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FARM SERVICES | 1 January 2010

New tool to control resistant ryegrass and boost productivity

Herbicide resistant annual ryegrass was a major headache for Wimmera grower Dean Wallis, until he made a slight change to his crop rotation and herbicide program.


The simple solution to his ryegrass problem came in the form of Roundup Ready (RR) canola, coupled with the latest advice on how best to use it to control weeds and boost productivity.


“We normally use triazine-tolerant canola varieties in our crop rotation, but found ryegrass becoming a major problem over the years,” Dean said.


“To help control the ryegrass we now have to break our crop rotation and grow pasture or a legume.”


“By planting RR canola we can control ryegrass in that phase of the rotation, and not have to miss a cropping year.”


The crop management details needed to successfully control ryegrass with this latest canola variety were incorporated into Dean's PaddockWise program by Landmark Kaniva agronomist, Tristan Rogers.


“Dean has been farming in the district for over 40 years, and like many growers near Kaniva, was having major problems controlling annual ryegrass,” Tristan said.


“By sourcing seed for him last season to establish a trial area of 35 hectares, we were able to help Dean regain control of the ryegrass problem in some of his worst-affected paddocks, and boost productivity.”


According to Tristan, management practices for RR canola are different to other canola varieties.


“Because it's possible to spray glyphosate over the emerging canola crop to control ryegrass and other weeds, RR canola can be sown very early,” he said.


“Early sowing gives the crop a big yield advantage once the season breaks, as does being able to control weeds as they emerge and before they compete with the crop.”


According to Tristan it is safe to spray glyphosate over RR canola from emergence to the six-leaf growth stage, and for best weed control, to wait until the weeds have grown two or three leaves.


“You may need to spray a second time two or three weeks later to control any weeds that germinated late or were too small the first time,” he said.


Dean said that with dry weather conditions (receiving only half the normal rainfall), he averaged just 0.25t/ha from triazine-tolerant varieties last year. However, thanks to early sowing and better weed control, he achieved 1t/ha from the RR canola trial, and an increase in the seed oil content.


“We have benefited significantly from our revised management program,” Dean said.


“Not only has Tristan helped us control annual ryegrass, we are now growing a profitable canola crop, and we have increased our productivity by not having to break our rotation purely to control ryegrass.”


To achieve those yields and the higher oil seed content, Dean had to pay close attention to nutrition and timing.


“Our PaddockWise program includes crop rotation information, yield data, and results from soil tests; and it identifies the correct fertiliser inputs needed each year. All we have to do is apply the recommended amount of urea at the right time; and in some soils, also add zinc,” Dean said.


As a result of the great success with the trial, Dean has this year planted 100ha to RR canola, which now forms a key part of his crop rotation to control ryegrass.

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