Spring has sprung across our cropping regions with many canola paddocks near to full flower, and other crops not tailing too far behind.
The clear and calm nights that are common during spring are perfect conditions for frost events to occur. The Wimmera and Mallee regions have been experiencing frost events over the past few weeks with some damage already evident in crops, causing potential yield losses during the high risk flowering period.
CSIRO analysis has shown a trend towards an increase in the length of the frost season with more frost events occurring each year. Knowing this trend, understanding frost risk, identification of damage and management are an important set of skills for growers to have now more than ever.
BCG has been involved with the GRDC-funded National Frost Initiative (NFI) over the past four years, a national project aimed to provide information and management solutions for frost in crops to help maximise seasonal profit.
This year, BCG is managing two frost trials looking at the effect of crop type and time of sowing, and sowing rate and nitrogen management in wheat located at Corack and Murtoa, respectively. Monitoring at these sites has shown very cold temperatures have been experienced by crops in frost prone areas of these paddocks. Observations of a 2-4˚C difference between temperatures logged at the weather station and at crop height, the latter experiencing colder temperatures (1.2m lower to the ground).
Frost prone areas of paddocks are lower lying in the landscape due to the nature of cold air to pool and settle. In many cases frost damage occurs in isolated patches across a paddock but can cause more widespread damage in certain paddocks, or in more uniform landscapes.
BCG senior research officer Kelly Angel said the severity of a frost event can be determined by the speed at which the temperature drops to below zero, how low the temperature gets and how long it is held below zero for.
Ms Angel said “Another contributing factor is soil moisture level. When there is little soil moisture the risk of frost damage is increased as moisture can help to increase the heat storage capacity within a soil, and the ability of the crop to cope with a frost event.”
“However, if a crop canopy is wet from a light shower it can be more prone to frost damage than one which is dry, due to the presence of ice nucleators such as dust or bacteria,” Ms Angel highlighted.
The BCG frost trial site at Corack has experienced widespread and severe frost damage across the trial and the Murtoa trial, further behind in maturity, is not yet showing signs of severe frost damage but is by no means past the high risk period.
Monitoring crops, as has been done with these trials is a key to identifying when damage is occurring with plants able to be affected by frosts all through the growing season to varying degrees. These trials are being assessed for biomass, NDVI (crop greenness), tiller numbers (Murtoa only), frost induced sterility, yield and grain quality to help gather a better understanding of frost and steps that can be taken to manage the risk in season.
To find out more about frost risk, damage and management come along to the BCG Main Field Day on September 13 at the main research site at Curyo (25km North West Birchip on the Sunraysia Hwy). There will be experts running through what to look for when assessing frost damage on a variety of plants from the local area that have already experienced damage. For more information on this research or the Main Field Day phone the BCG office on 03 5492 2787.
