Frost: no room for complacency
GroundCover™ Issue: 116
Western Australia had a frost-free season in most areas in 2014 and was perhaps lucky not to receive widespread devastating frost, which hit large areas of South Australia and Victoria.
However, this should not lull WA growers into a false sense of security, says Garren Knell of ConsultAg.
This was one of his key messages to delegates who attended ‘Pre-seeding frost workshops’ across the western region in March, which were convened by ConsultAg with support from the GRDC.
“Pre-season is the optimum time to consider strategies for mitigating frost,” Mr Knell says.
“Growers in frost-prone areas should never become complacent and should be constantly upgrading their toolbox for frost-mitigating tools and management strategies.”
Zoning the farm based on frost risk associated with experience from past seasons and managing the mix of enterprises, inputs and crop types according to the frost risk is an excellent strategy to reduce the overall farm business financial risk of frost damage.
Later in the season, there are fewer in-crop strategies to reduce frost risk.
However, being conservative with nitrogen in frost-prone paddocks can reduce risk and financial exposure, as crops with larger canopies suffer more frost damage.
“Reducing expenditure in frost-prone areas also minimises financial risk and can return competitive – if not better – gross margins, even if there are only minor frost events,” Mr Knell says.
“Crops deficient or marginal in potassium and copper may well be more susceptible to frost damage.
“However, supplying luxurious levels won’t buy any additional tolerance above adequate supply.
“In fact, preliminary GRDC-funded research is indicating there is no supporting evidence for the use of foliar-applied copper to mitigate the impact of frost damage in cereals.”
Southern WA trials have also shown that grazing wheat crops in winter to delay flowering can reduce grain yield losses from spring frosts.
This can be used as a tool to manipulate a crop’s flowering time after seeding and the key message is to graze early (at approximately the four-leaf stage) and graze hard for a short period. Fourteen days of grazing delays flowering by about seven days.
“Growers should be vigilant and inspect crops regularly following a suspected frost event and be aware of what potential salvage measures (such as cutting hay or brown manuring) are at hand for their enterprise if a crop is affected,” Mr Knell says.
He recommends growers keep an eye out for information being delivered by the GRDC’s National Frost Initiative.
“This initiative is taking a comprehensive, multi-pronged approach to frost mitigation for cereal growers and aims to deliver genetic, management and environmental solutions for growers,” he says.
The western region ‘Pre-seeding frost workshops’ were funded through the GRDC’s Regional Cropping Solutions Network (RCSN) and supported by the GRDC National Frost Initiative.
More information:Garren Knell
08 9881 5551
See here the latest information about National Frost Initiative projects and up-to-date frost information.
- Managing Frost Risk: a guide for southern Australian Grains
- Ground Cover TV, Frost Ratings project, episode 15, January 2015
- Zadoks Growth Scale
- Ground Cover Supplement on Frost
GRDC Project Code UA00136, DAW00241, DAW00234, TAR00004
Region South, West