Feldspar
Member
- Location
- Essex, Cambs and Suffolk
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).
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).