Bigger spray bills pay off for top oilseed rape growers

The best oilseed rape yields come from growers prepared to invest in fungicides and insecticides. That is a significant finding from analysis of the ProCam Group’s 4cast agronomy tool carried out by the firm’s Nick Myers.


By examining last season’s information from about 5000ha, grown mainly in Cambridgeshire, Essex, Suffolk and the Midlands, Mr Myers has pinpointed several other areas that helped the top 25% of producers attain that position.


Their success is shown by their achievement of a good average yield of 3.9t/ha – well above last year’s mean of 3.15t/ha. Clearly, yield counts for little if it is obtained at excessive cost. But the top 25% also turned in a gross margin of £745/ha.


CROPS table 1By contrast, the bottom 25% managed an average of only 2.28t/ha, leaving them with a gross margin of just £254/ha.


One of the first 4cast areas Mr Myers explored was variety.


The top 25% tended to grow more Castille and Excalibur – 74% of them having Castille and 11% Excalibur.


Of the bottom group, only 25% grew Castille and just 5% had Excalibur, a wide range of other varieties figuring.


With establishment often seen as key to a successful rape crop, cultivations were also analysed, and here the signs were that better yields were linked to more attention being paid.


Autocasting appeared to be more favoured by the bottom 25% of growers, though this could be a seasonal effect, Mr Myers acknowledges.


“The extended drilling and difficult conditions in autumn 2007 may also explain why more farmers ploughed than they would do normally.”


However, the real differences between the top yielding growers and the rest are down to their use of inputs, he says. This is highlighted in table 1, which shows that all three groups incurred similar variable costs, but their gross margins were markedly different.


The margin of the top group was nearly three times that of the bottom one.


CROPS table 2The dramatic edge merited further investigation into differences between inputs. And this revealed that the top quartile spent 25% less on seed, 12% less on fertiliser, but 10% more on sprays (table 2).


“One of the most interesting findings was that the 25% of farms with the highest yields were spending nearly 19% more on fungicides and over twice as much on insecticides as the bottom 25%,” says Mr Myers.


“Protecting the crop from yield-eroding diseases, such as phoma and sclerotinia, is vital if high yields are to be achieved.


“Similarly, keeping insect pests from attacking the crop early on and in the summer are important to protect yields.”


Similar spending on herbicides across the board suggested that all growers consider getting the crop well established and off to a good start without any weed competition is a key starting point. Likewise, expenditure on molluscicides to rid the crop of slugs around establishment was similar for all.


With soil types there was no obvious pattern, the top and bottom quartiles showing a similar spread of yields according to their land. Most of the crop, 70%, was grown on heavy soils, with just 8% on light land.


Mr Myers concludes that judicious use of inputs and extra care over agronomy detail are likely to give the best returns.


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Attaining the best oilseed rape yield demands care from cultivation and drilling, through the all-important establishment phase and right through to harvest, says BASF’s Will Reyer.”We know that getting the crop off to a good start is paramount, and this means creating a good seed-bed and establishing the crop well.


“It also means creating the right conditions for pre-emergence herbicides, such as Novall, Oryx, Springbok and Shadow, to work.


“Weeds can compete heavily with the emerging crop, and getting your herbicide programme right pays dividends. Just 10 cleavers plants/sq m can cause losses of over £250/ha.”


Diseases can cause significant losses, so control is vital if high yields are to be achieved, adds Mr Reyer.


“Phoma or stem canker can erode rape yields by up to 50% and light leaf spot by up to 40%. A two-spray programme of an effective triazole fungicide, such as Caramba (metconazole), can reduce phoma and prevent cankers being produced in the spring.


“But it is probably sclerotinia that’s the most worrying and damaging disease. The past two years have seen unprecedented levels and this will mean that 2009 is also likely to be a high-pressure year.”


High levels of sclerotia in soil, spores able to travel up to 150m, plus the possibility of another prolonged flowering period, all add up to a high risk year, he believes.


BASF advice is to plan a two-spray programme using fungicides with proven persistence and performance.


In HGCA independent trials,Filan (boscalid) and Compass (thiophanate-methyl + iprodione) gave excellent sclerotinia control when applied at the correct time and at appropriate doses, he notes.


Crops table 3“ADAS advises growers to use minimum three-quarter doses, to consider a two-spray programme and make sure crop coverage is good.”


Unlike triazole fungicides, both Compass and Filan can be tank-mixed with a pyrethroid insecticide for pest control – another area that needs attention if yields are to be maximised, says Mr Reyer.


Seed weevil and pod midge can cause premature pod shatter and losses of up to 0.5t/ha, so their impact on returns can be considerable.


As midges lay their eggs through the egg-laying pod punctures made by weevils, the thresholds and control measures for these pests are linked, he points out.


“A persistent product is needed to make sure the crop is protected against egg-laying and larval invasion throughout the risk period, and the pyrethroid contest (alpha-cypermethrin) has been shown to be more effective and more persistent than other pyrethroids.


“It’s recommended that spraying should be carried out in late evening or early morning or in dull weather, and local beekeepers should be advised of the intention to spray and the chemical being used.”

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