Cor­rect crop des­ic­ca­tion

Central and North Rural Weekly - - COLUMN - PAUL MCINTOSH

FOR many years now we have adopted farm­ing prac­tices of us­ing her­bi­cides to help in the dry down of our crops, af­ter they have reached phys­i­o­log­i­cal ma­tu­rity.

This her­bi­cide des­ic­ca­tion op­er­a­tion in win­ter and sum­mer crops re­ally does al­low us to get the head­ers into the pad­dock much sooner, rather than just al­low­ing nat­u­ral plant dry­down.

Of course the chal­lenge is al­ways the judge­ment of as­sess­ing the over 90 per cent phys­i­o­log­i­cal ma­tu­rity mark in our an­nual crops, which is the rough fig­ure most agros use when scout­ing pad­docks for des­ic­ca­tion tim­ing. Phys­i­o­log­i­cal ma­tu­rity has terms such as black point or black layer, which in­di­cate in ce­real grain, the seed has stopped fill­ing and is sep­a­rated from the mother plant. So log­i­cally, no ex­ter­nal fac­tors in that crop such as more ir­ri­ga­tion/rain events or even en­vi­ron­men­tal fac­tors such as frost could af­fect the size or fill con­tent of this grain. In legumes such as soy­beans and mung­beans this phys­i­o­log­i­cal ma­tu­rity tim­ing is when the seeds in the pod have sep­a­rated from the white mem­brane lin­ing the plant pods.

So our best prac­tice of crop des­ic­ca­tion is a nec­es­sary part of our farm­ing sys­tem for dry­ing down our crops to en­able the har­vest to oc­cur, as soon as the header can op­er­ate and the grain sam­ple is good.

The drier all the plants are, in­clud­ing the weeds in the pad­dock, the quicker and more ef­fec­tive is the har­vest op­er­a­tion.

So hav­ing out­lined the many of the ben­e­fits in des­ic­ca­tion that we have been us­ing for over 30 years in some crops, what can go wrong in the fu­ture?

Some shock news last week was the in­ten­tion of Eu­rope to ban the ac­tive in­gre­di­ent di­quat (orig­i­nally known as re­glone) and all as­so­ci­ated prod­ucts in the EU. So un­less ne­go­ti­a­tions by our grain ex­port lead­ers in the Eu­ro­pean re­gion are suc­cess­ful, by early 2020 this long-term des­ic­ca­tion prod­uct will no longer be able to be used in Aus­tralia for ex­port pulse or oilseed crops to the EU.

Then a cou­ple of weeks ago, there was ma­jor me­dia ex­po­sure on our very use­ful farm­ing prod­uct in glyphosate. The pres­sure is com­ing from ev­ery­where, isn’t it, on our pes­ti­cide us­age pat­terns?

What all this high­lights in the year of 2018 is that our ab­so­lute crit­i­cal her­bi­cide weed con­trol meth­ods, which we have de­vel­oped and used over many years, are get­ting stran­gled by forces out­side our con­trol.

These out­side forces high­light a few things or warn­ings to me.

We all need to ad­here strongly to the la­bels or the per­mit­ted use on all pes­ti­cide prod­ucts.

We know from bleak ex­pe­ri­ence the EU takes ex­cep­tion to hav­ing the grass killing ac­tive in­gre­di­ent of haloxy­fop MRLs ex­ceeded in ex­ported pulse crops to them. I believe some EU coun­tries refuse to have our favourite fop her­bi­cide at all on im­ported pro­duce. This one ex­am­ple sure gives me the en­thu­si­asm to ex­plain at ev­ery field day I at­tend, to not ap­ply this handy grass con­trol agent of haloxy­fop on to flow­er­ing pulse crops. Many la­bels are con­fus­ing on tim­ing and some place­ment of word­ing is tricky to un­der­stand, when just glanc­ing at the small print that la­bels of­ten carry, so read care­fully.

The sec­ond thing is our her­bi­cide re­sis­tance lev­els are in­creas­ing and with large rain­fall events be­ing re­ceived by some of us , the amount of weed growth is enor­mous. So we have large num­bers of weeds grow­ing with her­bi­cide re­sis­tance spread­ing rapidly. Many of us are go­ing to be tempted to use larger rates of her­bi­cide both in fal­low and in-crop.

We are re­ally push­ing the bound­aries and with so much so­phis­ti­cated grain test­ing equip­ment these days, it could end in tears and be very costly for the grain pro­ducer.

So once again, I chal­lenge us all to find and prac­tise al­ter­na­tive cul­tural meth­ods of weed con­trol. It is a num­bers game as usual with weed seeds, just like the heloithis re­sis­tance prob­lems we had in the late ‘80s and ‘90s. Stop the weed seed set by other means, other than the her­bi­cide band­wagon with a diver­sity of op­tions.

We need our her­bi­cides to last for many years yet, so an­tag­o­nis­ing our over­seas mar­kets and in­creas­ing the her­bi­cide re­sis­tance lev­els on our own farms does not make sense to me.

My own life­time of ex­pe­ri­ence with pes­ti­cides use has been pos­i­tive and I want that to con­tinue along this path­way, how­ever we need to be prag­ma­tists and look at other op­tions for pest con­trol, es­pe­cially our weeds.


PESKY WEEDS: Fence­lines can be­come nurs­eries to weed seeds.

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