Time of sowing trials in New South Wales in 2014 showed that despite widespread frost damage, early-sown crops in most cases were still able to match main season crop yields.
CSIRO research team leader James Hunt said the results confirm that early sowing has a place in modern farming systems.
“The 2014 season was unprecedented in terms of stem frost damage, with the Junee trial site experiencing 18 stem frost events and 75 frosts in total, and while the early-sown crops did not out-perform main-season wheats, the results were not too bad, and it was the first season in a very long time where early sowing was not by far the most profitable thing to do,” Dr Hunt said.
Trial sites at Rankins Springs run by AgGrow Agronomy and CWFS and at Junee run by CSIRO and FarmLink research monitored the performance of crops sown in mid-April or mid-May.
The Rankins Springs site had an 18-month fallow and highest yielding treatments were winter wheats including EGA Wedgetail and Osprey sown in mid-April, with 5.7t/ha achieved from both cultivars. The best performing spring wheat, Gregory, achieved 4.7t/ha when sown in mid-May.
At Junee, winter wheats sown on April 7 yielded lower than spring wheats sown on May 21, with Gregory achieving 3t/ha compared to 2.5t/ha from Wedgetail. However the highest overall performers were winter wheats Wylah (3.7 t/ha) and Whistler (3.6 t/ha) sown on April 24.
“The winter wheats sown in early April were affected heavily by stem frost and Barley Yellow Dwarf Virus. The April 24 sowings were still hit by BYDV but avoided stem frost, so were able to perform far better,” Dr Hunt said.
While 2014 was a particularly difficult year for early-sown crops, Dr Hunt says that is no reason to think it will not happen again.
“We have to learn from what we can from 2014 in order to manage these risks in future. Learnings that growers can take away are that if sowing before April 20, winter wheats are at lower risk of frost damage because they are slower to move from vegetative to reproductive growth and have higher frost tolerance than spring wheats when in the vegetative stage,” he said.
“A lot of the crops severely damaged by frost were spring cultivars sown much earlier than their optimal sowing date, so if growers can plan their sowing program so that spring wheats are kept within five to seven days of their optimal sowing date, frost risk will be reduced.
“Finally, it can be a good idea on early-sown wheats to follow up seed dressings with foliar insecticides if aphids are a concern, to reduce the risk of BYDV damage.”
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Long season wheats pose stem rust risk
The risks of developing stem rust in longer season winter wheat crops are being highlighted as New South Wales wheat growers begin to prepare for the 2015 growing season.
Plant pathologist at the South Australian Research and Development Institute (SARDI) Dr Hugh Wallwork, who is part of the Australian Cereal Rust Control Program with New South Wales Department of Primary Industries Dr Andrew Milgate, said growers needed to be aware of the susceptibility ratings of the long-season wheats and to ensure they plan appropriately to manage any rust outbreaks.
“Some of the longer season winter wheats are attractive for their high yield but the problem is that some of them have susceptible or very susceptible ratings to stem rust and this is made worse by a greatly shortened break between crops over summer in the long season cropping areas,” he said.
“Rust needs a green living host, often called the green bridge, to survive between the seasons. Normally this is in the form of volunteer cereals growing as weeds, however, in the areas where these long season wheats are grown, the natural summer break between crops is greatly reduced. This therefore requires greater monitoring and rust management planning to prepare for any potential outbreaks.
“Stem rust is the most difficult of the three types of rust to control with fungicide as it is difficult for foliar fungicides to penetrate the canopy and protect the stem.”
Dr Wallwork advised that growers choosing a long-season wheat obtain information on that variety’s susceptibility rating from the breeding company or their local advisor before seeding and ensure they have an effective stem rust monitoring plan in place.
“There are other long-season wheat varieties available that have a higher stem rust resistance rating, including Bolac, Forrest, EGA-Wedgetail, Manning and SQP Revenue, and we recommend that growers should, if possible, look to growing these or others with stem rust resistance in the next season,” he said.
Cereal disease variety guides can be found at the RustBust website
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