We know that growing oilseed rape can be challenging so we have gathered together everything you need to know about oilseed rape here. From establishment to harvest we can provide insight about crop management and protection to help maximise yields.
Posted 3 months ago
August
Across much of England, most crops have been harvested, with only northern areas and Scotland to be completed during August. As we start the month, the continued dry weather and very low soil moisture is posing challenges for drilling.
Drilling by soil moisture rather than calendar date will be crucial this year. There is no point in putting seed into dry soils since this will hinder crop establishment, regardless of Cabbage Stem Flea Beetle (CSFB) populations.
Variety choice is also important for early drilled crops. Early vigour will ensure crops emerge and grow away from flea beetle quickly, but avoid varieties that also produce large canopies before winter. DEKALB’s DX Exstar and DX Excited hybrids are good examples that have good early vigour, but reduce the risk of excessive development before Christmas.
When sufficient rain arrives to drill, ensure good seed-to-soil contact and an even depth, to get crops away as quickly as possible. Nutrition is also important, and early applied nitrogen and phosphate can support good establishment.
The focus at drilling should be on creating a more resilient plant, rather than controlling flea beetle, so seed rates should be kept low. Target 30-40 plants/m2 after winter, working seed rates back to consider likely in-field losses. For hybrid varieties this equates to drilling 50 seeds/m2. This plant population range will give plants the space to branch and, with thicker stems, makes the plants more resilient to any flea beetle larvae attack in the spring. Higher populations lead to thinner stems and have not been shown to increase crop survival under flea beetle attack.
Follow best practice advice on controlling flea beetle if this is required, and be aware that there is a high level of resistance to pyrethroid insecticides, which are the only chemical option. Set traps and monitor them weekly. Only spray if you reach threshold numbers of flea beetles, and monitor efficacy. Don’t repeat a spray if you receive a poor result, since it is likely to be caused by resistance.
It’s also important to be vigilant for disease, even at drilling time. Pay attention to neighbouring fields of oilseed rape this harvest. Light leaf spot spores can be spread by wind and dispersed to nearby fields as newly drilled crops emerge, leading to immediate infection. Early drilled crops are at the highest risk as they are exposed to spores for longer.
Priorities now:
July
Harvest will begin soon as crops reach maturity, particularly in the south and east. Judging when to apply glyphosate to desiccate the crop is important, to ensure crops reach maturity before spraying and maximise yield, and not too late and risk losses from pod shatter.
Varieties with built-in pod shatter resistance (such as Dekalb varieties) will prevent some seed shedding in wind and hail and offer a degree of flexibility in the timing of desiccation sprays.
Samples should be taken from representative areas of the field, not just the edges, since there is considerable variability within fields and between fields. Ideally, sample 20 pods from areas of the crop that hold the majority of the yield.
Look for seed colour change in the pods. When the majority of seeds have changed from green to brown, seed maturity is around 30% and ready for spraying.
To achieve good desiccation, pay attention to spray quality for optimum coverage and canopy penetration.
Water volumes of 200 – 250 L/ha will help in thicker crops, and using a low-drift formulation of glyphosate, such as products from the Roundup range, will help prevent non-target damage when using higher water volumes.
Spraying earlier in the day when the relative humidity is higher will also help the spray to better penetrate the crop. Where spray timing isn’t optimal, Roundup is formulated to work better than generic glyphosate formulations in hot and dry weather, and is also rainfast in one hour.
A pre-harvest glyphosate application will also remove any remaining weed populations, particularly difficult to control grass-weeds, before harvest.
After spraying, it’s important to be patient and wait for pods and stems to be fully fit for combining., Usually this is a minimum of two to three weeks, depending on the weather.
Growers planning to drill towards the end of July should consider soil moisture as their driver, rather than the calendar date. Very dry soils will hinder crop establishment, regardless of Cabbage Stem Flea Beetle (CSFB) populations. Hold off from drilling if soil moisture levels are not optimal.
Variety choice is also important for early-drilled crops. A slower-developing variety is more suitable for this period, since those fast developers are likely to get too large, too quickly, before winter.
Priorities now:
June
At the end of May oilseed rape crops are in varying stages of flowering, with most coming to the end of their flowering period, depending on location.
The focus for June will be the build up to seed maturity and judging when to apply glyphosate to desiccate the crop.
Spraying at the right time is vital for effective pre-harvest desiccation. Spraying too early will result in loss of yield but spraying too late increases the risk of pod shatter.
Dekalb varieties, and some other hybrids, have in-build pod shatter resistance which prevents some seed shedding in wind and hail and offers a degree of flexibility in the timing of desiccation sprays.
To judge seed maturity, get into the crop and walk fields to take samples. Don’t just sample from the edges of the field, since there is considerable variability within fields and between fields, especially where earlier pigeon attack hindered canopy development. Ideally, sample 20 pods from areas of the crop that hold the majority of the yield.
During sampling, look for seed colour change. When the majority of seeds have changed from green to brown, seed maturity is around 30% and ready for spraying.
When spraying, pay attention to spray quality for optimum coverage and canopy penetration. Using water volumes of 200 – 250 L/ha will help in thicker crops. Then benefit of low-drift formulations of glyphosate, such as products in the Roundup range will also aid coverage of the crop.
Spraying earlier in the day when the relative humidity is higher will help the spray to better penetrate the crop. Where spray timing isn’t optimal, Roundup is formulated to work better than generic glyphosate formulations in hot and dry weather, and is also rainfast in one hour.
A pre-harvest glyphosate application will also remove any remaining weed populations, particularly difficult to control grass-weeds, before harvest.
After spraying, it’s important to be patient and wait for pods and stems to be fully fit for combining., Usually this is a minimum of two to three weeks, depending on the weather.
May
May sees the continuation of flowering and pod development, though where crops suffered heavy pigeon damage over winter there may be significant variation between and within fields. If May weather remains relatively dry and war, the flowering period will be extended.
May usually marks the mid-flowering period and crops will usually have received a fungicide spray to protect against Sclerotinia, however the extended dry period in April and early May means that the disease risk has been low and fungicide applications may have been delayed. If the weather turns wet, the risk of Sclerotinia infection will increase rapidly
It’s important to apply a fungicide in good time as they only provide protectant activity, and with high forward prices, it is worth protecting yield. AHDB’s Sclerotinia infection risk alerts can be used to support decisions on fungicide timings.
The recent warm weather will also have increased the development of any light leaf spot infection on the leaf canopy and the stems. Any wet weather will help to spread the disease through rain splash and infect developing pods.
When planning a fungicide application for Sclerotinia, it’s worth ensuring that it also provides protection against light leaf spot. 0.75 L/ha of AviatorXpro protects against both diseases and offers good resistance management with two actives.
Most fungicides will provide around three weeks’ protection from Sclerotinia and light leaf spot. If the flowering period is prolonged, and depending on when the first Sclerotinia spray was applied, growers may need to consider a second application to prolong protection until the end of flowering and protect yields.
If only one application of AviatorXpro or another SDHI has been made to the crop, another application can be made. Otherwise, Proline is a good alternative up to the maximum total dose per crop.
Priorities now:
April
Warm weather towards the end of March means that most oilseed rape crops are now moving rapidly through growth stages, from stem extension to green bud and flowering.
At green to yellow bud stage the focus will be on pollen beetle. Growers should monitor beetle numbers against thresholds and spray only if these are reached, to prevent significant bud damage and yield loss. However, once the crop starts to flower, pollen beetles become beneficial pollinators and should not be treated.
If an insecticide is required, it should be noted that there is widespread resistance to pyrethroids in pollen beetles. Other insecticide options are available and should be considered.
Many crops may already have received a spring fungicide spray for Light leaf spot, but stem extension onwards is a key time for disease spread through rain splash, so growers should monitor for and spray at the first sign of infection. Proline is an ideal choice for this time of year.
As soon as crops come into flower, the risk of Sclerotinia needs to be considered. A fungicide application, early-mid flowering, before significant petal fall is advisable and AHDB has started to provide weather-based Sclerotinia infection risk alerts to support decisions on fungicide timings.
A three-quarter dose of most fungicides will offer protection against Sclerotinia for up to three weeks. AviatorXprooffers excellent disease control of Sclerotinia and Light leaf spot, with two active ingredients supporting good resistance management and useful physiological effects. In recent Bayer trials and in the absence of disease, Aviator showed an increase in yield.
Priorities now:
