Transcript

MEADOW GRASS! · Cereal Killers

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Music.
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Hi and welcome back to serial killers the podcast all about
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the pest diseases diseases and weeds of arable
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crops hi josie hello so what's
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today's subject annual meadow grass and rough meadow grass also known as poa
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annua and poa trivialis yeah so we've covered a lot of very bad pernicious weeds
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and diseases over the weeks on serial killers but this one's probably Probably
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not a massive issue for arable crops, really.
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No. It's more of an annoyance, but it does have some interest in biology and
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some interesting times that it crops up in fields.
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So I thought it would be a good one to discuss.
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So Poa annua. Poa is the type genus for all grasses.
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So you'll see that the grass family is named the Poaceae. And then Poa annua,
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meaning that it's an annual plant.
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Or short-lived perennial. yeah so a lot
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of these scientific names are given and then
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they realize that they're not actually correct but they don't
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change them very often no so there's a beetle named
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after hitler and it's still named after hitler but they haven't because
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it's not a scientific reason for changing it it's still there so power
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annua is still called annua even though it's
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short-lived perennial another good one is spider plants
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yeah it's called chlorophyllum or something
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like that meaning and green-leaved and wow a
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plant that's green-leaved that's a really good description and also it's
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not green-leaved it's got yellow white bits and yellow bits in it so
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stupidly named plants poa annua is one of them and so it's a it's a short-lived
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perennial so it means it's not necessarily going to die off in one year but
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it can do if it's stressed so a good example of that is on on golf courses in
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new zealand poa annua gets stressed in the summer and because.
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It dominates it creeps into golf greens and then it just dies off
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in the summer you'll often see like new zealand golfers
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where they just all the greens just dead and that's a traumatic
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experience for them and that name
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is a little bit false as well as in it's more
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of an ephemeral yep rather than
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an annual so an ephemeral plant is a plant
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that will germinate grow away set
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seeds seeds and die within about six
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weeks so it can do six weeks or it can do two years so
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yeah what's that about yeah and also ephemerals
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often don't have mycorrhizal connections so they just rely on on their own ability
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to absorb nutrients from the soil especially bear and so to do that they need
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a lot of free nutrition in the soil and so that's why you'll find poet annua
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on bear land and that's That's where it creeps into farmland.
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When soil has been left for a bear or has been ploughed, that's when Pohran
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will get in. It's not a weed that's going to compete with,
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It will die off and flower and seed before it becomes an issue.
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And the seeds become viable literally after one or two days following pollination.
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So it's right out there.
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Yeah. And even though it dies off, it can still propagate by a rhizome.
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So it's not just seeds. So it's quite a clever plant that can use both.
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The most abundant seed found in soil on footwear.
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So if you're traipsing around, your footwear will pick up all these seeds and spread them.
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I had a professor at university when I was doing my undergraduate at Durham,
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and her job was to analyse the seeds on people's clothes and pollen on people's
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clothes when they've committed a crime and see where they could link them to where a body was found.
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Major interest in. Yeah, or where a safe. So they pack pollen into safes,
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and when you drill a safe, all this pollen is on your clothes. You don't realise it.
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Oh, my goodness. So you just link it back to what the pollen was in the safe.
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Sounds like a fantastic idea for a Netflix movie.
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Movie it does doesn't that yeah yeah or just a uh or a thursday murder club book but there you go.
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So it's not we said it's not going to power annual is not going to annual metagraphs
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is not going to affect your yield it's going to be a pain in certain situations
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it might it might interfere with drilling no you're looking at roughly a reduction
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in yields of about six percent if left unchecked yeah and it's going to be affecting
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across the whole of the uk
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and ireland so it's everywhere but one
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of the bad things about this is that it
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can act as a host for ergot yeah claviceps purpurea
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and we don't like ergot we do not like ergot ergot is
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not good for you and i think the limits for it are getting
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lower as well so something to look after and then the other species of meadow
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grass we were going to talk about was rough meadow grass is that correct poet
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trivialis and is it trivial well it's a perennial plant so it's not that trivial
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yeah and it creeps around so that's not good either.
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And it has good drought and shade tolerance, but it likes damp and shady too.
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Yeah. It likes compacted, damp soils.
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So if you're doing no-till, min-till, and you've got compacted soils and you're
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not dealing with that by other methods, then this could creep in, rough meadow grass.
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But it's fairly easy to control if you plough. I think the stolons are easy
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to break up and things like that.
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So rough meadow grass the seeds need
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vernalization so that's exposure to cold
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temperatures in the winter to flower the following year
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so yeah and you don't get flowers in spring cereals
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so that sort of breaks the cycle so rotation's great
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so yeah and then the other species of power that we think is a of a good species
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is power pretensis and this is found in turf and matthew who edits our podcast
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i put that in just to annoy him because it's got loads of peas in it and he
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popping peas of power pretenses he has to edit those all out you see.
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Smooth meadow grass okay anything else on
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the meadow grasses we should the rough meadow grass has started to develop a
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resistance to some herbicides so glyphosate yeah that's kind of an issue there
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because the resistance is growing yeah but you can apply herbicides either before
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Before your seeds emerge or after they've emerged.
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Yeah, and I think you can get fairly good control, so it's not too bad. It's not like it's...
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The other control methods overcompensate for that lack of control from anywhere there is resistance.
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But it's something we need to look at. It could be one for the future. Yeah.
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Well, like anything, they compete for nitrogen with the other plants that are
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in the ground, don't they? Free nitrogen, yeah. Cool. Right.
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And then I suppose if you've got a mycorrhizal crop, crop it'll soon a
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crop that's got mycorrhizal connections it'll soon out compete
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power anywhere brilliant grasses are
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really a little bit boring aren't they yeah so what should we do next then next
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subject what we've got flea beetle flea bees no let's do chocolate spot next
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oh okay yeah i am a little bit hungry yeah there we go get the chocolate out
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and it'll be chocolate spot next week all right thank you very much do see thank you.