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Australian Herbicide Resistance Initiative (AHRI)

Blog: AHRI insight

Gregor Mendel

Australian Herbicide Resistance Initiative (AHRI)

When on a good thing…

My mother has brown eyes and my father and I have green eyes. How does that work? Answer, Mum was a heterozygote. No this is not some deadly disease, it simply means that on one chromosome she has the dominant gene for brown eyes, and on the other she has the recessive green / blue eye gene. Mendelian genetics explains how plants and animals inherit traits from their parents and has been used by AHRI researcher Dr. Roberto Busi to show why it is a good idea to rotate herbicides. This study showed that Sakura® (pyroxasulfone, Zidua® in U.S.A) resistance…

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Piece of grass

Australian Herbicide Resistance Initiative (AHRI)

Just add water

It regulates Earth’s temperature, our bodies need it when we’re thirsty, and it covers about 70% of Earth’s surface. Water is essential for a number of reasons, and here is one more. Most Australian growers and agronomists would expect that 2.5 L/ha trifluralin or the full label rate of Sakura® would give between 70 and 90% ryegrass control in crop. However, research by Dr Catherine Borger (DAFWA Merredin, WA) has shown that it depends on how you apply it. Catherine found that ryegrass control with Trifluralin or Sakura® increased from 53% to 78% as the carrier volume increased from 30…

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Brome grass

Australian Herbicide Resistance Initiative (AHRI)

Perfect storm

A perfect storm is brewing for what could potentially be another big herbicide resistance problem in Australia. The Group B herbicide sulfosulfuron (Monza®) is about to get a lot cheaper, and many growers are looking to increase their use of Group B Imi tolerant barley and wheat varieties in the near future. Past experience tells us that reducing the price often results in dramatic increases in the use of a given herbicide. This is likely to have a big impact on the evolution of Group B resistance in brome grass and barley grass. AHRI researcher Mechelle Owen found that 13%…

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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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