Normally, oilseed rape would be the follow-on crop from winter barley in most tillage rotations. But this has not been a normal year.
With the acreage of winter barley well down in 2023/2024, as a consequence of the poor planting season last autumn, spring barley will be the entry crop on many farms this time around.
One obvious consequence of this is a later sowing date will be achieved. The end of August is the usual cut-off date, where oilseed rape is concerned.
But given the vagaries of the 2024 harvest, a significant number of crops will have a September planting date in the context of the new growing season.
However, one upside to all of this is that weather conditions may play fair in allowing growers to prepare excellent seed beds into which they can sow their rape crops over the coming days.
“The aim is to establish a target population of 25 to 35 plants per square metre next spring,” confirmed Teagasc tillage specialist, Ciaran Collins.
“Advice often focuses on getting eight leaves before the end of autumn growth.
“Backward crops in the spring will have an inadequate number of leaves and branching sites to fulfil yield potential.
“Location and aspect are critical factors if sowing later than normal; sheltered sites further south have an advantage and high yielding crops have been achieved from mid-September sowing dates.”
Sowing oilseed rape
However good seedbed conditions is the most important factor regardless of sowing date.
Research has shown that all establishment methods can be successful, but seedbed conditions must be good to get good establishment of the crop.
Achieving an adequate seedling population ensures the crop forms an effective canopy to capture light and compete with weeds, and an effective root system for uptake of water and nutrients.
“It is advisable to increase seed rate from 50 seeds per square metre to 60 or 70 seed per square metre, if sowing is delayed,” Collins continued.
“Growers should make use of organic manures. Oilseed rape is very efficient in the utilisation of autumn nitrogen and organic manures are an ideal source and will help establishment.”
According to the tillage specialist, the best broad-leaved weed control comes from pre-emergence use of products containing metazachlor (Katamaran Turbo, Butisan, Legion etc.).
“Post-emergence options are available if needed, however, it is crucial to control volunteer cereals as they are highly competitive and will reduce plant population if present,” Collins added.
“Finally, growers should be aware of the impact that slugs can make on newly established oilseed rape crops.
“Populations are high this year so fields with a history of slug damage should be monitored; all crops should be monitored, post sowing.”