Time of sowing trials run by SARDI in South Australia in 2014 showed that despite widespread frost damage, the highest yields still resulted from wheat sown in mid to late April.
CSIRO research team leader James Hunt said the results confirm that mid-maturing varieties such as Trojan can complement fast-maturing varieties such as Mace.
"Even in 2014, a year where frost was a major factor, sowing Trojan in mid-late April resulted in yields 16 percent higher than sowing Mace in early-mid May alone," he said.
Early sowing trials were conducted at six sites in South Australia – Cummins, Minnipa, Port Germein, Hart, Tarlee and Conmurra. At each trial site, three times of sowing were tested with the first in mid-April, one in late April/early May and another in late May/early June.
"What these data show is that in all cases Trojan sown early either matched or out-yielded Mace when sown in its optimal window of early-mid May (see Figure 1). This means that by starting Trojan ten days earlier than Mace, growers can benefit from its strong performance from earlier sowing and sow a higher proportion of their wheat program within its optimal sowing window," Dr Hunt said.
Figure 1: Mean yield performance (Minnipa, Cummins, Port Germein, Hart, Tarlee) of Trojan and Mace at different times of sowing relative to Mace sown in its optimal window of early-mid May. Error bars are standard error of means. Source – James Hunt.
Dr Hunt says an example sowing strategy could include:
- If May 10 is the optimal sowing window for Mace for a certain grower, and the grower has a 20-day wheat sowing program.
- Therefore the ideal sowing time for Trojan will be May 1 (10 days earlier).
- To sow half Trojan and half Mace, they should start Trojan on April 25, switch to Mace on May 5 and aim to finish on May 15.
- Under this strategy, all wheat is sown within five days of the optimal day.
The trials included winter wheats, such as EGA Wedgetail even though it has poor adaptation to many of South Australia’s alkaline soils and was not expected to perform strongly.
“We found that in some regions such as Hart, Wedgetail performed quite well, yielding 4.5t/ha when sown on April 14 compared with 4.7t/ha for Mace sown on May 8. However at other sites, it performed poorly. For example at Port Germein, the temperature does not get low enough for Wedgetail’s cold requirement to be satisfied, so it only yielded 2.5t/ha compared with 4.3t/ha for Mace and 5.2t/ha for Trojan,” Dr Hunt said.
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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 South Australian wheat growers begin to prepare for the 2015 growing season.
Plant pathologist at the South Australian Research and Development Institute (SARDI) Dr Hugh Wallwork 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 these longer season winter wheats are attractive for their high yield and are grown in the parts of SA that have longer and cooler seasons, but the problem is that some of them have susceptible or very susceptible ratings to stem rust,” he said.
“The problem is made worse by a greatly shortened break between crops over summer in the long season cropping areas.
“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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