ISSUE 2 Better Frost Decisions

ISSUE 2 | OCTOBER/ NOVEMBER 2021

BETTER FROST DECISIONS Knowledge to inform grower and adviser decisions for pre-season planning, in-season management and post-frost event responses

IN THIS ISSUE Temperature mapping frost in the landscape GRDC FrostSense project Regional frost update Mid North Frost Learning Centre Photo K Porker

Where should you place a thermometer to measure frost in the paddock?

It matters a lot where you put a thermometer to measure minimum temperature on a cold clear still night.

During spring, grain growers are keenly watching the three interacting risks of frost, heat and rainfall. Rainfall along with maximum and minimum temperature are the most standard measurements.

Measuring maximum temperature is relatively straightforward providing the data logger is shielded from the sun. Spring heat spikes in the grains belt come with a hot dry northerly wind as there isn’t enough local solar radiation to generate the heat.

Because of the wind and mixing of the air, it doesn’t matter much where in the landscape you place a thermometer or data logger.

Rainfall varies from region to region and farm to farm, but frontal rain in spring is less variable than a summer thunderstorm and rainfall is much less spatially variable across a farm and a paddock than minimum temperature.

Minimum temperature is recognised as the most spatially sensitive parameter and this is especially the case with radiation frosts.

Continued...

WELCOME In the first issue we addressed frost variation in time; some years are frostier than others and some decades seem to be frostier than other decades.

In this issue we address the spatial variability of frost; some regions are frostier than others and some paddocks and parts of the paddock are frostier than others.

We also go around the regions to check in on frost demos and events including the Mid North Frost Learning Centre.

Our regular contributors are Peter Hayman and the team from SARDI Climate Applications and farming systems groups AIR EP, UNFS, MSF, BCG and SFS. Next issue out in December.

Grain growers in the northern hemisphere experience freezing temperature and strong winds in what is called a freeze or in extreme cases, an ice storm. The wind causes mixing and it doesn’t matter where you place the thermometer.

A radiation frost on a clear, calm night where heat is being lost from the wheat paddock to outer space is a special case where temperature can vary over very small distances.

MacroClimate MesoClimate and MicroClimate The terms macro, meso and micro refer to decreasing levels of scale but there is no single definition of the dimension. It is obvious that climate varies at a finer scale than we measure it.

On a frosty night, the ‘microclimate’ in a Stevenson screen 1.2 metres above the ground is different to the microclimate within the paddock.

Read more here When selecting sites for viticulture it is common to refer to climate or macroclimate (the region), mesoclimate (the vineyard) and the microclimate (the vine).

The following table refers to these different levels and includes a fourth level of phyllo-climate or the plant level.

Photos K Porker

Photo Kenton Porker

Researchers and farmers dealing with frost will sometimes say that the BoM site is irrelevant to what happens in the paddock. The BoM site is different to a measure at head height.

If a BoM site was in the coldest frostiest hollow, we are measuring both climate (minimum temperature due to high pressure system and dry cold air) and landscape (cold air drainage).

A measure at head height is a measure of the climate, the landscape and the vigour of the wheat crop.

MacroClimate for the different regions The maps of minimum temperature from the Bureau of Meteorology show the broad scale of frost.

The synoptic chart indicates the slow moving high pressure system covering the extensive region.

Using a selection of Mid and Upper North sites with recent temperature observations, the graphs below show the daily minimum temperatures from July to November over the last 3 years. Overall, the pattern of daily maximum and minimum temperature is similar across the stations.

Daily minimum temperatures during 2019 (top left), 2020 (bottom left) and 2021 until 15th September (above) recorded at Snowtown, Edinburgh, Yongala, Clare, Roseworthy, Nuriootpa and Eudunda in the Mid and Upper North, SA.

MesoClimate

GRDC has an investment with Dr Nidumolu and his team for a project called FrostSense that builds on the minimum temperature monitoring.

The term meso climate is familiar to many growers in the Mid North and Mallee Mesonet.

The Mid North Mesonet is a great resource of very high-quality local data. The system has been co-designed by meteorologists and agriculturalists to measure inversions for spray weather. There are other networks of weather stations such as Data Farmer in the Victorian Mallee and weather stations linked to the soil probe networks.

The goal is to develop an integrated modelling framework to rapidly map the extent of stem and reproductive frost damage in wheat and barley.

30m x 30m mesoscale A project led by Dr Uday Nidumolu from CSIRO based at the Waite Campus, developed a model to combine local terrain data with a single logger to generate 30m x 30m resolution maps of minimum temperature across any paddock in the cereal belt. Read more here When tested on additional paddocks they found between 83% and 96% of the pixels correctly identified above or below the 2 degree threshold.

Read more here

Can you help the FrostSense project with yield maps?

As part of the FrostSense Project, CSIRO is seeking historical yield maps of paddocks so we can use them to analyse the remote sensing data for damage assessment.

The brief requirements are: • Wheat and barley crops are of most interest to us.

• Access to yield data from the last 5 years or so. Ideally since 2017 (since Sentinels 2A and 2B are both in operation).

• Indication if guidance was used at harvest. We can then generate an elevation layer from the yield data.

• Shape file or KML of Paddock boundaries so we can generate Yield maps.

• Proximity to the community weather station is desirable, but not crucial.

• A time series of yield maps of the same crop, so we can identify anomalous yield patterns.

• Polygons of where frost was identified on the ground (both cut-for-hay on not-cut-for-hay).

• Polygons showing strip trials and/or variety change locations to avoid false detection.

All the data will be anonymised and will only be used for this research purpose. If you are interested to participate please contact uday.nidumolu@csiro.au / christina.ratcliff@csiro.au

MicroClimate As part of this project, farming systems groups are measuring frost at head height, this is a valuable measurement as it is closest to where the damage is occurring.

The figure below is from the Tooligie frost site on Eyre Peninsula which is about 50km north of Cummins. A local agronomist, Michael Hind points out that Tooligie is frostier than Cummins.

The grey line is minimum temperature from Cummins airport, the orange line is from the paddock at Tooligie but where a data logger is placed in a ‘bee hive’ type cover at 1.2 m. The blue line is an unshielded data logger at head height in the crop.

This graph reinforces the point that where we measure the temperature matters. The paddock at Tooligie (orange line) is colder than Cummins airport (grey line) and crop at head height is approximately 2 degrees colder.

From the 14th to the 19th of August the lines more or less track each other. Later in August on the very cold night of the 27th it was 0.6 degrees at Cummins, whereas the paddock at Tooligie dropped to negative 3.2 degrees (1.2 m shielded) and the crop was a damaging -6 degrees.

There are 9am wind readings for Cummins aerodrome and it was calm on 25th, 4km/hr on 26th and 19km/hr on 27th.

Phyloclimate

Researchers who study freezing in plants report surprising results such as the plant can freeze from the lower leaves first and that the process of freezing seems almost random.

They also identify that the relationship between temperature and frost damage can be quite weak.

This is in part due to super cooling of water.

Dr Troy Fredrickson from QDPI poses the question at meetings “What is the freezing point of water” and most of us give the wrong answer of zero degrees. Zero degrees is the melting point of ice, but water can supercool and stay in liquid form well below zero.

Dr Ben Biddulph from DPIRD (WA) is investigating the role of ice nucleating bacteria that might explain why some plants freeze at different temperatures – a case of “watch this space”.

Concluding remarks Simply going for a walk on a still evening reveals that minimum temperature varies across the landscape because the human body is sensitive to small changes in external temperature.

While we don't have today's quality weather data for past measurements, we now have access to more weather stations and relatively low-cost data loggers.

Information from CSIRO on temperature across the landscape is a way of using the data loggers. This information combined with yield maps has the potential to help with frost zoning and scouting for frost damage.

Commercial and research developments in remote sensing of frost damage is increasing the level of information that is immediately beneficial for making decisions on cutting frosted areas for hay and adds to the overall picture of where frost occurs for long term planning.

Contributed by Peter Hayman, Dane Thomas & Bronya Cooper, SARDI Climate Applications.

Reducing the impact of frost with variety selection Ag Innovation & Research Eyre Peninsula

The EP Tooligie frost site sown 26th May by EPAG Research is looking to answer the following questions: Did sowing wheat varieties of different maturities sown on the same date reduce the impact of frost?

Did sowing a mix of maturities in a single crop reduce the impact of frost?

The varieties include: Vixen - early Rockstar - mid late Denison - late spring LR Awnless wheat Mixture Spartacus - barley Mace - early mid

All treatments have grown well and by September 10th the barley was out in head and the wheat was still in earlier growth stages, which was consistent with surrounding wheat crops in the district. There were no observed impacts due to frost, visual or dissected.

The site has since experienced multiple below zero conditions, with the most recent event in early October seeming to cause extensive frost damage (little to no damage reported prior to these events). All wheat varieties were impacted, with the barley appearing to fare much better.

The October frost events will be explored in more detail in the next issue.

There are now 5 Tiny Tag data loggers at the site to monitor temperature and the table below shows the minimum temperature information that has been downloaded from the tiny tags at the Tooligie site.

The Lock/Murdinga/Tooligie farmer group visited the site on 10th September with approximately 45 farmers attending the event. A summary of the temperatures aligned with growth stages so far was presented by Naomi Scholz, AIR EP. Michael Hind (Bates Ag Consulting) provided information on identification of frost and management options (reducing frost risk and dealing with frost affected crops).

Lock/ Murdinga/ Tooligie farmer group visit to the Tooligie frost site

Weekly monitoring by Rhaquelle Meiklejohn (EPAG Research/ SAGIT intern pictured right) has commenced, with Scepter growth stages recorded and aligned with below zero incidences according to loggers at the crop canopy height and logger in Stevenson screen.

An evaluation conducted of primary producers visiting the site showed 41% sometimes deal with frost and 55% deal with frost every year or most years. The usefulness of frost information presented at the site, rated highly.

For more information contact Naomi Scholz eo@airep.com.au

Photo Andrew Ware EPAG Research

Daily minimum temperatures from July to November for the last 3 years Eyre Peninsula Using a selection of EP sites with temperature observations, the tables show the daily minimum temperatures from July to November over the last 3 years. Overall, the pattern of daily highs and lows are similar across the stations, but the temperatures can vary. Kyancutta (green line) stands out as often cooler than other sites shown.

Daily minimum temperatures during 2019, 2020 and 2021 (until 15 Sep) recorded at Minnipa, Kyancutta, Cleve, Cummins and Port Lincoln on the Eyre Peninsula, SA.

20

2021

15 10 5 0 -5

01-Jul 08-Jul 15-Jul 22-Jul 29-Jul 05-Aug 12-Aug 19-Aug 26-Aug 02-Sep 09-Sep 16-Sep 23-Sep 30-Sep 07-Oct 14-Oct 21-Oct 28-Oct 04-Nov 11-Nov 18-Nov 25-Nov

Minimum temperature °C) (

25

MINNIPA

KYANCUTTA

CLEVE

CUMMINS

PT LINCOLN

Can you diagnose frost symptoms with confidence?

Frost Identification Guides produced by the Department of Primary Industries and Regional Development, with co-investment from the Grains Research and Development Corporation are available online.

These guides have been recently updated and include details on when to inspect crops and how to identify frost damage at the different stages of plant development.

https://bit.ly/3uWylnT

Creating frost zone maps for timely decision making Upper North Farming Systems

The site chosen for the Frost Extension site is Todd For some growers that are logistically set up for Orrock’s property at Murraytown in the Southern hay operations, the decision to cut a frost affected Flinders Ranges. Jessica Koch, Breezy Hill Precision crop can be simple. However, on many occasions, Tagfor Todd, he is very much geared towards a Ag Services, is assisting with the management of the Tiny like temperature sensors site, as she is developing a fact sheet on ‘Using grain harvest operation. simple map layers to practically manage frost’ using paddock showing In a season like 2021, whenMap the of hay market isn’t the spatial data layers that have been processed for Tiny Tag location strong, and grain prices are firm, a hay cutting in different zones Todd in PCT AgCloud over several years. decision needs to be accurate and timely to leave ‘Woolfords’ paddock is 195ha and highly undulating with 50m elevation gain from the low-lying frost prone areas up the ridges that rarely encounter a frost event. It is situated in a productive grain growing region with an average rainfall of 425450mm.

The field has a significant paddock history of frost, confirmed by yield maps and satellite imagery and crop scouting for inspection. The low-lying areas are affected by frost in September or October to some extent in 80% of seasons.

The purpose of the project is to show how easily accessible elevation data, and the sub layers that are available with elevation data (such as landscape change maps) can be utilised for managing frost events at hay cutting and harvest time.

as much unaffected grain crop standing for being harvested.

Elevation is an obvious driver to pinpoint frost in this field. Elevation data is collected by machines using RTK technology and this data can be easily processed and compared against other map layers such as yield and elevation, which Todd has done in previous years to make ‘hay cut prescription maps’.

Other ‘bonus’ map layers that can be processed from elevation data are Landscape Change (localised contours, creeks and depressions), Aspect (North, south, east or west facing) and Slope (steepness).

In this process, we are interested to see whether these layers are helpful in further capturing the detail of frost location and severity when it occurs.

Above– Elevation data for ‘Woolford’ paddock on the left presented in PCT AgCloud. The ‘bonus’ layers – ‘Landscape Change’, ‘Aspect’ and ‘Slope’ can also be ‘processed’ as layers from elevation data.

On July 29th, ten iButton temperature sensors were placed in strategic locations in the field mounted at 1.1m using a landscape change map as a background layer.

Left- Data from the iButton sensors being downloaded at the end of August with Mt Remarkable in the background.

The sensors are recording a value every 20 minutes and need to be downloaded monthly to extract the data and clear them to start recording for the next month.

Below - An example of the graphs downloaded from the most western placed iButton sensor indicating several frost events for the month of August.

Jess Koch has downloaded the first batch of data for August and the contrast in temperature from the bottom of the paddock to the top is stark.

For August, the eastern sensors on the ridges have recorded very little or zero incidence of temperatures below zero degrees. On the western side of the field, for the month of August, there were 17 occasions when the temperatures dipped below zero degrees for an extended time period (up to 8 hours).

Monitoring the temperature reading from the sensors will continue right up until harvest. In 2016, the western side of the field was obliterated by frost on the 26th of October, which significantly reduced the barley yield.

Left - Landscape change map layer in the PCT AgMap software used to scout to the location of interest and record the locations of the temp sensor sites.

On the 1st of September three separate tiny tags were placed at the trial. One was at canopy height, one below canopy height and another enclosed and facing south.

The sensors are inter-row placed and are working alongside the sensors that are already present within the trial. The data from these sensors is yet to be analysed.

Bottom - The damage a late frost can do.

Imagery from 2nd September, showing healthy even biomass, compared with the yield data at the top indicating significant yield loss due to a frost event 26th Oct 2016.

Left - Tint Tags installed at the Murray Town demonstration site.

For more info contact Morgan McCallum morgan@unfs.com.au

How do Mallee growers manage frost?

Mallee Sustainable Farming

Three Mallee growers, Kevin Bond from Mannum, Darryl Summerton from Pinnaroo and Lachie Singh from Alawoona, discuss how they manage frost on farm and their wish list for frost research.

Have a listen as they discuss their experiences with frost, how they identify frost in paddocks, varieties, time of sowing and salvage options.

These YouTube videos were developed as part of GRDC's Frost Extension Project in 2020.

Frost Response Discussion Group Postponed to 2022 After a decile 1-2 season for most of the Mallee, the Frost Response Facebook group to be piloted in 2021 will be postponed to the 2022 season.

The lateness of crop germination due to the dry start has also pushed many crops out of the high risk window for frost.

Late frosts can still cause damage to crops in the Mallee, however the low yield potential from a dry season can impact on the viability of hay making.

The pilot Frost Discussion group will return in 2022 and be ready to provide growers with information and access to experts to advice in response to flowering frosts in the region.

For more information contact Tanja Morgan tanja.morgan@msfp.org.au

Daily minimum temperatures from July to November for the last 3 years SA Mallee Using a selection of SA Mallee sites with recent temperature observations, the tables show the daily minimum temperatures from July to Nov over the last 3 years. Overall, the pattern of daily highs and lows are similar across the stations, but the temperatures can vary.

Daily minimum temperatures during 2019, 2020 and 2021 (until 15-September), recorded at Renmark, Loxton, Karoonda and Lameroo.

Mitigating frost risk in a mixed farming system

Trial information Varieties sown

Birchip Cropping Group

BCG's frost trial site established at Watchupga, aims to assess the impact and economics of variety selection and management on production in a frost prone environment.

Flowering assessments are currently underway at the site and when heads are further advanced with filing, frost induced sterility assessments will be collected to determine the level of impact across the treatments Recovery from late grazing has been quite good considering seasonal condition, however the loss of the primary tiller due to grazing may impact yield given the dry seasonal conditions.

The site has had 20 days where the temperature dropped below 0 as of 16th September. Data on frost duration is yet to be analysed although the impact of low temperature is clearly visible on emerged heads in early sown and ungrazed plots.

A BCG Members Field Day September 16th with a presentation and crop walk at the frost trial. There were approximately 90 farmers and advisors who were taken through the trial.

Left - YouTube video with Genevieve Clarke BCG, presenting a tour of the frost trial site at Watchupga, VIC.

Daily minimum temperatures from July to November for the last 3 years Vic Mallee Overall, the pattern of daily highs and lows are similar across the stations, but the temperatures can vary.

Longerenong stands out as generally having the coolest minimum temperatures.

Daily minimum temperatures during 2019, 2020 and 2021 (until 15 September), recorded at Walpeup, Ouyen, Kerang, Charlton and Longerenong.

1. Illabo - mid developing winter 2. DS Bennett - slow developing winter 3. Scepter - fast developing spring 4. Razor CL Plus - fast developing spring 5. Vixen - fast-mid developing spring 6. Catapault - mid developing spring

Two times of sowing, 15 April and 7 May. Simulated grazing treatments to delay flowering.

Hay biomass and quality measures will be taken.

For more information contact Tom Draffen tom.draffen@bcg.org.au

Frost in South West Victoria Southern Farming Systems

Frost in South West Victoria varies greatly and is very unpredictable. As a general rule of thumb the Mininera region will receive a severe frost 1-2 times in 10 years, but have minor events affecting the low lying areas and headlands possibly more frequently; as much as 6-7 times in 10 years.

The district experiences both flowering and grain development frosts which are very late in the season, Late October - November.

The frost risk depends greatly on the topography and seasonal circumstances. The last ‘great frost’ occurred on the 8th November in 2017 and this event significantly affected yields in the district over two nights.

What we learnt from this event was how much sub soil moisture and plant moisture stress impacted the damage from frost. Even though the crops looked great and didn’t appear to be moisture stressed the sub soil was dry and with the added stress of frost conditions the damage was done.

This was also seen in the 2008 frost, where the plant density was higher on the headlands and using more moisture, and when frost conditions were present the headlands suffered the most with the rest of the paddock escaping damage.

The main management tools grower in the region have implemented to manage frost risk are: · Crop Type & Variety Selection – In high-risk areas a lot of people in the district tend to grow more milling oats in those paddocks and investigate the option of using winter type varieties. · Hay Production – Owning hay making equipment and infrastructure to store the product is a viable option and takes a lot of stress out of a major frost event knowing you can still have a return from that paddock.

Left SFS Streatham Branch Trial Site 27th August.

Canola flowering at different stages.

Take a look at "A Grower and Agronomists frost discussion in the High Rainfall Zone" that highlights the practical considerations of frost management.

How is the season travelling?

After a wetter and cooler than average summer, the soil moisture probes showed around 80% PAW in April.

This created a fantastic start to the season and the rain has continued making it hard to get appropriate in crop applications done and some waterlogging damage has occured in low lying areas. So far, the season is tracking just above decile 5 (see table below) for the Streatham region and soil moisture probes are reading between 80-95% PAW at mid September.

The crops are a little uneven due to the wet and possibly lack of nutrition at the right time. Disease pressure is about normal across all crop types. We have been lucky so far with frost conditions to date.

For more information contact Michelle McClure mmclure@sfs.org.au

Frost Learning Centre in the Mid North SA Agrilink Agricultural Consultants

A Frost Learning Centre (FLC) has been established at Farrell Flat in the Mid North, where research is conducted by Mick Faulkner and Ben Smith from Agrilink Agricultural Consultants for the Mid North High Rainfall Zone group with investment from GRDC, SAGIT, GO Resources and Agrifutures and Agrilink.

The FLC has frequent and severe frosts with one site located on a more prone flat and a comparative site located on a rise, some 25m more elevated in the same paddock.

It has been designed in a way that the hill site acts as a control for some trials and so the impact of frost alone can be determined. In addition, frost exclusion structures are used to help determine what the impact of frost is when responses inside the shelters are compared to those outside.

12) variety comparison, herbicide tolerance, time of sowing and management of Super High Oleic Safflower, 13)biomass production in cool vs cold environments, 14)identifying the role of stubble in air and plant temperature, 15)the role of canopy, pulling apart plant population and nitrogen rate in frost damage, 16)collaborating with CSIRO in the FrostSense project to investigate topographical correlations and using satellite technology for potential of accurate, rapid identification of damage, 17)collaborating with COtL in accurate landscape temperature modelling and measurement 18)applying ice nucleating compounds to enable freezing when supercooling occurs.

What is being investigated at the FLC? The FLC is extensive in its outlook and is researching 1)temperature logger placement and accuracy, 2)using thermal imagery to measure plant temperature and treatment responses, 3) phenology development and frost damage of wheat, barley & oats, including varieties and time of sowing, 4)variety comparisons, 5)single sowing, variety mixing and intercropping of wheat, 6)delaying and resetting crop maturity by mechanical, simulated grazing and plant growth regulators, 7)single sowing and intercropping of lentils, faba beans, barley, and canola 8)using PGR’s (GA enhancing and GA inhibiting) on wheat varieties with different rht genes, 9) thermography and spectral imagery to identify frost damage in leaves, heads, anthers, and grains (handheld spectrometers and satellite), 10)comparing the grain and hay yield & quality of potential dual-purpose wheat and barley, 11) spring sown, photoperiod and vernalisation responsive pulses,

Mick Faulkner and Ben Smith at the Farrell Flat frost learning centre with Dane Thomas and Peter Hayman, SARDI and Morgan McCallum, Upper North Farming Systems.

Intercropped DS Bennett and Denison

Mixed DS Bennett and Denison

There are a range of different management options to reduce or minimise frost damage and losses. While the FLC is in a high rainfall area, most research and tactics can be adopted by anyone who experiences frost.

The FLC is targeting researchers, farming systems groups and advisers to better understand frost, how to conduct research and what extension messages will assist farmers who have frost as a constraint.

Understanding the drivers of frost damage Preliminary results are proving that frost damage is not a simple predictable outcome based on topography, weather predictions and simple modelling.

Essentially frost isn’t frost, and there is a lot of complexity, much of which is yet to be unravelled.

One of the major problems is that the damage is occurring in the plant, yet the measured temperature is of air, often a long way away, at a different height or in different environment (e.g., above bare ground). A good analogy of this is trying to predict how many individuals in a population of people will be sunburnt based solely on the UV index announced in the forecast.

It is often thought that frost occurs when, or because, there is a no air movement and cold air ‘settles’ in the crop canopy but data loggers and high integrity weather stations such as the Mesonet have shown there is basically air movement occurring all the time.

Radiative heat loss is the driver of frost development and the complex interchange of cold air, due to this loss, is what provides the lower temperatures that predispose frost occurring. However, frost doesn’t always occur when temperatures reduce because plants supercool, and microclimates mean air temperatures can vary considerably over very small distances (cm not metres).

So, damage occurs because of plant parts freezing, not the temperature of the air. These are two quite different things although there is a relationship between the two.

Thermography indicates the actual temperature of plants, and their parts, and is a necessary step in bringing accuracy to any sort of damage function. Even with thermography it is evident that plant tissue does not freeze at the same temperature time after time. It is a complex science and reliant on ice being formed, which requires some sort of nucleating agent. Otherwise, wheat plants have been known to tolerate temperatures below – 10 degrees.

A key to try and understand the frost effect on crops is to understand how a frost works through the night, length of time, air movement, radiative losses from soil and plant.

Topographically frosts tend to be in the lowest points of a paddock or where air movement is held up by physical barriers (trees lines, fence lines, embankments etc).

This research has involved the laborious task of putting effective frost shelters over plots and thermal imaging crops at night during frost events. Simple frost shelters do not guarantee frost protection and Mick has researched shelter design and constructed shelters that this year have been effective at very low temperature.

The 'Zone' approach to frost management It important to understand that frost damage impacts some farmers more than others and that each farmer has paddock or farm zones that delineate their need to adopt frost strategies.

For example, if a property has no frost risk and the business isn’t impacted at all by frost then they are operating in a ‘Frost Green Zone’. There is no need to adopt any frost mitigation or avoidance strategies, and to do so would severely reduce its ability to push production or yield and grow high value crops.

However, if a property has areas that are frequently or savagely damaged by frost then they are ‘Frost Red Zones’. If this farmer adopts what he is doing in the Green Zone and simply does the same in the Red Zone, then it is likely that large losses will occur.

So, the big impact is the size of the Red Zone compared to the Green Zone. It is therefore necessary to firstly identify, and then manage, the Green and Red Zones quite separately.

Kraken hooded barley

Safflower

Of course, in between the Green and Red Zones is an area, which we call the Amber Zone, which sometimes gets frosted (always when the Red Zone is severely frosted) but mostly doesn’t and has production capability like the Green Zone.

It is also very important for researchers and advisers to drive their efforts to Red, Green or Amber Zones. GRDC NVT data, for example, is very useful for making variety decisions for Green Zones but has no relevance at all for a Red Zones.

Zones then become the driver for management decisions and some of the following research that is underway based around crop phenology, flowering time, stubble cover, crop choice and crop canopy.

Farmers, researchers, and agronomists in frost prone areas ought to be able to identify frost damage in a range of crops to make management and economic decisions.

Plant phenology and growth stage are important, but in many regions, frost can occur over a wide risk window.

Just avoiding flowering frosts is often pointless as stem frosts, head frosts and frosts during grain fill lead to major crop losses. In fact, there is plenty of evidence that flowering is no more susceptible than these other stages.

Pulses are perhaps the best indicator of this where losing a few flowers is no risk when compared to losing pods.

In summary, the frost learning centre is an invaluable resource currently investigating lots of different aspects of crop management for frost mitigation. Given favourable results these strategies are farmer ready and provide a range of options that can be implemented across a farm or in frost prone zones.

Frost will continue to be a hard issue for growers as there is no 'silver bullet' solution, but research is ongoing to better understand frost damage functions and identify more practical strategies for growers to implement. The next step required will be to replicate these trials over a number of seasons and rainfall environments.

For more information contact Mick Faulkner mick.faulkner@bigpond.com