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Australian Herbicide Resistance Initiative (AHRI)

Blog: AHRI insight

Grass

Australian Herbicide Resistance Initiative (AHRI)

Focus

Australian golfer Adam Scott keeps his eye on the ball. His ability to concentrate and focus amongst the chaos of a major golf tournament is outstanding. We would all love to focus on one task and do it well, but the reality of life is that we are rarely afforded this luxury. For grain growers, managing resistant weeds is just another thing to fit into the complexity that is farming. Growers that afford themselves the time and motivation to focus on managing resistant weeds are having a win. They declare war on the weed seed bank and have a ‘take…

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Ryegrass growing boxes on tables

Australian Herbicide Resistance Initiative (AHRI)

Rotation plus

Wearing a seat belt reduces the risk of dying in a car accident. The seat belt is not perfect (people wearing seatbelts can still die in car accidents), however it does reduce the risk, particularly when used in combination with other safety technologies (like airbags). In the same way, rotating herbicides is not perfect, but it does reduce the risk of resistance evolving, especially when combined with other weed management tools. We received a lot of feedback and more research data on this issue since the last edition of AHRI insight, and we decided to follow up with a more…

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Ryegrass under vines

Australian Herbicide Resistance Initiative (AHRI)

Double banger – glyphosate and paraquat resistant ryegrass

People who alternate between beer and wine on a night out still end up drunk. Unfortunately, alternating between glyphosate and paraquat could result in resistance to both. Last week in Australian rural media, we heard from Andrew Storrie (Australian Glyphosate Sustainability Working Group) who reported a population of ryegrass that is resistant to both paraquat and glyphosate in a vineyard in Western Australia. Very scary stuff! Is this a freak event that will only happen in vineyards or is it a warning sign for broad acre agriculture? AHRI researcher, Dr Roberto Busi published a paper in 2011 suggesting that perhaps…

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Windrow burning

Australian Herbicide Resistance Initiative (AHRI)

Windrow burning – a good place to start

The best option to maximise the weed seed bank is to harvest high and spread all of the weed seeds evenly over the paddock. This will give you something to spray next year. If you, like most others, feel that this is a bad idea, it may be time to start narrow windrow burning. Narrow windrow burning is a good place to start to see if this harvest weed seed control caper is all it is cracked up to be. The first step is to spend some time familiarising yourself with a beer can. The internationally accepted harvest height when…

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Ryegrass growing boxes on tables

Australian Herbicide Resistance Initiative (AHRI)

Creating a cross resistant monster

Are the wheels falling off the concept of herbicide rotation to manage resistant weeds? In recent years new ryegrass herbicides have been released, giving us some hope that there will be a herbicide solution to our problems. Imagine if your ryegrass was resistant to one of these fantastic new herbicides the first time you used it. We have seen this in the past and we may be about to see it again. AHRI researcher Dr Roberto Busi has previously shown us that low herbicide rates is not good practice as it can lead to faster resistance evolution for some herbicides….

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woman working in lab

Australian Herbicide Resistance Initiative (AHRI)

More resistance = more dormancy

If you drove to work at the same time each day and hit a major traffic jam each time, you might consider changing the time you drive to work. It seems that annual ryegrass has also come to the same conclusion. AHRI research by Mechelle Owen has confirmed that greater seed dormancy is positively correlated with higher levels of herbicide resistance in ryegrass. That is, populations of ryegrass with a higher resistance status had higher levels of seed dormancy, and although these traits are not genetically linked, it does allow ryegrass to germinate later to avoid knockdown (burn down) herbicides….

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Machines plowing field

Australian Herbicide Resistance Initiative (AHRI)

To win the war you must win the battles

As Darkan farmer and inventor of the Harrington Seed Destructor, Ray Harrington, aptly says, “Harvest weed seed control is a pain in the ….” – but it is an imperative tool in continuous cropping systems”. “To win the war you must win the battles. Harvest weed seed control is an important battle. If you’re not implementing weed seed control at harvest, you’re out of the farming game”. It’s a tough message to hear, and it’s one that growers from Wagin, Lake Grace and Ravensthorpe in Western Australia heard at AHRI’s “More crop, less weeds – sustainably!” workshops last week. The…

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Grass

Australian Herbicide Resistance Initiative (AHRI)

Pollen flow of resistance genes

“It wasn’t me, it was him!” Many grain growers blame their neighbours for developing herbicide resistance. Growers often feel helpless! Regardless of how well you manage your weeds, unfortunately it is inevitable that you will inherit the resistance problem from your neighbour. It is true that resistance genes can flow a long way in pollen. AHRI researcher Dr Roberto Busi demonstrated that ryegrass pollen can travel up to three kilometres. More research in theUShas shown that gene flow via pollen varies between species, depending on the level of out crossing and pollen characteristics. It is no surprise that the resistance…

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Weeds sample in glass

Australian Herbicide Resistance Initiative (AHRI)

How do weeds resist glyphosate?

If you ever find yourself in the situation where you are catering for a group of people, and you are wondering how much food to prepare, the best thing to do is to prepare a little extra, just in case. The last thing that you want to do is run out. Believe it or not, this is how some weeds resist glyphosate. They make an extra-large batch of the enzyme that glyphosate binds to, just in case. This way, if the weed is sprayed with glyphosate that inhibits some of the enzyme, there is still enough left for the plant…

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Man touching a plant

Australian Herbicide Resistance Initiative (AHRI)

AHRI Mythbusters – can 2,4-D induce resistance in ryegrass?

What if you accidently sprayed the wrong herbicide? Agronomists of yester-year developed a handy trick. They found that if they accidently sprayed an oat crop with Hoegrass® (diclofop-methyl), they could stop crop damage in its tracks if they quickly applied 2,4-D. The grand question is…does it actually work? The ‘myth’ says yes. What does the science say? The AHRI Mythbusters team got the answer! In this latest AHRI research, Dr Heping Han and others found that when they pre-treated ryegrass with 2,4-D amine it became resistant to Hoegrass®. This is likely due to 2,4-D causing a spike in P450 activity…

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