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Appendix Two: The Indirect Benefits of Genetic Engineering are Not Sustainable
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Appendix Two
The Indirect Benefits of Genetic Engineering are Not
Sustainable
THE use of genetic engineering to improve
weed control could have a significant
impact on crop yields. Weeds are an
important problem in agriculture. The
annual cost of weeds has been estimated at
US$20 billion in the US (reported in Basu
et al., 2004) and ~A$4 billion in Australia
(Sinden et al., 2004). Generally, these costs
are incurred by both loss of crop because
of the direct influence of weeds and the cost
of weed control. In Korea, 5-10% of rice
yield is lost to weedy rice (Chen et al.,
2004). “Volunteer wheat and barley, at 7 to
8 plants/m 2 (6 to 7/yd 2 ) can reduce canola
yield by 10 to 13%” (Canola Council,
2007). The DuPont company estimates that
without some form of weed control, “the
average crop losses for U.S. corn, soybean
and cotton growers would be approximately
65%, 74% and 94%, respectively” (DuPont,
2008). There can also be environmental
benefits of weed control, but these are
poorly quantified (Sinden and Griffith,
2007).
The Assessment text
Synthesis Report (p. 44)
Regardless of how new varieties of crop
plants are created, care needs to be taken
when they are released because through
gene flow they can become invasive or
problem weeds, or the genes behind their
desired agronomic traits may introgress
into wild plants threatening local
biodiversity. Gene flow may assist wild
relatives and other crops to become more
tolerant to a range of environmental
conditions and thus further threaten
sustainable production. It is important to
recognize that both biodiversity and crop
diversity are important for sustainable
agriculture. Gene flow is particularly
relevant to transgenes both because they
have tended thus far to be single genes
or a few tightly linked genes in genomes,
which means that they can be transmitted
like any other simple trait through
breeding (unlike some quantitative traits
that require combinations of
chromosomes to be inherited
simultaneously), and because in the
future some of the traits of most
relevance to meeting development and
sustainability goals are based on genes
that adapt plants to new environments
(e.g., drought and salt tolerance).
(From Agriculture at a Crossroads: The
Synthesis Report by IAASTD, ed.
Copyright © 2009 IAASTD. Reproduced
by permission of Island Press,
Washington, D.C.)