The much-debated restrictions on neonicotinoid seed treatments will begin this December. The RSPB supports the ban but shares the concern expressed by many that farmers may resort to using greater amounts of other pesticides.
Like farmers across the country we at Hope Farm are reviewing our pest management strategy in light of the ban. We had a head start as RSPB decided in December 2012 to phase out neonicotinoid use on our estate, unless there are exceptional reasons to use them e.g. for research. I thought I’d share our experiences so far.
We haven’t often used neonicotinoids in the past. For our wheat crop it hasn’t made economic or agronomic sense to use treated seeds, and we usually establish our oilseed rape (OSR) by a broadcast method. Since this leaves seeds lying on the surface where birds might find them, use of neonic-treated seeds is prohibited. Instead we spray with pyrethroids (another type of insecticide) to control insect pests as needed.
In the 2012 planting season, conditions were such that we had to use a drilling method to establish some of our OSR. This meant the seeds would be buried and raised the question of whether we should use treated or untreated seeds.
After discussions with our agronomist we ended up with a field of drilled, treated seeds and two fields of broadcast, untreated seeds. This year, we have again decided to drill one of our fields, this time with untreated seeds in line with our new policy.
Oilseed drilling at Hope Farm copyright Andy Hay (RSPB Images)
We didn’t set this up as an experiment but it has enabled us to make some (non-scientific) observations. One surprising fact was that the OSR treated with neonicotinoids needed nearly as many pyrethroid sprays as the broadcast, untreated crop. The untreated crop was sprayed twice in autumn and three times in spring/summer. The treated crop only needed one spray in autumn but still required all three summer sprays.
So in this situation the benefits of seed treatment did not seem very great. On the other hand, this year’s field of drilled, untreated seed is suffering from flea beetle damage and may well end up needing extra pyrethroid sprays.
What do we take from this? That the picture is more complex than a choice between neonicotinoids and sprays. Our experience shows how the outcome of the neonics ban could depend greatly on the crop management choices farmers make. It’s interesting that, nationally, use of pyrethroids hasn’t dropped since neonicotinoids came on the scene - you can check out the figures yourself at https://secure.fera.defra.gov.uk/pusstats/.
RSPB scientists believe that the risks to bees from neonics are greater than those from sprays such as pyrethroids. The priority is to help farmers to use sprays wisely, as part of an Integrated Pest Management strategy – an approach we continue to develop at Hope Farm.
There are still many questions to be answered on neonicotinoids. This is why we are hosting a PhD project at Hope Farm to look at whether wild plants round the edges of a treated wheat field become contaminated with the neonicotinoid (clothianidin). Wheat is not covered by the restrictions because it does not attract pollinating insects.
This is a rapidly developing area of study with real consequences for wildlife and farmers alike. We are pleased to be adding to the growing science on this topic so we can clearly identify the risks to wildlife, but we are equally interested in learning what the real consequences are to the farmer of changes in regulations.
This is one of the cornerstones of Hope Farm, and indeed RSPB farmland research - carrying out studies in challenging subjects and finding realistic solutions to these problems so that farming and wildlife can happily co-exist.
Couldn't have written that better myself!
If you ever want to visit Hope Farm let me know and I'm sure we'll be able to set something up
Thanks for that info. I do my own agronomy here so I am very interested in what sprays other people are using. I generally try to avoid spring/summer insecticides if at all possible but if thresholds are reached then treatment has to be considered. I was expecting to treat for pollen beetle last year due to crops being so backward, but numbers still didn't reach threshold during the green to yellow bud stage. Seed weevil numbers were quite high at flowering and I do think with hindsight I should have sprayed for those.
What Is clear is that neonicotinoid seed treatments have no effect on these spring pests in the winter oilseed rape crop as they will have run out of steam months ago, and your work shows this. Whether they are still present in large enough amounts to do harm to bees feeding at flowering time is another matter, and I hope we can find a definitive answer to this in the next couple of years.
The seed treatments are targeting pests at establishment, mainly flea beetle, so when considering the impact of alternative sprays we have to bear in mind the timing. Autumn sprays are a far lower risk to non target organisms as the crop itself is not flowering. The only bees I have seen in the vicinity of oilseed rape crops this autumn have been in the hedgerows on the ivy. The risk to these bees should be minimal if pesticides are applied correctly with buffer zones adopted where required. The beauty of seed treatments however is you don't have to worry about drift into hedgerows. The seed treatment only lasts about 6 weeks so we have to keep an eye on aphids coming into the crop spreading virus. I have been monitoring suction trap data from HGCA and so far very few aphids have been caught, and i haven't seen any in our crops, so I'm hoping ours will be safe now till the spring. During the next 2 years pest forecasting systems will be very important to determine when we need to spray, as we learn how to live without neonicotinoid seed treatments.
Hi Andy,
We use an independent agronomist who advises us and our contractors on when sprays are required and of course what to spray.
In early April he identified that pollen beetles had reached threshold numbers and we sprayed Alphamex 100 EC on 13th April. Subsequently he also identified that seed weevil and pod midges had reached threshold numbers during the flowering stage. Euro Lambda 100 CS was sprayed on 20th May and Seal Z on 7th June.
There is quite often a compromise between our conservation objectives and the requirements of crop husbandry but we try to limit the spraying of any chemical as far as is reasonably possible.
Interesting findings. What were the target pests in the spring? I rarely need to spray once in the spring, let alone three times.