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BARLEY YELLOW DWARF VIRUS! · Cereal Killers

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  Music.
• 0:17
  Hi welcome back to serial killers the podcast
• 0:20
  all about the pest diseases weeds and challenges of arable
• 0:23
  crops i've actually already recorded this podcast
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  once but i bored myself senseless and
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  if i was boring myself then i would definitely be boring you so i'm
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  going to do this one and hopefully put a bit more interest and
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  fun into this topic which is bydv i'm
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  going to make the barley yellow dwarf virus as
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  entertaining as i can get so it's awesome
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  and this time of year farmers would be
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  trying to control bydv virus on
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  their on their crops their winter wheat crops
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  that they've recently established however it's been so
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  wet out there that there's no one
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  has drilled or sown their their crops and so there's no
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  need to control bydv yet so this
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  is a timely podcast where you could if you're sat around doing
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  nothing then you can get ahead of the
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  curve and look at potentially novel ways of controlling this
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  very very serious disease
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  of cereal crops and it's such.
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  A serious disease that you can lose up to 60 percent of
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  your yield in winter wheat or 50 percent in
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  winter barley if you don't control it and that's massive and the reason why
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  you get such control such bad losses is because there is no cure for bydv once
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  it's in your plants plants don't have an immune system so unlike covid which
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  i'm currently suffering from.
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  My immune system will fight off COVID eventually. However, a plant can never
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  fight off BYDV because it doesn't have an immune system.
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  Also, there are no viricides available for plants, for any crop.
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  They're not even something that's on the horizon that could potentially be there soon.
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  The closest thing we've got to a cure for viruses is either,
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  it's sort of like RNAi technology,
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  and that's very pretty far off
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  so certainly in cereal crops and then
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  it's questionable whether it would actually be effective in the field so you
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  can't control it the plant hasn't got an immune system to
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  fight it off and so once it's there your losses
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  are tremendous because the virus is sucking the
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  energy out of the plant getting it to produce more virus particles
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  rather than actually producing yield
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  and unusually for a virus it can actually kill
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  the plant as well so normally viruses really harm
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  the plant but actually leave it in a state of
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  sort of stress and ill health rather than actually killing
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  it whereas this one if you get the virus in young
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  plants the young plants will actually die and and
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  as the name suggests it produces yellowing or chlorosis we don't like a scientist
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  we don't like to say yellowing because it's not yellowing because yellowing
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  implies something that's gone yellow whereas actually when plants are chlorotic
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  they've lost their greenness so you would you a better way is to say chlorotic.
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  But yellowing is the name of this one dwarfism is
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  another symptom and then you get red tipping of
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  the leaves in older plants as well it is that's
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  another symptom but that can be compute confused with
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  things like phosphorus deficiency where you get purpling of the
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  leaves and other other things so just like a gp looking
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  at symptoms you need to sort of have a holistic approach to
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  and look at the context to see whether whether whether.
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  That though that yellowing or red tipping or dwarfism is
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  down to a virus you'll get
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  patchiness patchiness is in your crop
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  is symptomatic of of bydv
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  and that's because the virus is transmitted
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  via aphids and so when one aphid lands you
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  get hot spots in the crop rather than just the
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  whole crop or just one plant eventually the
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  whole crop will be will succumb to it if it's
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  not controlled so everything around bydv
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  centers on aphid control because the
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  aphids are what's causing to infection one aphid can
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  infect more than one plant and they propagate
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  on the infected plants and then more more aphids
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  are produced so you need to control the aphids and then
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  the most obvious way of controlling that is with a insecticide
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  and with pyrethroid based insecticide and
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  that that goes on in autumn after establishments
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  and that's why this is a we're doing this podcast now
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  because this is the time when most people are thinking about this this
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  virus okay so there are a couple of aphids that are the major causes of of bydv
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  or the major vectors as we would say in science the first being the south cherry
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  oak aphid and the second being the north grain aphid.
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  And unless you're an aphid expert like Tom Pope, my friend Tom Pope,
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  there's no real reason to know those different species.
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  The way you treat aphid,
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  the disease is not going to be affected by which aphid is attacking it.
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  Okay, so control the aphid, control the virus. There are other ways of controlling
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  the virus or helping control the virus.
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  The aphids will be coming in from field margins, but they'll also be coming in from green bridges.
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  So that could be a weed or a volunteer cereal plant in the field.
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  And then the aphids will, once the previous crop has been harvested.
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  The aphids will have been shook off the plant and will be in the soil.
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  And they won't die immediately and so if
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  you sow your seeds too quickly
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  then that can provide a green bridge as well so leaving
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  five weeks between cultivation and sowing is is recommended and in this year
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  that's not going to be an issue at all because of the soil has been so wet the
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  weather's been so wet so annual meadow grass is as we said in a previous podcast it's not a major.
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  Weed it's not going to it's not going to reduce your
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  yields but it will be a source of
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  infection for for this to destroy annual
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  medagrass and volunteer cereals late drilling
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  mintil also is thought
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  to reduce infection and then it's one of these things where direct
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  drilling will be beneficial and that's
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  because when you're direct drilling you're going to have a much higher
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  beetle and spider and other natural biocontrol
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  agents in in the in the soil in the environment
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  and they will eat the aphids as they go so anything
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  you can do to encourage natural predators of the
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  aphids is going to be good and then
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  also you can get bydv tolerant
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  varieties so especially in recent years a
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  number of varieties have come to the market and these are on the ahdb
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  recommended list as kws ferris
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  for winter barley and rgt wolverine for winter wheat there may be others that
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  since i looked at this that have been released or variants on this and that
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  that's always a good opportunity to exploit if they suit your conditions and
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  the hdb as well as recommended lists they provide.
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  Fortnightly updates on aphid and and
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  thus the risk of bydv in the summer
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  and then weekly updates in the autumn so you could see
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  where where that takes you and
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  what your risk factors are Syngenta as
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  well as providing you know the the insecticides for for this and other companies
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  provide insecticides they also have an app that you can that puts in you know
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  your your location data the the weather data and data from traps and.
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  That you can sort of forecast your risk of BYDV.
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  When you look into the science behind the virus a bit more, it gets very complicated very quickly.
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  So there are a number of different variants, not varieties, and isolates of this virus.
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  Some affect all cereals. Others are distinct to one particular crop type, like oats.
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  And so it's not a case of just one particular virus.
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  There are a number of different variants out there however the
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  control method for them all is pretty much the same there's
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  also the serial yellow dwarf virus and
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  that sounds very similar and it affects
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  the same crops and it's transmitted
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  by some of the same aphids and it's got similar symptoms
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  and it's related but it's still a distinct virus and
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  so the science behind viruses gets really complicated
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  very quickly i think but the good news is
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  you don't actually need to know a great deal about it to
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  get good control so there you go the reason
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  why bydv is top
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  of mind for me is at the moment is because our blackgrass
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  spores our pathogenic spores for blackgrass we're
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  actually putting an extra spray of them on this autumn because we were at the
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  agravista ag-ex event and i'm speaking to a lot of the farmers and the agronomists
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  there and they were saying that this would be a really good time to apply the
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  spores because they could go on with the insecticide because there'd be no compatibility issues.
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  And also, at that time of year, there were no fungicides going on the crop.
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  And obviously, we struggled in the spring with our pathogenic spores because
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  it was so wet that everything was delayed and everything had to go on very close together.
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  And so we were putting fungi on at the same time as a fungicide.
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  And so that sort of limited its effectiveness.
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  So now we're going to go on with another batch of spores on all the farms that
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  signed up for our on-farm trials.
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  And we're going to put them
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  on with the insecticidal spray and so hopefully that could
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  yield really good results because there's not going to be a fungicide there the
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  other thing is that potentially it will weaken the black
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  grass plants during the winter and so
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  they could potentially die off and be
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  out competed by the the cereals come the spring there
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  is also a potential downside of it in that the plants could
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  become sort of immune to to the to
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  the black grass pathogens the black grass plants could.
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  Become immune to it so that's why we're doing the trials because we
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  don't know which one the positive effect or the negative effect is
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  going to be seen in the real world sort of
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  situation so we're really excited about
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  that if anyone listening has has been following
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  the black grass pathogenic spore project that as
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  of today that's now open for more farms
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  to get on board and start trials we've really
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  ramped up production in the lab and we've every.
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  Week we find a new way of producing more and more spores so
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  we're going to go on with more and more spores next year and hopefully.
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  Introduce some more black grass specific
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  pathogens as well so it's a really exciting time on
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  that front as well and which is good news because black
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  grass is not going anywhere anytime soon and then
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  the last point about bydv is that
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  there's there's a real symbiosis between the
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  the plant and the the virus and the aphid
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  in that when the plant's
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  weakened that helps the the
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  aphid in its its ability to suck sap out
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  the plant and vice versa so the you
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  know scientists believe that the sort of symbiosis and they've evolved together
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  and they actually encourage the aphid encourages the virus to
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  be in the plant because a weakened plant suits both parties so
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  there's that symbiosis as well if you've got any other interesting
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  facts about bydv then please get
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  in touch it's not the sort of thing that we can take pictures of
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  easily because you're really only taking pictures of the
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  symptoms you need an electron microscope to to
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  study to study viruses and even then you get a
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  pretty rubbish picture because they're so small but yeah
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  that was bydv not the most interesting of subjects i'll admit but a very timely
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  what subject to cover and i don't know what we're going to cover next probably
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  something on our list go for a probably an insect or a fungus side fungus next okay thank you very much.