Southern region grain growers who have recently experienced frost events are being advised to continue to monitor crops to determine the extent of damage.
Monitoring is required for up to two weeks after a frost event as symptoms may not be immediately evident.
Researchers involved in the Grains Research and Development Corporation’s National Frost Initiative (NFI) say monitoring and damage assessment are critical in informing crop management and harvest strategies.
Kelly Angel from BCG (Birchip Cropping Group) says recent severe frosts – such as the minus 3.1C recorded on October 10 2017 at Corack in a frost-prone part of the Victorian Mallee – are likely to have impacted on yields.
“With these frosts occurring so late in the season, there is little chance crops can recover,” said Ms Angel, a BCG senior research officer who has been conducting farming systems trials for the NFI.
“But it is still important to go out into the crops regularly and check for damage, especially given that growers are not always aware there has been a frost.
“Knowing what they are dealing with will help growers determine what to do with the crop, their priorities for harvest (get the unaffected areas of crop off first) and how they manage the residue of frosted crops.
“Decisions need to be made and growers need to be proactive in making those decisions.”
Ms Angel said that sometimes the most economical option for managing crops hit by late frosts was still to harvest them, either for hay or grain.
“If cutting for hay is not a viable option, growers need to think ahead about managing the residue – at the end of the day, the cheapest approach could be to put the header over it.”
After a frost event has occurred, a random sample of heads should be collected to estimate the yield loss incurred. Growers should examine the crop in the more susceptible lower parts of the landscape first and if the crop is damaged proceed to higher ground.
If a frost has occurred when crops are at the flowering stage, frosted anthers will be white turning a dull brown colour, ovaries will turn a dull brown and are spongy when squeezed. They begin to shrivel as no grain is developed. Also, the head will be underdeveloped and/or have bleached florets.
Frosted grain at the milk stage is white, eventually turning brown with a crimped appearance. It is usually spongy and when squeezed it doesn’t release a milky dough substance. Frosted grain at the dough stage is shrivelled and creased along the long axis, like a pair of pliers has crimped the grain in the middle.
After the level of frost damage is estimated, the next step is to consider options for the frost-damaged crop.
“Every grower is set up differently in terms of their farming systems and the management and salvage strategies available to them so each situation must be treated on an individual basis,” Ms Angel said.
She said in all cases, however, growers needed to carefully consider the economics of available options and should seek support and advice to assist with logical decision making and assessing the impact of a frost event on their business going forward.
“Frost is an unpredictable, high-impact condition that can create enormous stress for growers, especially at this late stage in the growing season.”