We're now going to have a look at field peas, a crop that's growing also grown in southern Australia.
What we tend to find is that of all the winter pulses, peas are the most susceptible to frost damage, particularly during the very productive period.
Where what we see is they don't have any clear signs of vegetative frost, if frost occurs during this window.
So, Jason, if we were looking for frost in field pea during the reproductive period, what would we be looking for?
So while we're standing here in a relatively mature pea crop, it's still pretty easy to identify the key symptoms in peas and on the pods of peas.
And it's probably a really good time to have a look at the frost damage you've got in your pea crop because you can really start estimating the yield losses.
So this pod here just highlights the discolouration across a number of seeds at different points of development.
So you can see that dark brown colouring on the seeds.
And so these seeds will probably still be harvested but will have discoloured seed coats.
So this is a slightly earlier phase pod which had been affected when it was right in the flat pod stage.
You can see the whitish webbing on the outside of the pod.
So they're not that nice green colour.
And then we open it up and you can see the undeveloped or immature seeds on the inside here, which have been severely affected by the frost, gone completely black and won't develop to anything.
So Jason, by comparison, here we have a couple of healthy pea pods.
What you see is a very nice round peas forming there with no clear signs of frost damage.
And that's what we're really wanting to see.
And they're also quite plump.
And the second one here is another pod that is further along and closer to physiological maturity.
What you see is some dimpling, which is natural in field pea seed, but importantly there is no signs of frost damage.
So that's what we're looking for in a healthy pea pod.
So what do you reckon, do you reckon that could be frost in here?
Yeah, well, there's a couple of flowers that have died, which is definitely a sign of frost, amongst other factors.
But yeah, it certainly could be frost there.
The heat events could also get us, couldn't they so yeah?
Yeah, they could.
And just over here, I reckon that's a good example of one where you get one flower aborted and a pod that's actually set.
So, you know, just things to look for.
It is.
I guess it's also important to note that if you wanting to understand what's going on, look at these flowers here and perhaps look back in at your weather radar and see if there's been a frost or heat event.
And that will help you understand what's driven your flower loss.
And if you actually tag those flowers, couldn't you?
Follow them through and see where they set pods?
Yeah, you could.
Which would be really useful in understanding the damage and extent across the paddock.
One way you might be able to keep track of the frost damage in your paddock is to pin particular spatial zones.
So you can either choose to do this in different areas across the paddock where you might have seen different responses in previous years or areas that you've noticed frost that you want to keep an eye on.
So for example, you could put this pin in and if you really want to keep a really close eye on what's happening in the paddock, you can tag key parts, so pods or flowers and track them throughout the season.
This will help inform areas of your paddock that are more prone to frost and how it's affecting your overall harvest.
In summary, when thinking about frost and the risk to field peas, it's important to remember that they are the most susceptible winter pulse to frost, particularly during the reproductive period.
We don't tend to see damage during the vegetative period, which is important to note.
But when moving into that reproductive period, it's really important to keep an eye on what's happening.
So firstly, assessing your flowers for pod for them to drop off or also them to be aborted.
Secondly, you need to be looking at your pods, which are most certainly the most susceptible component of the plant to frost.
So looking for shrivelling of the pod wall or you can also see if you lift them up, they're often transparent.
And then when you open them, you may have small black seeds.
Or secondly, you may also have discolouration and shrivelling of those more mature seeds which are clear indicators of frost damage within that field pea crop.