Top tips for getting the most out of spring oilseed crops
It’s not too late. That’s the message for growers still considering whether to drill a spring oilseed crop this year and with the right care, both linseed and oilseed rape can give good returns.
Both spring linseed and spring oilseed rape can be drilled right up until the end of April, confirms Nigel Bazeley of Premium Crops and Richard Elsdon of United Oilseeds, who admit that the potential trade-off with delayed drilling dates can be a later harvest.
“With these crops, it’s a sprint not a marathon,” stresses Mr Elsdon. “So getting the start right is very important. Waiting until daytime soil temperatures reach 5C before drilling is sensible.”
Whichever choice you go for, seed-bed conditions are critical for success, they agree. “These are small seeded crops which need to go into a fine, firm seed-bed with some moisture, in order to get a good establishment. A bit of warmth helps, too.”
The perception of linseed is that it’s late and difficult to harvest, acknowledges Mr Bazeley. “But that’s not the case if you choose the right varieties, select your herbicides with care and make sure that desiccation is timely and efficient.”
For spring linseed, the aim is to get a lot of single stemmed plants, advises Mr Bazeley. “It’s a mistake to get too much tillering or branching.”
Early maturing varieties are essential if an early, easy harvest is preferred. “The difference on farm between an early and late maturing variety can be as much as three weeks at harvest time. And once you get into a late harvest, there are often additional costs such as drying.”
Varieties with early maturity scores include choices such as Abacus, Altess and Duchess. “And some of these are known as easycut varieties, because they have less fibre in the stem. They’re very early, with short, stiff straw.”
A fine, firm seed-bed with 1-2.5 cm of settled soil is ideal. “Drill around 650 seeds/sq m, which should give you 400 plants/sq m.”
Flea beetle can be a problem at emergence, although this hasn’t been the case for the last few years, recalls Mr Bazeley. “Our seed is all Chinook (beta-cyfluthrin + imidacloprid) treated, which helps. But a good seed-bed also means that the crop is less vulnerable to attack.”
Herbicides must be used with care, he warns. “Some are too harsh – particularly metsulfuron-based products – and will check the crop’s development, which then delays maturity and suppresses yields. Check with your agronomist and use low rate broad-leaved weed products at an early timing.”
A good choice is Chekker (iodosulfuron + amidosulfuron), which has been granted an Extension of Authorisation for Minor Use (EAMU) for use in linseed, he recommends.
The crop’s nitrogen requirement of between 100-120kg/ha should be applied in two splits – the first when the tramlines are visible and the second at green bud. Fungicide use is rarely necessary, although linseed does respond to a first flower application of a triazole, even in the absence of disease.
Yields in the region of 2-3t/ha are possible, continues Mr Bazeley. “It can be grown on all soil types, but not any further north than Yorkshire. This year, contracts have been available for linseed at around £400/t.”
Desiccation has to be carried out at a busy time, when most growers are already in the thick of their cereal harvest, he accepts.
“But it is so important. Time, care and effort will all be rewarded, as you get a much easier and earlier harvest. The idea is to have the linseed sitting and waiting as soon as you’ve completed your wheat harvest.”
Diquat is preferred to glyphosate for desiccation, as it has been more reliable. “Spray in the evening, as you get better uptake then. And target the stem, not the canopy.”
Spring oilseed rape
A proportion of the spring oilseed rape being planted this year will be following a failed winter crop, notes Richard Elsdon, technical manager at United Oilseeds.
“If that’s the case, you must burn of what’s left with glyphosate before you start. And any previous crop must be completely dead.”
Then wait until the top inch of soil is dry, or in a friable condition, before using a disc direct drill, he recommends.
“The disc direct drill has a role because you want to disturb the least amount of soil possible,” he continues. “That will reduce the amount of spring weed germination, which matters because the herbicide armoury is very limited.”
Doing cultivations could be counterproductive, he warns, as it will result in clods being brought up to the soil surface. “With a direct drill, you can work to 1-1.5cm below the surface and then tiptoe out of the field. A following Cambridge roll is a good idea.”
A residual herbicide such as metazachlor should be used in most fields if it hasn’t been applied in the autumn, he advises. “And Avadex (tri-allate) granules will give good control of wild oats, as well as confusing any blackgrass.”
Both products should be applied as soon as the rolls come out of the field, he adds.
Phosphate and potash will still be in the soil if they were applied in the autumn, points out Mr Elsdon. “If they weren’t, then 30-40kg/ha of each should be put into the seed-bed before drilling.”
Half of the 100-140kg/ha of nitrogen required should be applied before drilling, with the remainder going on once the tramlines are visible. “And don’t forget sulphur. You need 60kg/ha of SO3.”
Earliness of harvest is an important characteristic when choosing a variety, he believes. “Tamarin is the earliest on the Descriptive List, but there are others with this trait too.”
Seed treatments will help with turnip flea beetle control, with Cruiser (fludioxonil + metalaxyl + thiamethoxam) having the edge as it also offers downy mildew control. “Use a reasonably high seed rate, so that a bit of late frost loss doesn’t matter. And keeping plant numbers up helps to crowd out the weeds.”
Mr Elsdon suggests a seed rate of 5-6kg/ha for conventional varieties and 70 seeds/sq m for hybrids. “That’s one bag for 3ha.”
Pollen beetle control is really important in the spring crop, he advises. “Look for the beetle when the rosette is a decent size. They can burrow under the leaves which enclose the green bud and do a great deal of damage.”
Just two or three pests a plant are enough to justify treatment, he adds. “Once they’re in flower, it isn’t an issue.”
Resistance to pyrethroids over an expanding area mean that insecticide choices come down to Biscaya (thiacloprid) or Rumo (indoxacarb) for most growers. “If you’re worried about using a neonicotinoid spray, Rumo is from a different group of chemistry.”
Other pests to be aware of include seed weevil and bladder pod midge. “Seed weevil can be a problem at flowering and it opens the door for the bladder pod midge. A pyrethroid will be effective against both, but make sure you follow the guidelines aimed at protecting bees.”
Spring oilseed rape doesn’t have to be as dry as linseed at harvest. “Use glyphosate and a pod sticking agent before harvest. You’ll find the crop stands bolt upright, which helps with combining.”
Case study: Tom Ireland, Lincolnshire
Lincolnshire grower Tom Ireland has chalked up 20 years’ experience of growing spring linseed, using it to follow sugar beet at Helpringham, near Sleaford.
He describes it as a weather dependent crop. “The weather at flowering is critical and it’s important that it doesn’t run out of moisture, especially at the emergence stage.”
Mr Ireland normally drills the linseed crop at the end of March or in early April, when the conditions are right and warming up. “We may be a bit later than that this year because it’s still so wet. It has to hit the ground running, or flea beetle can really give it a hammering.”
Normal practice is to plough the beet land as soon as lifting is finished, so that the linseed can be combi-drilled. “That could change in 2013 as we’re growing some on stronger land than usual, where we didn’t manage to get our planned wheat drilled.”
Weed control has been straightforward in most seasons, with the exception of some polygonum species, he continues. “There are quite a few Extension of Authorisation for Minor Uses in place now, so there’s a good choice of herbicides. Of course, they’re used at our own risk.”
He finds his agronomist’s input invaluable with herbicide recommendations. “There’s a danger of crop damage, so we always follow his advice to the letter.”
Yields are around 2.5t/ha (1t/acre) in most years, continues Mr Ireland. “We harvest it in the last week of August or first week of September, after the cereals have been done. It may have been desiccated a month before that if we’ve used glyphosate, or more recently with a different choice of desiccant.”
Harvesting is nothing like the nightmare that some growers fear, he notes. “Providing the crop is ready, it’s a doddle. But you must wait for it to be fit.”
Once desiccated, linseed is quite weatherproof, he maintains. “It will wait for you, if necessary. So it doesn’t cause us any workload problems.”
He also finds that it provides the perfect entry for direct drilled wheat. “It leaves the soil in very good order and it presents us with some good blackgrass control opportunities, so it really is a true break crop.”
