Diver­sify meth­ods of at­tack

Try more weed-con­trol tac­tics

Central and North Rural Weekly - - COLUMN - PAUL MCIN­TOSH

❝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-en­ergy-guz­zling mi­crowave tech­nol­ogy down to ba­sic plas­tic mulching.

One very in­ter­est­ing lot of re­search pre­sented to a re­cent weed re­search meet­ing was on a bi­o­log­i­cal weed-con­trol 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 milk this­tle (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.

START­ING TO SPROUT: Weeds are aplenty in pad­docks on the Dar­ling Downs af­ter solid rain­fall last month. PHOTO: CON­TRIB­UTED

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