Aphids have been known as insect pests in OSR for a long time, but during the past few years we have become aware that they are of increasing importance. This development is not limited to the UK. We see similar tendencies in Germany and other European countries. The reasons for rising populations are diverse. On the one hand aphids benefit from warmer temperatures and cover crops which provide green bridges but on the other hand the ban of NNi seed treatments leads to an earlier and faster buildup of populations in OSR, because NNIs controlled aphids in the juvenile stage of the crop.
Direct damage by aphids seldom occurs. Very high numbers of aphids are needed to impact plants and lead to reduced vigour. The higher damage potential results from the Turnip Yellow Virus (TuYV) that is transmitted by aphids (mainly peach-potato aphid and mealy cabbage aphid). Beside typical symptoms such as red coloured leaves and reduced plant vigour the virus infestation can also lead to significant yield reductions of up to 30% and reduced oil content in the seed.
There are only a few insecticides available to control aphids in OSR, but their efficacy to reduce the TuYV infestation is comparably low. The more reliable and cost effective solution is to choose a variety with resistance to TuYV. This enables the crop to tolerate a medium infestation level of aphids without risking yield penalties. Thus, an insecticide spray will only be necessary in situations of very high aphid pressure. DSV as one of the leading WOSR breeders in Europe offers varieties with TuYV resistance. Beside TEMPTATION, DSV’s first recommended variety with this novel trait, a bunch of new candidates are in the pipeline which will be ready to be marketed in the coming years.
Many experts suggest Spring rape plantings could be set to rise in 2018 with the excellent gross margin opportunities the crop brings. With crop losses possible higher than expected, due to increased flea beetle numbers, turnip sawfly, slug and pigeon damage, the increase in Phoma lesions this Autumn on untreated crops will also likely have an effect when stem canker shows later in the season.
DSV have a core base of growers who see spring rape as part of a well-considered crop rotation and who receive a very good return on investment.
How does spring rape stack up cost wise?
In 2017 spring rape was, on paper, the most profitable option for growers’ spring cropping. Treated correctly and grown in good conditions spring rape can perform well with yields of 3 – 4 t/ha not being unrealistic.
Spring crops allow flexibility in the rotation if preceding a late harvest, which is followed by poor weather conditions, and in general allows growers an excellent opportunity to sort out pernicious weed problems, such as blackgrass, while fields lie fallow through the winter. This is a key benefit compared to winter oilseed rape which offer few cultural control measures to reduce grass weed numbers and relies heavily on agro-chemistry. (the advent of Clearfield spring osr also opens another avenue for the control of broadleaf weeds)
While peas and beans offer advantages in terms of ‘free’ nitrogen, they are often difficult to fit in a rotation, and can be very poor in a bad harvest year and values can be ‘difficult’.
Seed Rate and Drilling
A key difference between winter and spring varieties is that spring rape can sometimes have a lower TGW so this needs to be considered. Growers need to careful not to drill seeds at too high a rate causing the crop to compete with itself.
Growers should aim to plant 120 seeds/sq m with conventional varieties such as Ability, 140 in poorer seed-beds, and 70 for hybrids – such as Doktrin, Makro, Mirakel and Lumen, to achieve 60-70 plants/sq m. This will achieve a thick stem and about 10 laterals – the ideal canopy structure for maximum yield
Growers should try and resist the temptation to drill too early ( February ) temperature and day length will act against the newly sown seedling. Plants will emerge too slowly and will not be able to outcompete the weed pressure and struggle to outgrow pest attack.
Drilling oilseed rape at the end of March/ early April means less pressure is put on both man and machine. Spring osr only requires 150 days to grow; therefore Phoma isn’t a problem due to its short vegetative stage and specific temperature requirements. The occurrence of fungal diseases are much less than in winter rape, so disease control is rarely necessary. However, other than phoma the main disease growers and agronomist need to be aware of, is Alternaria and Botrytis but these can be easily controlled with use of a fungicide.
Even pigeons tend to be less interested in spring OSR, as it grows so quickly and of course there are other food sources available in the spring.
Fertiliser and Agronomy
Nitrogen should be applied at the early stage of growing – about half the total, 50 -100 kg/ha, into the seed along with similar amounts of P and K and the rest should be applied at the two leaf stage. Farmers need to be cautious of applying nitrogen too late and missing the maximum plant response rate.
The strong root associated with the rape enables deep penetration and more soil fracturing than cereals. Spring rape will play an integral part in the future of farming, helping to meet new environmental and rotational requirements.
Although spring oilseed rape tends to have lower oil content than winter types, with the help of relatively high oil varieties such as Lumen and Mirakel those all-important oil bonuses can easily be reached.
The biggest barrier to success which spring rape faces is attack from pollen beetle, as the crop is often the only thing flowering once it gets going. Growers need to be checking for pollen beetle four to six weeks after emergence, once the plant has got to the green to yellow bud stage the beetle will have already done the majority of the damage. It is not uncommon to spray two to three times to help reduce pressure. Growers need to be aware that many pollen beetles are now resistant to many pyrethroid sprays used to help control them – checks should be made 3 days after treatment is applied.
Desiccation and Harvest
The application of a pod sealant can help ensure maximum harvestable yield and should be applied where possible.
Choosing a variety
DSV have a wide portfolio of spring rape varieties which include Ability , Makro, Doktrin, Mirakel, Lumen and Click CL. DSV’s Ability has been one of the marketing leading variety over the last eight years.
But due to big investments in breeding DSV has now got a wide portfolio of hybrid varieties which offer more aggressive spring growth, high seed yield and oil content as well as reduced pod shattering.
The winter Olympics have been very exciting, and notably the half pipe where Shaun White ‘the flying Tomato’ won gold again for USA. The flips and tricks he produces come at regular intervals down the pipe and are all pre planned getting more exciting over the rounds. This regularity somewhat reminds us of the spring spraying programs for cereals T0, T1, T2…… but when it comes to oilseed rape, the approach need to be a bit more ‘slope style’ and flexible. In southern areas, we are generally seeing low or no levels of light leaf spot, with pressure increasing in the north. This is a similar situation to 2017 at present - and has been verified by leaf testing.
In the treated trials at Wardington, DSV will soon be applying a prothioconazole and the first dose of fertiliser. This is done after careful planning across the DSV managed sites, taking GAI’s and undertaking SNS testing. Rates of spring N application will vary by near 100kg’s of N/ha while targeting yields of 5.5-6.5t/ha, as we are looking to improve on the 2017 YEN yield. Just as much care has been placed on the other nutrients also on a site by site basis doing tests as needed. Wardington will receiving solid Sulphur with sprays of Magnesium and Boron, while Pewsey - a being sandier site - will receive over the season solid S, Mg, P, K and liquid Boron. Boron is something we seem to be lacking across the continent which is very important at pollination.
The UK trial series doesn’t currently receive any plant growth regular so the lodging potential can be properly accessed. However PGR’s are a very usefully tool and some varieties do clearly benefit from canopy manipulation along with carefully controlled nitrogen timings.
Veritas CL, in particular, needs a PGR treatment, and whilst Phoenix CL, Dariot and Sparrow are stronger stemmed, they too will benefit from canopy manipulation from an on-label product such as Caryx. While Incentive, Compass and Dualis show little or no need of a PGR - unless on a very fertile site or sown at a high seed rate.
With regard to fertiliser timing, later applications of Nitrogen tend to suit Veritas CL, and work well with PGRs to reduce excess growth. Applications to Phoenix CL, Dariot, Sparrow, Incentive, Compass and Dualis can be earlier without problems as long as SMN and GAI are accurately assessed and appropriate rates of N established around these.
How late can we go to get the best yield and get a crop in behind is the maize conundrum and it is a careful balancing act. As to how late to go DSV cannot offer any answers but what DSV can offer is some of the highest yielding varieties at a range of maturities. DSV have an ultra-early variety Joy (FAO 150) through to an medium – late variety Petroscka (FAO 230) with LikeIt (FAO 180-190) be in the main harvest window.
At this stage the other thing we can focus on to improve the maturity of the crop is the seedbed and drill dates. It is always tempting to go early but as last year showed if conditions are not correct the maize will not grow. Ploughing and power harrowing is a very effective way to create an optimum seedbed, although it can dry out which can cause issues. However, hitting the correct timings with moisture and temperature does give yield benefits at the end of the season. At DSV we tend to favour later rather than early, but if the conditions are correct then they need to be taken advantage of.
For the first year DSV are trialling a new initiative with some of their Clearfield trial site growers who are involved with their new RDT network (Rapid Development Trials – a network of trials with over 30 growers across England) .
There are various aims which will be realised from these extensive trials - one of the first was planned after reviewing some of the work carried out by NIAB TAG in 16/17, (which was released in the Landmark Newsletter – May edition). Here, a range of mixtures were trialled, to see their effect on deterring flea beetles away from the oilseed rape plants, or encouraging them to consume the companion plants instead of the oilseed rape.
The DSV plots included oilseed rape mixed with fenugreek, a combination of cabbage crops including pak choi, a legume and clover mix and white mustard and rocket.
The results from the trial were very interesting – At NIAB’s Cambridge Hixton site whole crop failure was reported with only one exception - the white mustard and rocket mixture, where there was little or no evidence of grazing damage. The experiment also revealed positive results at their Morley site in Norfolk, where reduced grazing in the white mustard treatment was observed, compared to rape on its own or with other companion mixes.
So, after reviewing these results DSV have encouraged three of their growers to try the new idea and have included white mustard with their Clearfield crops. One of the growers mixed the seed in the drill with our exciting new variety Phoenix CL, while the other two used a slug pelleting machine to apply the seed after drilling across the trial site.
The idea is that the mustard will grow alongside the variety and help to reduce the flea beetle pressure. The mustard will then be destroyed when the Clearfield chemistry is applied – for use and guidance of Clearfield products please visit BASF’s website or contact your local area manager.
All the sites were drilled in early September so DSV are looking forward to seeing results in the next couple of week.
Figure one – Sowing date and crop damage associated with cabbage stem flea beetle grazing autumn 2016
Source: NIABTAG – Landmark – May 2017