Serious last autumn’s flea beetle challenge may have been for some, but the vast majority of winter oilseed rape crops have gone into the winter in remarkably good shape reveals the DEKALB national OSR establishment survey undertaken by Monsanto over the past month.
Involving telephone interviews with 150 farmers across the country growing almost
13,000 ha of OSR, the independently-run survey shows only just over one in 10 were unhappy with their crop establishment this season. And this despite the sample being deliberately weighted towards areas known to have suffered the highest insect pest pressures.
While a significant amount of re-sowing was necessary in Essex, in particular, and many crops in the worst affected parts of East Anglia and Bedfordshire received three or more insecticide sprays, even in these areas over 70% of growers did not have to re-sow more than a quarter of their crops
“Apart from the areas suffering acutely from flea beetle, most UK growers are very relieved their worst establishment fears haven’t been realised,” noted DEKALB survey co-ordinator, Deryn Gilbey. “Especially so, with the dry September restricting initial growth in many cases and serious slug pressures reported with the wet weather from October.
“Clearly the positive steps taken by many to improve establishment this season by selecting vigorous fast-developing varieties, putting more care and attention into seedbed quality and sowing consistency and extra insecticide spraying, amongst other measures, have paid dividends in combatting both flea beetle and slug threats
Of the 228 crops of 55 different varieties being grown by the survey respondents 58% are hybrids, of which notably vigorous and fast-developing, DK Extrovert, DK Expower,
DK Excellium and Excalibur comprise just under 40%.
“This is just as well as our national results show less than 10% of crops of the five most popular hybrids required any re-sowing against nearly 20% of the five most widely-grown pure lines,” Deryn Gilbey noted. “What’s more, this performance gap was equally obvious among growers reporting high or very high flea beetle pressures.”
As well as the importance of variety choice, the survey’s re-sowing data from those worst affected by flea beetle provide some interesting indications of the value of other key measures taken to improve establishment last autumn.
Only 14% of crops known to have received Mesurol seed treatment, for example, needed some re-sowing compared to 26% of those not treated at all.
Equally, no re-sowing whatsoever was required with crops established in plough-based systems, against between 30% and 40% under other regimes. And some re-sowing proved necessary in 20% of crops experiencing fair soil conditions after sowing in contrast to around 30-40% of those experiencing either dry or wet conditions.
Perhaps most intriguing, though, in view of the early sowing determination on the part of many was the fact that crops sown later in main sowing window needed markedly less re-sowing than those planted earlier
“What these results show more than anything else is the need to prioritise seedbed condition over calendar date in sowing timing,” Deryn Gilbey stressed. “With such unsettled weather in August, getting the crop in well proved far more important than getting it in early in the face of serious flea beetle pressure.
“Our first modern season’s experience without neonicotinoid seed dressings underlines that vigorous varieties sown into the best possible seedbeds are one of our best current defences we have against flea beetle. “The limited protection Mesurol treatment offers has been valuable too, as has repeated insecticide spraying wherever necessary.
“While the establishment period was far from stress-free for many growers and their agronomists in the worst affected parts of the country, all the evidence is that most have been able to cope reasonably well.
“This is very encouraging in the face of increasing pressures on agrochemical development and availability, emphasising the importance of more effective and integrated plant breeding and crop management to the future of oilseed rape growing.”