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Australian Herbicide Resistance Initiative (AHRI)

AHRI’s top performing insights and podcasts for 2019

Tag Archives | herbicide resistance

Australian Herbicide Resistance Initiative (AHRI)

2,4-D resistance does not affect the fitness of radish

Merv Hughes was not a fit-looking cricketer. Merv was a notorious consumer of food and alcohol, and it showed! Despite this, he was a successful professional sportsman. Mitchell Johnson, on the other hand, was the epitome of a fit, healthy fast bowler. But who had the better bowling average? You guessed it, big swervin’ Mervin!! 28.38 compared to Johnson’s 28.4. Ok, we’re splitting hairs here, but you get the picture, how fit you look is only part of the story. If you grew 2,4-D resistant radish in pots on its own, and compared that to the good old susceptible radish…

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Australian Herbicide Resistance Initiative (AHRI)

Trending now: herbicide resistance management

‘Trending now’ seems to be everywhere – iTunes, Twitter, the news, so why not herbicide resistance? What have been the #Top5 trends in resistance management over the past decade? As a young agronomist 20-something years ago (clearly before trending was a thing), I remember learning about the threat of herbicide resistance as if it was a kind of apocalypse. Some growers were genuinely concerned that they wouldn’t be able to continue farming. We’ve come a long way in a relatively short time. In this insight, we look closely at what’s trending in the herbicide resistance management space.

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Wild radish flower

Australian Herbicide Resistance Initiative (AHRI)

Is there an invisible gorilla in your paddock?

Huan Lu’s been investigating a population of wild radish that has the infamous Ser-264-gly mutation. This is the target-site mutation that is behind TT canola and makes wild radish highly resistant to PSII-inhibiting herbicides like atrazine and, to a lesser extent, metribuzin. But, he wondered if there was more to this resistance than first meets the eye. Does focusing on the strong 264 mutation mean that we could fail to identify other important resistance mechanisms?

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Australian Herbicide Resistance Initiative (AHRI)

Thermal weed control – just hot air, or site-specific reality?

Did you know that rotary hoeing requires less energy than steaming? Or that offset discing requires less energy than microwaving? Well, that’s the case when it comes to controlling weeds. An epic effort to review 170 papers by a team from the University of Sydney (Guy Coleman et al) has shown that mechanical weed control options (eg. tillage) can use significantly less energy than thermal options (eg. heat) to kill weeds. Herbicide energy use sits somewhere in the middle.

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Australian Herbicide Resistance Initiative (AHRI)

Keep mixing herbicides

Roberto recently completed a project with GRDC investment where he sampled ryegrass from 17 paddocks across eight farms in Western Australia to see if there are benefits of proactively testing for herbicide resistance.  Across these tests, he found ryegrass that was resistant to Clethodim (Select) or Butroxydim (Factor) but no ryegrass that was resistant to the mix of the two. The same went for the pre-emergent herbicides as well, no resistance to mixes.

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Australian Herbicide Resistance Initiative (AHRI)

Twenty five years of testing annual ryegrass resistance – it’s a numbers game

Charles Sturt University has sown, sprayed and counted annual ryegrass from around 12 million seeds submitted from more than 5000 samples sent in from across Australia since it started testing for herbicide resistance in 1991…and that’s just ryegrass. Mind numbing stuff. But more than 5000 ryegrass samples? Most tested to five or six herbicides? Think about the value of that information! Dr John Broster and Professor Jim Pratley from CSU have analysed the data from ryegrass samples sent to the testing service over the 25 year period from 1991 to 2015.

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Australian Herbicide Resistance Initiative (AHRI)

Trifluralin resistance is different – recessive inheritance

We once thought that the genetics of eye colour was simple. Both parents have blue eyes, therefore, all of their children will have blue eyes. Easy peasy! Then science progressed and we realised that it isn’t actually that simple because several genes are involved. The genetics of herbicide resistance was simple. One parent is resistant to a herbicide, therefore, all of the offspring will be resistant because the gene is dominant or semi-dominant. This is true for almost all cases of herbicide resistance and was easy to understand. Until now. Click to read more about PhD student Jinyi Chen’s research.

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Australian Herbicide Resistance Initiative (AHRI)

Are ‘pre-ems and crop competition’ the ‘wine and cheese’ of weed control in canola?

Wine and cheese. Strawberries and cream. Crop competition and pre-emergent herbicides. Ok so the last one doesn’t quite have the same ring about it but they really do go together nicely. Combining a competitive canola variety with pre-emergent herbicides has proven to be an effective strategy for reducing annual ryegrass seed set. Recent trials showed that with effective pre-emergent herbicides, a competitive hybrid canola variety can reduce ryegrass seed set by 50% compared with a less competitive open-pollinated (OP) variety. That’s impressive. But should we tar all OP varieties with the same brush?

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Australian Herbicide Resistance Initiative (AHRI)

Chickpeas can compete

There are few herbicide options for sowthistle control in chickpea crops, making the perfect recipe for a good ol’ sowthistle blowout. Despite all of this, the latest research by Michael Widderick, Adam McKiernan and Greg Harvey from QDAF with GRDC investment is finding that chickpeas can win the competition against sowthistle if they stack their deck. Growing a chickpea crop at narrow row spacing and high crop density in northern cropping regions can greatly reduce sowthistle seed production without reducing chickpea yield. Click through to find out more!

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