Managing weeds with insects and pathogens - Ecological Management of Agricultural Weeds - page 401

Despite their potential, herbivory and disease remain largely unexploited
for weed management.Why is this so? How might the situation be improved?
Attention to three sets of issues may improve the development and practical
application of weed biocontrol.
First,an appropriate philosophical perspective is needed.If individual bio-
control agents are expected to act alone with the efficacy and broad target
range of most herbicides, results will often be disappointing. If, on the other
hand, biocontrol agents are viewed as stress factors that are most useful when
integrated with a variety of other weed management tactics, many more
opportunities for success may be encountered. For this to happen, closer inte-
gration of weed biocontrol work with other weed research and extension
efforts is highly desirable.
A second set of issues is technical: weed biocontrol agents need to be pro-
duced in such a manner that they are readily accessible to farmers. Although
many weed-suppressive organisms have been identified, studied, and formu-
lated for application, very few have been brought into the marketplace. The
costs of developing weed biocontrol agents are lower than those for synthetic
herbicides, but commercialization is hindered by small market size due to the
narrow spectrum of control, and the perception of relatively low profits (Auld
& Morin, 1995). Consequently, most companies are reluctant to develop and
register a product that controls only one weed species.
To overcome the inertia of the marketplace, research and oversight by pub-
licly funded institutions are needed to aid individual farmers and coopera-
tives in culturing biocontrol agents for local use.Models for how this might be
done already exist in certain parts of the world. Fermented food products are
made in many homes and small-scale industries in Asia, and the modification
of fermentation technologies to produce weed-suppressive microorganisms is
possible (Mabbayad & Watson, 1995; Auld & Morin, 1995). In Cuba, fungi,
bacteria,and insects are currently produced in small-scale facilities for deploy-
ment in local biocontrol efforts directed toward insect pests and crop patho-
gens (Perfecto, 1994). Similar approaches are needed for producing weed
biocontrol agents in both industrialized and developing countries.
Decentralized programs for producing weed biocontrol agents present chal-
lenges related to quality control, formulation, and storage, but many of those
challenges can probably be overcome. Because of the potential risks to non-
target organisms, national and regional oversight is needed when making
choices about target weed species, herbivores, and phytopathogens in biocon-
trol efforts. But once risks, benefits, and costs are assessed rigorously and
debated thoroughly, local efforts to implement weed biocontrol programs
should be supported.