Combating weed issues
NO RAIN as yet and still I know that the dry time will break with a vengeance, possibly more now we are coming into summer.
That means these pesky weeds, no matter what their status, will emerge in droves.
I mentioned last week that we had about six types of herbicide resistance in Australia. There could be more and we just have not located it yet and that is not a cheery thought.
This week I would like to chat about vacuole sequestration, or VS for short.
We all know sequestration simply means placing or in my specific topic for today, secluding or isolating the herbicide away from the normal herbicide target site inside the plant cell.
In this case explaining vacuole sequestration, the herbicide is transported to another location or spot within the plant weed cells, which we can call a vacuole.
They are like little storage bubbles that can store food or specific nutrients, that the cell may need to survive on.
It can also store waste products, or in this case herbicide molecules, and then enzymes can break these waste products/herbicide molecules down to non-harmful products where they remain, until plant death or the leaves fall off.
Is this the mechanism that Paraquat is being sidelined with in Australia now?
Who would ever have thought from the old days, that a desiccant S7 herbicide like paraquat could gain resistant status in plants.
If your particular line of plants are herbicide resistant by the VS means, then I can just see your mind thinking how much applied herbicide can these particular groups of plant survive on, or how much does it take to fill up weed vacuoles in your system.
In other words will a higher herbicide rate assist in controlling my weeds?
Well it probably will do and that is why we should never cut the rate.
There is some research data that supports my paddock-orientated thoughts in not cutting the rates.
However, now there are half a dozen ways of plants developing herbicide resistance in Australia that we know about.
As we know, and are probably sick of hearing about, herbicide resistance is defined as the inherited ability of a biotype to survive and reproduce after being exposed to a herbicide that is normally lethal.
So glyphosate rates at 1L in the 1980s controlling six-inch-sized sow thistle (milk thistle) is now taking 2L/ha is an example of rate creep.
What resistance mechanism is being enacted inside your weed spectrum is unknown just looking from the outside.
Testing of your suspect or blow out paddocks is one option and is much better than flying blind in what mode of action (MoA) is going to work here.
The big action for you to consider is an alternate method of controlling weeds and stopping seed set.
No, I do not just mean go back to round-the-clock cultivating after every weed strike, as we value our moisture and soil too much.
The best ideas come from the paddock and many harvest weed seed operations have started on the family farm. So that is combating
❝No,
I do not just mean go back to round-the-clock cultivating
— Paul McIntosh
weed problems by thinking about alternative solutions.
For my mind, cost effectiveness initially is in using the header to gather and deposit the pin trash/chaff fraction, which includes many of our small weed seeds, in a tramline track behind the header
wheels, so you can deal with them in a narrow row, rather than spreading them all over the paddock.
That way it will not matter what method of resistance they develop and given you keep chipping away at your weed population by this method for some years, that
will bring more successful herbicide applications back into the equation.
You and your agro really need to do brainstorming.
I can see all too clearly that if we rely on herbicides and fancy four- or five-way mixtures and MoA rotation, then our weeds will win.