Narrator: In 2018 the fallout of frosts was felt throughout
WA's central and southern production zones, South Australia's mid-north and Mallee, and
southern New South Wales.
Early sown canola and cereals were hit hardest, highlighting the ongoing importance of management
strategies including how to identify signs of frost.
Ben Biddulph: DPIRD researcher Currently the best indication we have is less
than 2 degrees inside a Stevenson's screen, an indication there might have been a frost.
So, quite often when you go into a paddock there's a whole range of symptoms from multiple
different frost events not just one frost event.
At Dale about 100 kilometres east of Perth, the Department of Primary Industries and Regional
Development has established a 20-hectare, long term research site and is co-investing
with the GRDC to look at agronomic options to manage frost risk in historically frost-prone
environments such as this.
We're using around 5 hectares a year for trials, so the results are continually released at
Autumn updates to growers and industry.
Paddock inspections 5 to 7 days after a frost will reveal the extent of any damage but you
must know what you're looking for because symptoms aren't always apparent.
So here you can see we've got healthy plump grains here, which are filling normally, and
those that have been frosted during the recent frost events.
So generally when you go into a paddock where you think there might have been frost damage
you generally have to go through and inspect the different parts of the plant.
Clear stem frost and whole head frost damage is normally really visual and easy to check
because you can see that from miles away.
But if the frost has occurred during stem elongation, so around Z-31 to 37, you can
basically have to go apart and pull apart the leaf sheaves and dissect out to try and
find the actual developing head, to make sure that's OK.
Later on, as we get through to head emergence and early flowering we can quite often see
stem damage there so damage to the actual stem.
Crops, which are frosted during grain development can be quite challenging to assess, particularly
cause when you drive past they will look fine.
You actually have to go through and pull apart the glumes and actually check that the grain's
developing properly, make sure you don't have withered up grains and make sure they're actually
filling and developing properly.
At the moment these should be like watery ripe and a clear juice comes out but 'cos
they're frosted they're just like paper.
Quite often you might not actually know and you might have to tag and then come back a
another week later to check to make sure that they are still developing and growing.
Assessing oats and barley is similar although stem damage isn't as common as in wheat.
Flowering frost damage is a lot easier to see in barley because you don't generally
have to dissect it when you get to mid grain fill, you can see the grains that are lost.
But grain frost damage you basically have to go through and squeeze the grain to make
sure they're developing properly.
Post frost management options include cutting for hay, adjusting harvester settings for
frosted crops, being conscious of greater risk of header fires and testing seed quality
prior to seeding.
Best practice is a frost strategy prior to the season
Most of the frost management actually occurs in our pre-seeding planning in turning planning
actually ah a crop type by sowing date selections for different parts of the landscape, so trying
to basically you know consciously manage those areas we know are more frost prone differently.
So making sure we're managing them according to their frost risk.
Image analysis from drones is being tested to rapidly identify and map the extent of
frost damage and its one part of GRDC's push to help improve frost management overall.
Yes so over the last few years we've had a couple of PhD students at the University of
Western Australia looking at assessing frost damage and developing more rapid frost damage
assessments after a frost.
So trying to bring it from you know when we have to wait 5 to 7 days to see the visual
symptoms of damage, trying to bring that back to you know 2 to 3 days to actually assess
that damage quickly.
An easy-to-use, on-line cereals frost identification guide has been released by D-PIRD with support
from GRDC.
Its basically a step by step guide that growers can use to assess crops for stem elongation
frost damage, whole head frost damage, stem damage, as well as damage to the reproductive
tissue and developing grain.
Ben's advice?
Be alert but not alarmed in establishing and applying management techniques.
Go out and assess your crops, have a look find out where that damage is so you can plan
the impact its likely to have on production for this season so in those really prone areas
you know reconsider what enterprises you're running in that part of the system, your time
of sowing and cultivar choice for that part of the production system.
And in then in your less prone areas continue on as usual and try and maximise your production.