HERBICIDES in Asian rice - IRRI books - International Rice ...

view, laboratory-produced inoculum was unacceptable for both Devine® and College®
(Bowers 1986). The successful inoculi were produced, however, when appropriate
research was carried out.
Alternative means of production
Much of the discovery and early development of biocontrol agents is carried out and
funded by public institutions, while later development and registration is seen as the
domain of the private sector (Templeton 1990, Marois 1992, Turner et al 1992). Where
commercialization is not likely to occur because of market size or industry perspective,
there may be a role for national and international agencies to undertake further
research and, if appropriate, adopt orphaned mycoherbicides (Templeton 1992). In
particular, this extended role will be needed where analysis of wider social and environmental
costs necessitates alternative weed management tactics within which biological
control could play an integral part. Consistent with this approach, but not the
sole outcome, is the potential for inoculum production on a local scale, at the village
level (Watson 1992a). The mass production of the entomophagous fungus Beauveria
bassiana in Chinese villages, using simple substrates in bamboo trays, illustrates this
approach (Hussey 1990). Contamination problems are overcome by high inoculation
rates. Community or village level production of biological control inoculum has the
obvious advantages of proximity to the end user (obviating the need for long shelf
life) (Auld 1993), low raw material and labor costs, and replacement of imports. It
also avoids the criticism that the desire to relieve the drudgery of hand pulling of
weeds is based more on the interests of powerful commercial forces to penetrate a
market than on concern for labor hardships (Alstrom 1990).
Safety
Bioherbicides may have some limitations in common with agrochemicals. For example,
control of one weed may lead to its replacement by another. However, many of
the problems associated with pesticide use are less relevant when bioherbicides are
used. Increased application resulting in decreased efficacy; greater complexity of pest
problems; nontarget damage; poisoning during production, distribution, and application;
faulty sprayers; nonexistent or poor first aid provisions; and unequal sharing of
benefits and environmental risks among community groups (Soerjani 1988, Forget
1991) are problems of chemical herbicides not shared by biological agents.
Appropriate techniques for applying pesticides are critically important to the safety
of the pesticide applicator (Mohan 1987, Alstrom 1990, Matthews and Bateman 1990).
Chemical herbicides increasingly are being implicated in poisoning cases in less developed
countries, often due to careless attitudes and dangerous practices (Forget
1991). Although it is folly to consider any concentrated substance as completely harmless,
plant pathogens in general have very low or no mammalian toxicity. This means
there is considerably less risk to an inadequately or inappropriately protected operator
who may also have low literacy from a biocontrol agent than from some currently
available chemical herbicides (Alstrom 1990).
Bioherbicides and weed management in Asian ricefields 193