Need Safeguards for Gene-Tinkered Foods

C.K. Black CBlack at massey.ac.nz
Sun Jun 27 22:29:43 EST 1993


 In Message-ID: <C97AKG.z6 at dartvax.dartmouth.edu>, Jim Wellehan writes...

>In article <SANDY.93Jun25110244 at nmr1.pt.cyanamid.COM>
>sandy at nmr1.pt.cyanamid.COM (Sandy Silverman) writes:

>>         One reason for engineering herbicide resistant crops is that you
>> may be able to use a less toxic or lower use rate alternative and get the
>> same protection with a better environmental impact.

>Could you please explain this?  It seems to me that if you wanted to be
>able to use a less toxic or lower use rate alternative, you would have
>to engineer herbicide-susceptible weeds :-).  I fail to see how
>resistant crops are good for anything but allowing higher levels of
>herbicide to be used.

I'd be glad to explain it to you Jim.  Think of it this way,  the farmer
is limited in his choice of herbicides in that he must select one which
controls particular weeds in his fields but is safe for the crop which he
plans to grow.  The herbicide must also be applied at rates which are 
sufficient for control of the target weed species.
  In the 'corn belt' of the US, they use a lot of triazine type herbicides,
(atrazine, simazine etc.) at rates of 1000 - 2000 gms. a.i./ha.  It can 
cause problems with residual herbicide affecting the growth of the next
years crop if it is something other than corn & soybeans.  After years of
use it might also get into the water table.  If we had corn that was
resistant to say, chlorsulfuron,  which is applied at 10 - 20 gms a.i./ha,
then we would have a "lower use rate alternative".  If we had corn that
was resistant to glyphosate, then we would have a "less toxic alternative".
  Along the same lines, if we CAN'T get those specific resistance genes
into corn,  maybe we can get them into another crop specie and thus allow
the farmer to have a broader choice in his crop rotations.  I understand
that triazine resistant canola fits this category (but I'm not sure if it
was 'gene-tinkered',  Larry at U of Guelph might be able to help).
  I can't see the 'gene-tinkering' of herbicide resistance into crops
increasing the total use of herbicides,  the economic margins just are not
there for the farmer.  What it will do for the chemical companies is to
broaden the potential use of their specific product.  Hence, they might be
able to increase their 'market share' relative to their competitors.
Cheers......
-- 
Conrad Black 

Email... C.K.Black at massey.ac.nz
Snail... Massey U., Plant Sc. Dept., Palmerston North, New Zealand



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