Diseases and Management of Crops under Protected Cultivation

(Diseases and Management of Crops under Protected Cultivation)
• Less phytotoxic.
Benefits - factors such as increase in yield of the crop that is normally impacted by the
weed. It also include secondary features such as reduction in the usage of chemical herbicides,
which account for 85% of pesticide use in the United States (Templeton 1992).
Fungal and bacterial biocontrol agents are part of natural ecosystem. They are present in
the rhizosphere and can be isolated from any type of soil. All microorganisms produce
metabolites- either beneficial or harmful. Fungal BCAs are specialized and often confused with
fungi producing mycotoxins (Aspergillus, Fusarium etc).
Consumers concern regarding mycotoxins entering the food chain has prompted closer
scrutiny of all the secondary metabolites produced by different biocontrol agents. Biocontrol agents
produce some metabolites in the form of siderophores, enzymes or toxins, to displace/inhibit
competitor. This enables the BCA to compete for nutrients and space. Also for its survival,
metabolites protect BCA against antagonistic microorganisms or mycophagous organisms.
Limitations of Biological control- Biological control is not a panacea and is not risk-free
(Delfosse, 2000). In certain disease management needs and situations where, clearly, another
strategy is more appropriate or should have higher priority. For example, if a new, potentially
invasive pest is found in a localized area, the appropriate strategy is eradication with pesticides.
Biological control is a strategic process with limited use in emergency pest control programs.
Every biological control agent that has ever been used has associated risk. The quantification of
that risk is a very challenging and difficult activity, which has been the subject of extensive
research and discussion.
Risk and biological control- Risk is the probability of the occurrence of a hazard or potentially
harmful effect. It is a relative concept used to imply uncertainty, and estimates and perceptions of
risk change as knowledge improves. Risk can be expressed as the interaction between hazard
and exposure. For risk, the perception is often higher than the reality. Risk is often used when
uncertainty can be quantified to some degree.
An uncertain risk suggests a paradox and a contradiction in cases where the existence of a
hazard has not been established, often a case in Biological control.
Acceptable risk - when uncertainty is quantified to the subjective satisfaction of a viewer.
An irreversible action - limits future options.
Option value arises from retaining an option to a good or service (including, for example, both the
target species and potential nontarget species) for which future demand is uncertain.
Risk analysis- body of knowledge (methodology) that evaluates and derives a probability of an
adverse effect of an agent (chemical, physical, or other), industrial process, technology, or natural
process.
Risk analysis is comprised of risk assessment, risk management and risk communication.
In risk analysis, probabilities of possible outcomes are estimated. Risk analysis should be a
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