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Winter oilseed rape is good break crop for tillage farmers, given its suitability to the Irish climate and our production systems.
Teagasc research has shown that including oilseed rape in the rotation can deliver a yield benefit for the subsequent cereal crop of anywhere between 0.5t/ha and 1.5t/ha, due in part to disease breaks, improved soil health and control of problematic grass weeds.
August has been a poor month for weather but ground conditions are reasonable in many areas so now is the time to start planting. Earlier planting allows the crop to capitalise on autumn growth.
Here are some top tips worth remembering when planting your oilseed crop.
Field section
Consider where winter oilseed rape fits in with your rotation and target those fields which are furthest out from a break crop. Pay close attention to recent husbandry, especially where cover crops containing brassicas were used.
Sowing date
Seedbed quality is essential, but sowing date is important too. Where conditions are right, sowing from mid-August to early September will give your crop a good chance to get established and get away. However, we are seeing some very wet conditions in select places so pick your fields carefully.
Fertility
Aim to get some organic fertiliser such as pig or poultry manure applied ahead of planting. This should be incorporated after application, with poultry manure ploughed down straight after. This will help ensure no nitrogen is not lost but take care with rates when growing hybrid varieties in order to avoid excessive autumn growth.
Remember, high pH for rape is important, up around 6.8. It is also important to have adequate P and K in the seedbed because oilseed needs this to grow in the back end.
Varieties
The recommended varieties are Anastasia, DK Extrovert, PX113, SY Harnas, Alizze, Aquila and Dariot. Some may also need to consider Clearfield varieties such as Phoenix CL or Impression CL where brassica weeds are a big problem.
Growers should also consider variety qualities other than yield such as standing ability, disease resistance, etc, before making their variety choice.
Establishment
Ploughing will help create a fine, firm and clean seedbed but direct drilling using a subsoiler can also work well. Ensure that there is enough of a tilth created when using a subsoiler to allow the seed to germinate.
Seed rates
Depending on seedbed conditions, aim for seed rates of around 35 seeds/metre squared for hybrids and 60-80 seeds/metre squared for conventional varieties. When planting Clearfield hybrids, the seed rate might be slightly lower, say 30-35 seeds/metre squared. A slightly more open crop is useful for herbicide timing and these varieties tend to have weaker stems.
Pest control
In the absence of neonicotinoid insecticides, all crops are more susceptible to flea beetles. Check your crops regularly at the early establishment stage for damage and apply a pyrethroid insecticide if numbers are high. Keep an eye on slug populations by placing a slate flat on the ground and monitor numbers
Weed control
Grassweeds, cleavers and volunteer cereals have the potential to drown out a newly emerged crop. If these weeds are present then a pre-emergence or early post-emergence treatment is the most effective strategy. It is important to know the field’s weed history for this reason.
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