Let's have a more advanced discussion about BYDV sprays
- Thread starter Feldspar
- Start date
Hindsight
Member
- Location
- Lincolnshire
The initial pyrethroid probably provided 7 to 10 days of cover. Thus your crop is effectively not covered since 1 November. Now need to consider whether aphids have reinfested the crop since then. And it will only so far be winged aphids - so you can now use the T170 method to decide when or if another treatment is required - thus allowing you to let the next few weeks weather develop.
Good technical data available on AHDB website - weekly technical notes which you and your agronomist should read and digest for guidance. Read through the weekly documents to provide guidance alongside your agronomist. That's what they are there for.
https://cereals.ahdb.org.uk/monitoring/aphid-news/aphid-news-archive-(2016-2017).aspx
Thanks very much indeed.
yellow belly
Member
- Location
- south west lincolnshire
"Only a small proportion of aphids entering cereals are likely to be carrying BYDV"
the question is how few carry bydv we need some context
in the past I have seen aphid not sprayed and not seen bydv
also not seen aphids and seen some bydv one or 2 small coffee table sized areas in a 10 acre field so I have not sprayed for 25 years and now I am firmly of the opinion that here the preditors do the job or the winter kills or supresses them
the question is how few carry bydv we need some context
in the past I have seen aphid not sprayed and not seen bydv
also not seen aphids and seen some bydv one or 2 small coffee table sized areas in a 10 acre field so I have not sprayed for 25 years and now I am firmly of the opinion that here the preditors do the job or the winter kills or supresses them
- Location
- Essex Coast
Every now and then I go all environmentally friendly and decide to stop using insecticides. This is the last time, 2016.
It was a particularly bad year and some fields only had a few patches, but this one, being the worst, would have lost at least a ton an acre. What was most noticeable was that behind where the picture was taken is a small 3 acre permanent grass field with a 30 feet gap in the hedge between the two. It was quite clear that an Easterly wind blew the aphids through the gap and they fanned out across the wheat.
This tells me that the green bridge thing is a myth and that it only takes one day when the aphids are in the air and the wind is in the right direction to cause a huge amount of damage. I am afraid it also disproves that some how no-till preserves predators or changes the look of the crop so that aphids are not so attracted to it.
The only conclusion I have come to after 9 pages of this thread is that the guys who say they don't see enough BYDV to need spraying are all well inland and on higher ground, and the ones who dare not risk it are in the West Country, along the South Coast, or are at sea level and, like me, surrounded by water. So it seems to me that it just comes down to your local climate and whether you get enough frosty weather to control them. I have looked up data from my local weather station and we only had one frost in the winter of 2015-16 of -2, and that was in February, after most of the damage would have been done.
I have sprayed all my wheat with Hallmark this year because I can't see how to mitigate the risk at the moment and I really do want to grow decent crops.
It was a particularly bad year and some fields only had a few patches, but this one, being the worst, would have lost at least a ton an acre. What was most noticeable was that behind where the picture was taken is a small 3 acre permanent grass field with a 30 feet gap in the hedge between the two. It was quite clear that an Easterly wind blew the aphids through the gap and they fanned out across the wheat.
This tells me that the green bridge thing is a myth and that it only takes one day when the aphids are in the air and the wind is in the right direction to cause a huge amount of damage. I am afraid it also disproves that some how no-till preserves predators or changes the look of the crop so that aphids are not so attracted to it.
The only conclusion I have come to after 9 pages of this thread is that the guys who say they don't see enough BYDV to need spraying are all well inland and on higher ground, and the ones who dare not risk it are in the West Country, along the South Coast, or are at sea level and, like me, surrounded by water. So it seems to me that it just comes down to your local climate and whether you get enough frosty weather to control them. I have looked up data from my local weather station and we only had one frost in the winter of 2015-16 of -2, and that was in February, after most of the damage would have been done.
I have sprayed all my wheat with Hallmark this year because I can't see how to mitigate the risk at the moment and I really do want to grow decent crops.
ollie989898
Member
You need to grow the maximum yield per unit area that you possibly can. THAT is how you minimise your impact on the environment.
Another day of 12 degrees tomorrow and some drizzle. A perfect aphid day.
Another day of 12 degrees tomorrow and some drizzle. A perfect aphid day.
Hindsight
Member
- Location
- Lincolnshire
I was about to post and then did not but having seen SimonC post will now. I think you farm some 100 metres ABSL. I have found aphids easily at sea level and through to the fen edge (15metres ABSL) the last aphids I spotted were last Monday on wheat that was literally just emerged and barely 2 cm tall. In Lincolnshire my view is altitude needs factoring into any decision for autumn aphicide. The temperature differential is key.
Is there an autumn cereal approved insecticide that is more selective in its activity on non aphid species? Mavrik (tau–fluvalinate) is supposed to be less indiscriminate. Pirimicarb has been discussed before but that is not an option at this time of year.
@Woodlander @ollie989898 @richard hammond @david
@Woodlander @ollie989898 @richard hammond @david
Hindsight
Member
- Location
- Lincolnshire
Excellent post. Mirrors what I saw in autumn 2015 where crops not treated in the autumn. Now last autumn was different again but the winter temperatures lower overall although I did spy in late May a few very tiny spots about size of an umbrella in early October sown fields of wheat that did not receive any aphicide or Deter - these fields were at Sea Level near the coast and also low land to east of Stamford. There was a good paper last winter by Alan Dewar but I cannot recall where I put it. Aphid / BYDV is in my view very much local. Those that have not see it having not treated for several years are probably safe. But on lower land I am more wary.
Louis Mc
Member
- Location
- Meath, Ireland
That's bollox....to maximise yield regardless of how you do it is best for the environment?? Come on now....think before you type
ollie989898
Member
Nope. More yield from less land is better for the environment, as less land is required in total.
This view is held by several prominent environmentalists.
Louis Mc
Member
- Location
- Meath, Ireland
A scientist told me so won't dig you out of that I'm afraid.
He does have a point there, but is the intensity of our crop production creating this problem in the first place?
ollie989898
Member
https://eowilsonfoundation.org/e-o-wilson/
- Newcomb Cleveland Prize (1967)
- Leidy Award (1979)
- Pulitzer Prize (1979)
- Tyler Prize for Environmental Achievement (1984)
- Crafoord Prize (1990)
- Pulitzer Prize (1991)
- International Prize for Biology (1993)
- Carl Sagan Award for
Public Understanding of Science (1994) - Kistler Prize (2000)
- Nierenberg Prize (2001)
- BBVA Foundation Frontiers of Knowledge Award in Ecology and Conservation Biology (2010)
- International Cosmos Prize (2012)
https://www.theatlantic.com/magazine/archive/2011/11/e-o-wilsons-theory-of-everything/308686/
.... I flew in by helicopter..... people are really using the poorest methods to eke out a living, and very little technology. ......With the introduction of fertilizers and better irrigation and more machinery, the yields could go up pretty quickly, and so would people’s incomes...... you would see is people moving to cities, and new cities forming, which is the way to relieve pressure on the land..... Africa is the world’s fastest-urbanizing continent.....
Also
....an idea whose logic flows directly from the precepts of island biogeography, which show a dramatic correlation between the size of a habitat and both its diversity and its sustainability.....
High yield agriculture is far far better for the environment. Because more land can be left the hell alone.
shakerator
Member
- Location
- LINCS
Why does it show green bridge is a myth ?
- Location
- Essex Coast
I'm just thinking that you can do all the right things by spraying off early and making sure there is nothing growing when the next crop comes up and then a few thousand aphids blow across one afternoon and you're stuffed.
Green bridge theory assumes that aphids can only walk about, but obviously they can fly and be blown in the wind. What is the point of not having anywhere for aphids to survive in the cropped area if it is surrounded by grass margins and hay paddocks.
shakerator
Member
- Location
- LINCS
I thought it was direct transfer vs standard migration like yours. The key being wingless populations are already established in situ so you lose the luxury of 170 day degrees before significant spread (i.e. You need to spray very soon after emergence or use deter rather than spray sometime now)
Hindsight
Member
- Location
- Lincolnshire
Sorry but another question for you Simon C. Casting your mind back to autumn 2015 did you consider applying a pyrethroid? Just that I am always intrigued by all our decision making process. And the influence of experience. I assume the crop was not Deter treated. I ask as in the autumn of 2015 the 'experts' forecast a high risk especially as November and December was so unseasonably warm and aphids were being caught in the suction traps well into December indicating unusually late flights in that autumn. This was widely published and I think was the subject of a thread on here. Indeed Rothamsted published an exceptional aphid bulletin in early December if I recall flagging up the increased risk.
Regards,
- Location
- Essex Coast
Yes John, I dare say you are right. It is just that I have seen this wind blown infestation several times over the years and it's effects seem to be hundreds of times worse that wingless aphids wandering around in a seedbed.
Trouble is there is so much talk about drilling "on the green" and spraying off after drilling, which people are doing successfully, makes you wonder what is right.