Let's have a more advanced discussion about BYDV sprays

[Feldspar]

One of the areas which I don't feel I've got anywhere near enough information to make good evidence-based decisions on is BYDV spraying in the autumn.

Speaking to agronomists they come out with various approaches like, "It's a philosophy thing: either you do spray for it or you don't." Or they say, "I've seen some terrible BYDV in crops over in the past; it simply isn't worth the risk of not spraying." But most of these views, as far as I can see at least, don't seem to be relying on very much solid trials data that I they can point me to. Instead it's observation, experience and hearsay (a lot of which may well have been built on past work a few decades ago), but what I really want is slightly harder research and data to look at myself.

I want to use this thread to build a collection of what evidence there is out there that provides some numbers to aid decision making. I want to know, for example, what the average yield loss is across all BYDV experiments as well as the range in trials that are as close my situation as possible. Obviously it would be nice to have extensive trials data very close to home on the same altitude, topography, drilling date etc as what we do to make it maximally relevant, but this isn't going to happen. Instead it will be piecing together trials from around the world to act as pieces of a jigsaw to try and improve the picture.

Why do I think this is important? Well it seems to me that there is a largely prophylactic approach to insecticide use in many crops, and this is a good example. There is usually some nod towards noting variations in numbers of aphids caught in traps, but this only seems to affect the insecticide programme in a minor way. When we have the recent study which hit the mainstream press about the decline in insect numbers (http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0185809), I think we need to bring in wider impacts into our cost-benefit analyses.

To start the ball rolling, take this French study which looks at yield effects from BYDV: https://apsjournals.apsnet.org/doi/abs/10.1094/PHYTO.2003.93.10.1217. They develop a model which gives a reactive trigger for treatment that lowers the costs of dealing with BYDV over a prophylactic approach. That's lower cost to the farmer and takes no account of wider landscape effects. Their economic threshold for the yield loss that equals the treatment costs is 0.5 t/ha. Different country, different climate, different varieties and more, so not extremely representative, but it's also not totally irrelevant.

Some key points I took from it.... (tbc when I have a bit more time).

 

[ollie989898]

You mess with BYDV with your peril. It can be nasty. If you don't want to spray that would be AOK with me, save yourself a sliver of cash and protect the bugs, it would also save me having to do a rec and sending product. Don't complain you have BYDV in May though.

It really isn't worth messing with, and if you wanted to save the bugs and birds you wouldn't be involved in field scale monoculture or even arable farming anyway.

 

[beefandsleep]

I had a discussion with my agronomist today. I asked him if I really needed to spray an autumn insecticide on my winter barley as I really didn’t want to unless necessary. He said unquestionably yes. At around £3 /ha when I’m going through with herbicide anyway it is cheap arse covering really, how can the economic threshold be 0.5t/ha?

 

[shakerator]

One of the areas which I don't feel I've got anywhere near enough information to make good evidence-based decisions on is BYDV spraying in the autumn.

Speaking to agronomists they come out with various approaches like, "It's a philosophy thing: either you do spray for it or you don't." Or they say, "I've seen some terrible BYDV in crops over in the past; it simply isn't worth the risk of not spraying." But most of these views, as far as I can see at least, don't seem to be relying on very much solid trials data that I they can point me to. Instead it's observation, experience and hearsay (a lot of which may well have been built on past work a few decades ago), but what I really want is slightly harder research and data to look at myself.

I want to use this thread to build a collection of what evidence there is out there that provides some numbers to aid decision making. I want to know, for example, what the average yield loss is across all BYDV experiments as well as the range in trials that are as close my situation as possible. Obviously it would be nice to have extensive trials data very close to home on the same altitude, topography, drilling date etc as what we do to make it maximally relevant, but this isn't going to happen. Instead it will be piecing together trials from around the world to act as pieces of a jigsaw to try and improve the picture.

Why do I think this is important? Well it seems to me that there is a largely prophylactic approach to insecticide use in many crops, and this is a good example. There is usually some nod towards noting variations in numbers of aphids caught in traps, but this only seems to affect the insecticide programme in a minor way. When we have the recent study which hit the mainstream press about the decline in insect numbers (http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0185809), I think we need to bring in wider impacts into our cost-benefit analyses.

To start the ball rolling, take this French study which looks at yield effects from BYDV: https://apsjournals.apsnet.org/doi/abs/10.1094/PHYTO.2003.93.10.1217. They develop a model which gives a reactive trigger for treatment that lowers the costs of dealing with BYDV over a prophylactic approach. That's lower cost to the farmer and takes no account of wider landscape effects. Their economic threshold for the yield loss that equals the treatment costs is 0.5 t/ha. Different country, different climate, different varieties and more, so not extremely representative, but it's also not totally irrelevant.

Some key points I took from it.... (tbc when I have a bit more time).

It's a dangerous discussion....... I've done it to death. And I still spray

 

[Fish]

As my farm surrounds an RAF airfield, on which there is 6-700 ha of grass, and if the wheat crops are at GS 12+ on the first of November then I will spray.
This year we had bad BYVD in no till spring wheat after grass.

 

[Gong Farmer]

What sort of yield loss do you think came from this? (and it wasn't an untreated plot)

 

[Breckland Boy]

I looked at my barley yesterday.
It was full of aphids.
I sprayed them this morning.
No redigo deter dressing on the seed meant it was a no brained.
Two years ago I got caught out and the patches of BYDV covered pretty much whole fields.
The potential losses are far greater than the cost of an insecticide.

 

[yellow belly]

the risk depends when the crop emerged and the winter weather afterwards

if I had mid September emerged crops with full cultivations the preditor base is less so spraying is a must if the crop has many aphids

but mid October emerged crops with notill and many preditors followed by a winter with a cold week the risk is nill this far east and north

on Friday while spreading avadex the numbers of ladybirds was high also the levels of spiders webs covered every inch of fields notill with osr cover

aphids are easy to find
in the 1990s I sprayed on finding aphids left a field there was no difference so have not sprayed since

the work then showed that spraying in march was adequate if the winter had not killed them

further west and earlier drilled is a different situation those areas get much warmer weather and do not have the aphid killing cold easterly winds we get

 

[Against_the_grain]

The cost of the chemical means that its very cheap insurance against huge yield loss. In other words its worth paying the insurance premium in this instance much like it is with most/all of our chemical applications. All we are doing is protecting the yield. We as the farmers have to decide how much we want to protect our investment and how much we want to risk based on evidence from AHDB etc/atittude to risk and financial constraints.....it really is that simple imo

 

[Flat 10]

About the only insecticide I regularly use now is BYDV. Risks are massive and I doubt I am hurting much else at that time of year (though I'm probably wrong). Have nightmares about them banning neonics on beet and spraying that for virus yellows...........

 

[yellow belly]

The cost of the chemical means that its very cheap insurance against huge yield loss. In other words its worth paying the insurance premium in this instance much like it is with most/all of our chemical applications. All we are doing is protecting the yield. We as the farmers have to decide how much we want to protect our investment and how much we want to risk based on evidence from AHDB etc/atittude to risk and financial constraints.....it really is that simple imo

you could wait till march if the winter is hard enough and the aphids all disappear /die and not harm the beneficials which then build up to control the problem

the picture on the left is black bean aphid controlled by lady bird lavae when we inspected the crop there were 1% of plants with aphid 2 weeks later there were non affected these field are now winter wheat with lady birds active as of last Monday

 

[ZXR17]

View attachment 596272

What sort of yield loss do you think came from this? (and it wasn't an untreated plot)

Do tell us then. Looking at that plot I would say about 65%.
I had acres almost as bad as that a couple of years ago , it was worse in the wheat than the barley.

 

[Hindsight]

Do tell us then. Looking at that plot I would say about 65%.
I had acres almost as bad as that a couple of years ago , it was worse in the wheat than the barley.

And what treatment, if any did you apply in the autumn 2015, and sowing date of the cereals. I too was caught with BYDV in spring 2016 following the very warm autumn 2015, prolonged aphid activity and lack of any frost periods to cease aphid activity.

 

[ollie989898]

I'm sure in spring 2016 that even the spring barley was getting BYDV!

 

[Against_the_grain]

you could wait till march if the winter is hard enough and the aphids all disappear /die and not harm the beneficials which then build up to control the problem

the picture on the left is black bean aphid controlled by lady bird lavae when we inspected the crop there were 1% of plants with aphid 2 weeks later there were non affected these field are now winter wheat with lady birds active as of last Monday

I agree that beneficals can play a role and we see this in beans with bruchid beetle but I am not prepared to risk £130/ha + for the sake of £5/ha or whatever the cost of an insecticide is when it comes to bydv

 

[ollie989898]

Seriously now, you won't convince me with your green credentials, not after you have sprayed off/cultivated/drilled and planted a monoculture. That's not a wildlife habitat in anyone's book. If you are serious about reducing your impact on the environment you need to be taking land out of cultivation, sowing it with native grasses and leaving it be. I'm talking margins of 12-20 metres, leaving it alone or even planting trees back there.

Opting not to use an insecticide on the basis that you don't want to harm the environment is like saying you did the weekly run to Tesco at 50mph instead of 60mph out of the goodness of your heart. You realise that a lot of the fungicides and PGRs have arthropod exclusion zones on the can because they give spiders more than a bad hair day?

 

[Feldspar]

Seriously now, you won't convince me with your green credentials, not after you have sprayed off/cultivated/drilled and planted a monoculture. That's not a wildlife habitat in anyone's book. If you are serious about reducing your impact on the environment you need to be taking land out of cultivation, sowing it with native grasses and leaving it be. I'm talking margins of 12-20 metres, leaving it alone or even planting trees back there.

Opting not to use an insecticide on the basis that you don't want to harm the environment is like saying you did the weekly run to Tesco at 50mph instead of 60mph out of the goodness of your heart. You realise that a lot of the fungicides and PGRs have arthropod exclusion zones on the can because they give spiders more than a bad hair day?

I totally disagree with this. We have 200ac out of production in buffers (up to 36m by the way), untouched stubbles, native grass and wildflower meadows and so on. If you think that an arable field is not a wildlife habitat then you clearly haven't been paying much attention. I would go so far as to say that it's a typical chemical agronomist's take on things. Everything is a matter of degrees. Eschewing measures simply because they only do some good is devoid of all logic.

How about contributing seriously to the thread by telling us what evidence / trials work you use when making decisions about BYDV.

 

[ollie989898]

I totally disagree with this. We have 200ac out of production in buffers (up to 36m by the way), untouched stubbles, native grass and wildflower meadows and so on. If you think that an arable field is not a wildlife habitat then you clearly haven't been paying much attention. I would go so far as to say that it's a typical chemical agronomist's take on things. Everything is a matter of degrees. Eschewing measures simply because they only do some good is devoid of all logic.

How about contributing seriously to the thread by telling us what evidence / trials work you use when making decisions about BYDV.

An arable field is not a wildlife habitat. I am describing the bit of land you are putting into production, not the margins or the hedges or other areas you are not putting into cultivation. You might count what, 5 or a dozen even species of plants, a dozen species of birds. These are all vastly less than the number of species found in any areas untouched by the hand of man. That's the whole point of monoculture, establishing one dominant organism because it's output is being directed toward the needs of man.

I am sorry that you do not agree but I don't want people to kid themselves, whether you are growing wheat, maize, beet, spuds or grazing cows on it, you are artificially subverting natures will and putting it to other ends.

Having grassland margins, wildflower meadows and the rest of it is all well and good, but we need to go some way to offset the fact we are monumentally curtailing nature over thousands of square hectares of land as we attempt to grow monoculture.

I don't make any distinction between a field of grass or one of wheat.

And as I have stated, a LOT of new actives have warnings for aquatic life and other issues regarding their use, leaving out 100ml of pyrethroid is not going to make a whole lot of difference where these products are being used anyway.

Regarding the decision making process whether to use anything to control BYDV vectors, you can take advantage of the AHDB aphid monitoring service, unfortunately there is a huge gulf in their coverage in my area. Personally I would go with the weather conditions in the weeks leading up to the timing, but there will always be years where conditions give you a nasty fright.

 

[Feldspar]

An arable field is not a wildlife habitat. I am describing the bit of land you are putting into production, not the margins or the hedges or other areas you are not putting into cultivation. You might count what, 5 or a dozen even species of plants, a dozen species of birds. These are all vastly less than the number of species found in any areas untouched by the hand of man. That's the whole point of monoculture, establishing one dominant organism because it's output is being directed toward the needs of man.

I am sorry that you do not agree but I don't want people to kid themselves, whether you are growing wheat, maize, beet, spuds or grazing cows on it, you are artificially subverting natures will and putting it to other ends.

Having grassland margins, wildflower meadows and the rest of it is all well and good, but we need to go some way to offset the fact we are monumentally curtailing nature over thousands of square hectares of land as we attempt to grow monoculture.

I don't make any distinction between a field of grass or one of wheat.

And as I have stated, a LOT of new actives have warnings for aquatic life and other issues regarding their use, leaving out 100ml of pyrethroid is not going to make a whole lot of difference where these products are being used anyway.

When you talk of species diversity in fields you are forgetting about nearly all the life that is smaller than your thumb. The diversity within this category is more than I think you would imagine. I seriously recommend you spend a bit more time understanding soil biology.

I restate my question about what evidence you're basing your views on.

 

[ollie989898]

When you talk of species diversity in fields you are forgetting about nearly all the life that is smaller than your thumb. The diversity within this category is more than I think you would imagine. I seriously recommend you spend a bit more time understanding soil biology.

I restate my question about what evidence you're basing your views on.

You have already hugely scuppered the soil biology by tilling the dirt, applying nutrients and growing crops in monoculture.

What evidence do you want? You won't find a more ardent environmentalist than me.

Compare this:

With this:

Do you see what I am getting at?