Diversify methods of attack
Try more weed-control tactics
❝The definition of a weed is a plant out of place by my reckoning. — Paul McIntosh
THE definition of a weed is a plant out of place by my reckoning, and for many of us the recent rain events have brought up thousands of these out-of-place plants.
These true weeds, as we can call them, which farmers do not make any money out of, deplete the soil of precious moisture and nutrients.
This group of unwanted plants seems to occupy a lot of resources in time and money in getting them under control so we can then grow our profitable and desirable crops.
We all accept the increasing spectre of herbicide resistance is gaining a bigger foothold in our farming landscape every day. We also know that agronomists and farmers for years have been using some extreme herbicide multiple-way mixtures to try to gain a complete kill in every paddock of these weedy jungles.
So how long will our raft of herbicides last if we continue doing this mass-mixing procedure? Good question. However I will suggest our better paddocks or our most utilised paddocks are going to suffer the most, as we juggle herbicides both knockdown and residual types with cropping frequencies and species choice.
Those who read this column will recall many occasions where I have urged you to take the challenge and look at different cultural methods of weed control .
So what are some of the ‘way out’ means of weed control that many are talking about but science has not caught up to as yet?
I work in with some very smart people in many facets of agriculture and none more so than in weed-control science groups like the Australian Herbicide Resistance Initiative unit.
Another major research group, mostly funded by GRDC, is based at Narrabri. This group, led by Michael Walsh, is looking at various ways of targeted tillage, where one option is having retractable tynes mounted on a cultivator machine, imitating the action of a chipping hoe on weeds. These weeds are detected by green-seeking cameras and initiate the downward motion of the tyne as the tractor and cultivator move past. That is fast coming to commercial realisation, however the team is not stopping there with this method.
Other weed-control options are being investigated across the country and some we have heard about and some are very fanciful still.
Things to aid weed control range from microwaves, hot air, freezing, steam, hot foam, hot water, infared, flaming, UV and so on, into our various mechanical options. All these wild ideas are being evaluated somewhere. However, as Michael has calculated, they all take energy to run, starting from the very high-energyguzzling microwave technology down to basic plastic mulching.
One very interesting lot of research presented to a recent weed research meeting was on a biological weedcontrol agent. As Queenslanders we all know the story of the cane toads being imported to chase out the sugar cane grub and how bad that ended up, however we also know the success of the cactoblastis on prickly pear.
Other targeted weed-control methods involve highpressure water jet cutting, stamping, lasers and electrocution. So who would want to be a weed when these diverse control methods are being developed. One thing none of us should expect is another silver bullet like glyphosate to be discovered.
It was discarded by the original chemical company as it did not do what it should have done in an industrial situation when the molecule was first discovered. No one in that company in the early 1960s tested it for weed control.
So while we have some amazing technology developing in weed control, we all still need to accept the challenge of keeping weed seed numbers down on our farms and roadsides.
I had a researcher advise me the other day the humble milkthistle (or common sowthistle) in just one well-grown adult plant yielded up to 200,000 seeds, which could have been released into the wind and surrounding area. Just one plant going to seed, and then add in the increasing rate this species is becoming more resistant to various herbicide modes of action, including glyphosate, and it’s quite scary.
So I suggest you maintain or increase your successful weed-control capacity by diversifying your control tactics. Did you know that if you control successfully any annual plant before it sets seed, you will never develop herbicide resistance on your property.