Crop topping timing important for pulse quality
Grain growers are being advised to be strategic about crop-topping this year’s pulse crops.
Pulse industry authorities, supported by the Grains Research and Development Corporation (GRDC), say crop-topping too early can affect pulse grain quality and potentially result in higher visible mould on grain.
Crop-topping is the application of a non-selective herbicide prior to harvest when the target weed (often ryegrass) is at flowering. The practice is also used for pre-harvest desiccation of a crop to accelerate or even up ripening to assist with harvest.
Pulse Australia’s Wayne Hawthorne says research by the South Australian Research and Development Institute (SARDI) indicates that timing of crop-topping may be important in reducing the risk of mould in pulses. If the practice is undertaken too early in some crops, the risk of mould developing on pulse grains is heightened.
Mr Hawthorne says the research conducted by the SARDI New Variety Agronomy group has also suggested that some parts of paddocks or wheel tracks are not as mature as the remainder of the crop when crop-topping is undertaken, leading to potential seed staining and increased incidence of mould in those areas.
Speaking at recent GRDC grains research Updates, Mr Hawthorne said SARDI research had shown that longer-season lentil and field pea varieties were less-suited to crop-topping and seemed to be more prone to yield and quality loss with early crop-topping.
“Short-season varieties such as PBA Blitz or PBA Flash lentils, and PBA Twilight PBA Gunyah or PBA Percy field peas are more suited to crop-topping than their longer season counterparts Nugget lentil or Kaspa field pea,” said Mr Hawthorne, who is a Pulse Industry Development Officer with Pulse Australia.
“Chickpeas are not suited to crop-topping because of their late maturity, and faba bean varieties can be too late maturing for timely crop-topping in seasons with a better finish, and we have no short-season varieties available.
Product used and rate of application for crop-topping could also have major implications, so growers should follow label directions for use.
Growers are reminded paraquat that is registered for use in pulses is not registered for use in cereals and canola, and if glyphosate is applied to desiccate the crop, the grain should not be used as seed for sowing.
Label directions must be followed at all times and growers should carefully note withholding periods prior to harvest.
Mr Hawthorne said seasonal conditions, particularly rain just before harvest, could also have a significant impact of the quality of pulse grains, as was experienced just before harvest in 2010-11.
A nil tolerance to mould will again apply to pulse receivals during the 2012-13 harvest. It had been hoped by some industry stakeholders that a “low tolerance” to mould in pulses at delivery would have been implemented this season.
Mr Hawthorne has advised that an industry-wide discussion on a potential revised definition and/or tolerance for mould in all commodities will be conducted by Grain Trade Australia in developing the 2013-14 standards.
Meanwhile, an updated GRDC Late Season Herbicide Use Fact Sheet is included in the September/October edition of Ground Cover magazine, offering growers of pulses and other crops advice on stewardship for late season application of herbicides in winter crops.
The fact sheet is also available for viewing and downloading via
Caption: Pulse Australia’s Wayne Hawthorne, pictured at a recent GRDC grains research Update at Kadina in SA, says research by the SA Research and Development Institute has shown that crop-topping too early can affect pulse grain quality.
Media releases and other media products can be found at www.grdc.com.au/Media-News
Interviews: Wayne Hawthorn, Pulse Australia
Contact: Sharon Watt, Porter Novelli
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