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Australian Herbicide Resistance Initiative (AHRI)

How do weeds resist glyphosate?

Tag Archives | evolution

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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Wild radish flower

Australian Herbicide Resistance Initiative (AHRI)

Is there a fitness penalty in Group B resistant weeds?

When we talk about the fitness of weeds, it’s not about how fast they can run a marathon. We are talking about how well they grow and how many viable seeds they produce. Weeds with fitness penalties just don’t grow and reproduce as well as they should, even in the absence of herbicides. Are there fitness penalties for Group B (e.g. Glean®; ALS inhibitor) resistant wild radish? Visiting researcher, Mei Li, along with other AHRI researchers, set out to answer this question. Unfortunately, the answer is NO! Wild radish, with four different target-site ALS mutations, were equally as fit as…

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Plants in flowerpots

Australian Herbicide Resistance Initiative (AHRI)

The rate debate

Many a late night has been spent over a glass of red at weeds conferences around the world debating whether high or low herbicide rates lead to faster resistance evolution. All weed scientists have an opinion on this issue, some of which are held very tightly. To some extent, the debate is still raging because the answer is not straight forward. The answer is both. As you can imagine, both sides of the debate are claiming victory! What we do know is that low herbicide rates have been documented to lead to rapid resistance evolution to Hoegrass®, Roundup® and Sakura®…

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Nature landscape of grass trees and sky

Australian Herbicide Resistance Initiative (AHRI)

Think outside the drum

If herbicides alone were the answer to all of our weed problems we would have eradicated crop weeds years ago. Most of us now realise that to achieve true weed control success we need to add non-herbicide tools into the mix. It doesn’t matter which weed, which crop, or which country we are talking about, the benefits of good cultural practices apply everywhere. Some excellent long term Canadian research has confirmed how important it is to combine good cultural practices with herbicide use. The Agri-Food Canada trials show that after nine years of full herbicide rate, high barley seeding rate,…

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Wild Oat

Australian Herbicide Resistance Initiative (AHRI)

Why do Wild Oats evolve resistance slowly?

Why is it that we can often kill wild oats (black oats) with grass sprays but the ryegrass in the same paddock evolved resistance to these herbicides years ago? The answer is in the genes. Ryegrass is like we humans – it must cross pollinate to reproduce and it has two copies of each gene (diploid). Wild oat is more like wheat – it mostly self-pollinates (88 to 100% self-pollination) and it has six copies of every gene (hexaploid). A single gene mutation can cause ryegrass to be resistant to a grass herbicide but it will have only a minor…

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