Tag Archives | mechanisms

Australian Herbicide Resistance Initiative (AHRI)

Microbial degradation of propyzamide – will we have a problem?

Some excellent research conducted by Stephen Hole, under the watchful eye of Professor Steve Powles at the University of Adelaide in the mid-1990’s investigated the microbial degradation of propyzamide and another similar herbicide, carbetamide. Enhanced microbial degradation is where the soil bacteria that can eat a particular herbicide build up to very high levels so when the herbicide is applied it is broken down very quickly, effectively reducing the half-life of the herbicide.

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Australian Herbicide Resistance Initiative (AHRI)

Glufosinate resistance – we know what it’s not

“There are known knowns; there are things we know we know. We also know there are known unknowns; that is to say, we know there are some things we do not know. But there are also unknown unknowns – the ones we don’t know we don’t know. And if one looks throughout the history of our country and other free countries, it is the latter category that tends to be the difficult ones,” Donald Rumsfeld, US Secretary of Defense 2001-2006. Man, that’s deep! It’s wonderful for a scientist to have a hypothesis, do the research, and find that they were…

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Australian Herbicide Resistance Initiative (AHRI)

Wild oat resistance takes effort

Many young people don’t like the taste of beer, but they know if they work hard, endure the awful bitter taste and hideous hangovers for a few years, they will eventually like the stuff. It takes effort, but if they stick at it long enough they can get there. And, believe it or not, you have to work pretty hard to evolve resistance in wild oats. But if you stick at the same practice long enough (it takes effort), you can get there! We have previously reported AHRI research showing that wild oats evolve resistance slowly because they are both…

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Australian Herbicide Resistance Initiative (AHRI)

How stuff works: 2,4-D, free radicals and monkeys

It’s pretty amazing that 2,4-D is our oldest herbicide, yet scientists have only just worked out how it actually kills weeds. This has taken years of research by many researchers to understand. So, like the monkey Curious George, we set out to understand how 2,4-D works (trust us, click through to the full post and the monkey analogy will make sense!) 2,4-D works in three stages: first, it over-stimulates plant growth; second it closes the stomata and shuts down photosynthesis. And finally, the plant eventually starves to death as it works hard to detoxify the free radicals. In a nutshell:…

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Australian Herbicide Resistance Initiative (AHRI)

2,4-D Gridlock

Picture yourself as a city slicker driving to work. Between your house and the freeway there are four sets of traffic lights. On this particular day all of the traffic lights are stuck on red. The city is in chaos with no-one able to get to work. You then spend the rest of your life, in your car, at a red traffic light. Perish the thought! This is how 2,4-D resistance works in wild radish. The traffic lights are transporters that allow 2,4-D to move from cell to cell, and the freeway is the phloem – the plant veins that…

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Australian Herbicide Resistance Initiative (AHRI)

Canola’s a better crop plant than a weed

If our crop plants persisted in Australian bushland, our remnant vegetation would now be overrun with wheat, barley, canola, lupins, lentils (etc. etc.). Fortunately, this isn’t the case. Some recent research by Dr Roberto Busi confirmed that transgenic canola (Roundup Ready®) can persist in bushland, but only for three years. After this time, the insects, rabbits, competition and disease got the better of it and it died out. Road verges, on the other hand, are a different story. GM canola can persist on road verges largely because they are sprayed with glyphosate, killing all of the competition, allowing glyphosate tolerant…

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Australian Herbicide Resistance Initiative (AHRI)

Glyphosate resistant brome – gene amplification

Two years ago, a meeting was held in Australia to gather researchers who study weed, pest and disease resistance to see what they could learn from each other. There was a mind-blowing moment when an entomologist realised that the P450 enzymes he had been studying that gave resistance to an insecticide were the same as those that a weed researcher was studying that caused resistance to a herbicide (well… we thought it was mind-blowing. But then again, we’re weeds geeks!). Some new research by Jenna Malone, Chris Preston and others from the University of Adelaide weed research team have found…

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Australian Herbicide Resistance Initiative (AHRI)

Heal thy soil, heal thy crops, kill thy weeds

Have you ever played a game of competitive sport when you’re sick? Then you’ll know you simply can’t compete at your best (except if you’re cricketer Dean Jones. Then you’d score 210 while violently ill during a test match in India in 1986 – legend). Crops growing in unhealthy soil can’t compete with weeds. To make matters worse, the unhealthy soil doesn’t seem to affect the weeds as much as it affects the crop. This makes a lot of sense, but there’s been limited research data to support this assumption. Until now. Acid soil is fine if you want to…

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Australian Herbicide Resistance Initiative (AHRI)

Recipe for success

Life Give everything you’ve got Repeat daily Glyphosate resistant awnless barnyard grass High glyphosate rate Small plants Low temperature (if possible) Double knock when it’s hot Annual ryegrass is Australia’s glyphosate resistance champion. The runner up is awnless barnyard grass (in terms of the number of populations). Glyphosate resistance was first confirmed in awnless barnyard grass in 2007 in northern NSW, and it has gone gangbusters ever since. AHRI researcher Heping Han recently teamed up with Michael Widderick (QDAF) to learn a little more about this weed. They discovered that the mechanism for resistance is the Proline 106 mutation. On…

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Australian Herbicide Resistance Initiative (AHRI)

How to beat unfit weeds

How good would it be to turn up to play a game of football or hockey (or whatever your sport) against a team that you know is 30% less fit than your team? It’s a walk up start. As you watch them eat their pre-game pie and smoke their pre-game cigarette, you know that the odds are stacked in your favour.     AHRI researchers recently discovered that some resistant weeds are not very fit. In fact, in this case, the most resistant weeds are the least fit. The 1781 mutation in ryegrass causes moderate clethodim resistance, and high level ‘fop’…

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