and leave the ground ready for cultivation.
However, more and more farmers are now grazing catch crops as a means of destroying them. This approach reduces the need for glyphosate applications in many cases.
Grazing will also recycle the nutrients into the soil more quickly than if the crops are left standing, especially if the catch crop is getting stemmy.
However, if there are volunteer cereals in the catch crop and the plan is to grow spring barley, then destruction must take place 6-8 weeks before drilling.
Such an approach helps to prevent direct Barley Yellow Dwarf Virus (BYDV) transmission, if there are aphids present.
So, if a grower intends to drill crops in mid-March, then cover crops should be burned-off by the end of January, at the latest.
The main problems with grazing catch crops is firstly, the requirement to fence the ground, and secondly the potential for soil damage if the soil conditions are wet.