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OPINION: More tools for the herbicide resistance toolbox

TOUGH JOB: Double and triple knock-downs are becoming more common across the country.
TOUGH JOB: Double and triple knock-downs are becoming more common across the country.

STILL on weed control solutions, apart from applying increasingly heavy mixes of herbicide or the unpopular thought of back to constant primary and secondary tillage operations.

Many of you are committed for a variety of positive reasons to zero or even strategic minimum till.

The benefits of this herbicide farming system have been obvious since we all started on this zero till phenomenon in the early 1980s and it is only the increasing threat of herbicide resistance that is making us consider changing tactics.

I heard a highly experienced agro friend of mine describe a major production constraint as "the tidal wave of herbicide resistance” bearing down on all of us.

We have been double knocking and triple knocking for some years now, along with utilisation of residual herbicide programs and if we get a blow out, you reluctantly get out the cultivator in the middle of our heavy summer storm period.

We really need to think about controlling the weed seed bank by other methods. I have been saying this for some time now about using our best collection device, namely the header, and positioning weed seeds in one spot in the paddock where you can deal with them.

My first thought some time ago was that it would not work, because all the weed seeds will have dropped on the ground prior to harvest or the weed seed will be below header height.

Well, after looking at the research data and even looking back over hundreds of paddocks I have personally walked over the past 40 years, this is not always true.

Besides I could always come up with a super herbicide mixture that will clean up weeds either in fallow or in crop.

No trouble at all and I had plenty of practice at these three or four and even five way mixes over the years.

Roll on to 2017 and increasingly I have phone calls from farmers mostly, that they need to consider alternate weed control options.

So the conversation starts about weed species and seed produced numbers, controlled traffic, harvest weed seed techniques, cost of implementation, time taken to achieve success and myriad other questions.

No, I do not have the answer to them all, however many of you innovators out there will have some blue sky thoughts on weed control in the future for our northern country.

Last week I spoke about chaff lining, which deposits the chaff fraction only into a single line behind the rear of the header between the wheel tracks.

A low-cost and easy to install method that collects weed seed in the chaff fraction (pintrash to some of us) and places it in a narrow row, instead of spreading it all over the paddock for the next rainfall event.

A slight deviation to chaff lining is the chaff deck or chaff tramlining, which uses the same principle of using the header front as the collection device and dropping this same chaff fraction including weed seeds, onto your controlled traffic lines or tramlines .

These tramlines or permanent wheeltracks present a hostile environment for weed seed to germinate or remain viable due to rotting etc, as observed by many southern and western farmers and agros.

It was even noticed that dust from wheels in future spraying operations was much reduced, which is a huge benefit in our summer spray regime.

That is why you should consider a trip south to Wagga for Weedsmart week in late August with me to listen and see farmers set up and practising various harvest weed seed control methods.

Herbicides have been a great option to us all over the years, however if we want them to continue being useful and retain their use pattern, then using alternate weed control methods by reducing the weed seed bank numbers is part of the future.

Topics:  herbicide resistance paul mcintosh


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