Weed management: the broader context - Ecological Management of Agricultural Weeds - page 497

crops, crop rotation, grazing practices, biocontrol agents, cultivation, and
other ecologically based tactics.
In contrast to the highly commercial nature of chemical weed manage-
ment, ecological weed management relies on information that is free or inex-
pensive. Since few companies profit from ecological weed management
methods, they are not advertised in the media and few people are paid specifi-
cally to promote their use.The only public agencies in a good position to even
partially redress this imbalance are extension services. However, extension
educators are often resistant to the concepts of sustainable agriculture and
skeptical about the value of ecologically based approaches to pest manage-
ment (Agunga, 1995; Paulson, 1995; Conner & Kolodinsky, 1997).Training in
sustainable agriculture is now mandatory for extension agents in the USA
(Hoag & Pasour,1992; Schaller,1992).Since training programs vary in content
and effectiveness, however, the impact of this mandate is likely to be spotty.
Both in the USA and elsewhere, additional training of extension agents is still
needed to strengthen the link between ecology and agricultural production.If
ecological weed management is to be implemented on a broad scale, the
public sector needs to place emphasis on improving farmer management of
ecological processes, rather than on programs to promote input use.
Cost externalization
Many costs associated with the production and use of chemical tech-
nologies, including herbicides, are not included in the price of the products.
These include purchase of alternative water sources, cost of medical treat-
ment, lost productivity due to illness and injury, and expenses for clean-up of
pollutants not borne by manufacturers and applicators (Pearce & Tinch, 1998;
see also Chapter 1).Exclusion of these “external”costs from the price of herbi-
cides makes chemical weed management appear more cost-effective than it
actually is for society as a whole. Only when external costs are integrated into
price are they readily visible to all participants in the marketplace (Hawken,
1993, p.83).
External costs are controversial because they can be hard to quantify and
because damage to ecosystems and human health may become apparent only
after a substantial time lag. Nonetheless, failure to estimate and anticipate
external costs can lead to situations where toxic compounds are widely used
for many years, only to be banned after sufficient proof of harm eventually
accumulates. The regulatory history of the herbicide dinoseb illustrates this
situation.It was first registered for use in the USAin 1945.More than 40 years
later, the United States Environmental Protection Agency (USEPA) completed