Frost insights revealed

Mr Faulkner and colleague Ben Smith co-ordinate the site, which was established through funding from SAGIT and the GRDC, on behalf of the Mid North High Rainfall Zone Group.

"There is nowhere else that is studying frost this comprehensively, with more than research or extension projects," he said.

"And it's not just for farmers to learn about frost, but also getting the methodologies and protocols right to do valid research.

"There are so many influences in any frost event, but there are also many things that influence how researchers get reliable information - obviously temperature is a key driver, but where we measure it, how we measure it, plant versus air temperature, and the relationship between temperature and ice nucleation - it is a very complex thing to measure."

Mr Faulkner said thermal cameras were the most effective way to measure the actual plant temperature, while special frost shelters had been refined for the project.

"We have spent the past five years designing an effective frost shelter, that doesn't require an external source of heat," he said.

"The aim of the shelter is to protect plants, even at air temperature that can be as low as -7 deg. Without shelters there really isn't a control treatment to determine responses.

"Shelters to be fully-sealed, easy to move, lightweight, shed water if it rains, made so they don't blow away, and be able to be placed and removed quickly by one person."

Mr Faulkner said the new Mid North mesonet had also been handy, as it measures wind speed using sonics. This type of equipment can measure wind speed approaching zero, unlike many weather stations.

Mr Smith was regularly on site measuring differences with the thermal cameras before sunrise.

"You have to record before the sun has its influence," Mr Faulkner said..

"But we believe we are getting enough information to say that some treatments we are working with are having an influence.

"We also now have ways to induce a frost, and with shelters, control a frost - we have never had that before (previously it has just been comparative treatments) so even in one year, this research has brought us so much."

One really interesting piece of the work is understanding how ice forms. Put simply, plants can tolerate temperature much colder than we ever experience in a frost (perhaps as low as -12 deg), but the damage occurs when ice forms. Without ice nucleation there isn't really much damage.

"We have been using insights from WA frost expert Ben Biddulph, who's research has found that temperature is just a precursor and not the prime driver of frost," he said.

"Plants can often tolerate down to -12, but it's when ice forms - nucleation - that's what does most of the damage.

"So we asked the question as to why does ice form? A pressure change can do it, but some of Biddulph's work has shown nucleation can be caused by the protein of a bacteria, more specifically pseudomonas bacteria - which is ubiquitous in Australia, but often not everywhere in a plant.

"In WA trials, it has been seen after a cold front passes with just a little bit of rain in it, then they get a still night - that's often when they experience the worst frost damage.

"This is probably because that rain is either picking up bacteria or dust, which are both nucleating agents, and depositing them on the plant, causing nucleation. Nucleation can be measured with thermal cameras as the process of freezing creates a small but measurable burst of heat.

"We applied a product similar to the pseudomonas bacteria that would induce the frost and we blitzed the crop - we now know there is definitely a relationship."

Mr Faulkner said finding a 'fix' for such as issue may prove difficult.

"Antibacterial spray products have been tried before on bacterial blight (another pseudomonas disease), without good results " he said.

"It might be where new genetics comes in, as there is natural variation out there for pseudomonas.

"Maybe removing older leaves, or those that will be the source of bacteria later in the season can reduce the amount of nucleating material.

"Farmers who graze their crops may not only be pushing out the flowering window, they may also be unknowingly minimising their risk by livestock eating older leaves."

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Grazing crops was just one of the many treatments researched at the site, along with intercropping, dual-purpose crops, variety mixes, spring sowing, stubble effects, plant growth regulators, and canopy and elevation influences.

"We even had a trial where we had 54 identical sown plots including one unsown, " Mr Faulkner said.

"This ended up being useful as we were able to analyse the variability across those 54 plots.

"The two highest yielding plots in the 54 were either side of that bare run, but there were also yield differences of about 2 t/ha between plots, yet they were identically treated. This indicates that plot yield differences were simply due to spatial variability. This insight means all frost research data might be difficult to interpret or even to get valid results

"And there is no doubt that bare soil influences crop yield in adjacent plots either because of air movement or for being warmer, or both."

While there has been many new insights gained from the project, Mr Faulkner said growers really needed to zone their properties into red, green and amber frost-prone areas to then manage accordingly.

"I've never really seen anywhere that a frosted area makes more money than an unfrosted area," he said.

"And until people start treating them differently, they're not going to win this battle.

"An obvious option might be to use a later maturing variety on their red zone areas, but not on the green zones as that variety probably won't provide the highest yield or quality where there aren't ever any frosts.

"Or if there is a plan to sow the same variety across a whole paddock, you need to manipulate your red zones at a certain stage, whether that's grazing, or by some mechanical intervention, which can prove difficult to implement. Doing something different at seeding time is much easier than manipulating later, unless there are plenty of sheep available.

"Why not change the variety to something like Bennett, a winter wheat, only on the red zone?

"Or maybe mix varieties, with different maturity drivers, other than temperature, like a photo-period responsive variety (Denison or Bale wheats)?

"Farmers could also tank mix something like Calibre in with Denison to get maturity differences into the vulnerable areas of the paddock.

"It is so hard to pick when the optimum flower window is going to be, or when frosts may occur, so at least having half the population potentially in a window when there aren't frost might mean there isn't total yield failure.

"I would even consider mixing three varieties, but we have yet to do any research on that."

Mr Faulkner also said the assumption that barley was more frost tolerant was also questionable.

"From our trials, the worst affected crops have been barley," he said.

"The best performing by a mile were oats .

"Oats can be susceptible to stem frost, but this could be more a bacteria than species issue.

"I was a skeptic about the bacteria concept, but when I saw thermal imagery, my mind was changed.

More research findings will be divulged during an upcoming Frost Learning Centre workshop at Farrell Flat on April 1.