While it will make well-informed variety choice and early agronomy more important than ever, it need have no negative impact on either yields or growing costs. Unless, that is, it leads to knee-jerk reactions such as increased seed rates which could easily do more harm than good.
This was the conclusion of a round table hosted by Dekalb and BASF to explore the reality of an immediate future without the country’s most widely-used OSR seed treatments.
Dekalb seeds and traits manager Deryn Gilbey says: “The loss of neonicotinoids is understandably concerning for growers, but we have to keep things in perspective.
“We were successfully producing OSR for more than 30 years before we had access to this chemistry and with far less vigorous varieties and effective establishment systems than we have today. Also we need to remember a six to eight week period of activity meant they never entirely eliminated the need for autumn insecticide spraying.
“Although about two-thirds of the annual OSR crop is typically affected by the cabbage stem flea beetle and flea beetle pests. We know levels of infestation and crop damage vary very widely from season to season, farm to farm and field to field.”
BASF agronomy manager Clare Tucker is adamant growers should avoid the temptation to increase seed rates in response to the loss of neonicotinoids, pointing out thin-stemmed plants are more vulnerable to damage from flea beetle larvae within their stems than thicker, more robust ones.
With risks both from pyrethroid resistance and to farming’s environmental image, she is also concerned to avoid an upsurge in blanket autumn insecticide spraying, wherever possible, especially so given the great variability of flea beetle and aphid populations.
She says: “More attention to early agronomy must be the main management priority. If we can get crops away well, they are far better placed to withstand flea beetle damage.
“At the same time, they will cope with slug and pigeon problems better too. And they will be better able to tolerate early phoma infections, compete with late weed germination and survive challenging winter conditions.”
Ms Tucker sees two clear elements of agronomic attention as important in this respect – ensuring the right establishment conditions, and early removal of the weeds which can interfere so significantly with crop development and subsequent performance.
“On the spray front, it may well be necessary to integrate extra pyrethroids into the programme to keep on top of any early insect threats. This won’t be either difficult or expensive to include with the early post-em herbicide or later with the graminicide or fungicide.”